Saturday, May 21, 2011

Top 10 Signs of Hyperthyroidism in Cats

Hyperthyroidism is one of the most common endocrine conditions affecting cats, especially older cats over the age of 10 years. Some veterinarians estimate that about 5 to 10% of middle- to old-aged cats will develop hyperthyroidism, and, due to factors that may include environmental exposures, that number is on the rise.

Thyroid hormones normally regulate many of the body’s metabolic processes. As circulating levels of thyroid hormones rise higher and higher in cats with hyperthyroidism, a progressive increase in their metabolic rate develops: this leads to a multitude of changes throughout the entire body, including loss of weight and muscle wasting. High thyroid hormone concentrations also interact with and stimulate the central nervous system, which commonly leads to increased activity or restlessness, as well as other behavior problems.

Clinical signs associated with hyperthyroidism can be quite dramatic and cats can become seriously ill with this condition. Untreated, hyperthyroidism in cats can lead to heart or kidney failure and can be fatal.

However, this disorder is a very treatable disease and most hyperthyroid cats will make a complete recovery. I’d discuss the various treatment options, together with pros and cons of each form of treatment, later in this current series of posts I’m doing on feline hyperthyroidism.

Do You Know the Clinical Signs of Hyperthyroidism to Watch for in Your Cat?
Here I’ve listed the top 10 most common signs that cats with hyperthyroidism can develop, from most common to least frequent.

Your cat doesn’t need to have all of these clinical signs or symptoms in order to have an overactive thyroid problem. But if your cat has one or more of these signs, especially if he or she is older than 10 years of age, you should definitely have your cat tested for hyperthyroidism.

1. Weight loss
Weight loss despite a normal to increased appetite is the classic and most common sign of hyperthyroidism in cats. Hyperthyroidism is so common that it should always be considered as a possibility in any middle-aged to older cats that has lost weight, even in none of the other clinical features of the disease are present.

The weight loss associated is generally progressive and is usually first noticed by the owner as a loss of muscle mass around the cat’s back (spine).

With time, severe muscle wasting, emaciation, and death from starvation can occur if the cat’s hyperthyroidism is left untreated.

2. Increased appetite
The weight loss characteristic of cats with hyperthyroidism is typically associated with an increase in the cat’s appetite. This increase in appetite can be dramatic, with some cats doubling the amount of food eaten and frequently begging for food. Hyperthyroid cats eat more in an attempt to compensate for their higher-than-normal metabolic rate by increasing the number of calories ingested. Unfortunately, most cats cannot fully compensate and continue to loss weight even if they have a good to increased appetite.

Although most hyperthyroid cats have an increased appetite, some cats with mild hyperthyroidism will maintain a normal appetite, with no obvious change in amount of food consumed.

A few hyperthyroid cats will even develop a reduced appetite that is improved after treatment of their hyperthyroidism. Most of these cats with a poor appetite have a rare form of hyperthyroidism called “apathetic hyperthyroidism,” which is described in more detail below (see clinical sign Number 10).

3. Hyperactive, increased energy, or nervous behavior
Hyperactivity, exhibited particularly as nervousness or restlessness, is relatively common in cats with hyperthyroidism. In extreme hyperthyroidism, muscle tremor or twitching may be apparent, and affected cats are often described as having an anxious or frantic facial expression.

In some cats, especially in the earlier stages of their hyperthyroidism, their owner can misconstrue such increased activity and energy as a positive sign of health. One must remember that cats normally become quite sedentary as they age so this change of behavior leading to increased energy and activity is almost always a manifestation of an underlying disease processes.

Some of these behavior signs — especially restlessness or aggression — are often more noticeable to the examining veterinarian than to the cat owners themselves. Many hyperthyroid cats have an impaired tolerance for stress and do not wish to be held or restrained. Some will even develop a “panic attack” as a result of an impaired tolerance for examination or restraint during blood sampling. These cats may also develop panting, overt respiratory distress, weakness, and even collapse during these episodes.

To see a video of severe anxiety in a cat with severe untreated hyperthyroidism, see my previous blog post.

4. Increased thirst and urination
About half of cats with hyperthyroidism will show signs of increased thirst (polydipsia) and urination (polyuria). Veterinarians often refer to polyuria and polydipsia simply as “PU/PD.”

There are a number of possible reasons for the increase in thirst and urination seen in hyperthyroid cats. The most common explanation for the PU/PD is mild, concurrent kidney disease. About a third of all cats older than 12 years of age will develop kidney disease, so the finding of concomitant kidney disease in a hyperthyroid cat should not be surprising.

Two other causes for polyuria and polydipsia in cats with hyperthyroidism include the following:
  1. Increased kidney blood flow occurs secondary to hyperthyroidism, which can lead to what’s called “renal medullary washout.” This leads to the inability of the cat to concentration their urine normally.
  2. Compulsive water drinking secondary to a behavior problem may also occur in some cats with hyperthyroidism.
In both groups of these cats, the increased thirst and urination return to normal after treatment of the cat’s hyperthyroidism.

5. Vomiting or regurgitation
Gastrointestinal signs including intermittent vomiting or regurgitation are fairly common in cats with hyperthyroidism. Vomiting may result from a direct action of thyroid hormones on an area of the brain called the chemoreceptor trigger zone. In other cats, the vomiting can result from gastric stasis (e.g., delay emptying of the stomach).

Vomiting appears to be more common in cats from multi-cat households and usually occurs shortly after feeding. Therefore, vomiting and regurgitation in most hyperthyroid cats may simply be related to rapid overeating. In other words, these cats eats too much food too fast, overfill their stomach, and then vomit.

One solution to this problem during the early stages of treatment is too feed the cat smaller amounts of food more frequently (every 3 to 4 hours, if possible).

6. Anxiety, night yowling, confusion, aimless pacing
The behavioral sign most obvious to owners is night yowling (a long loud mournful cry). This yowling most often occurs in the middle of the night for no apparent reason, and generally causes the owner to awaken. Aimless pacing and easily interrupted sleep patterns may also occur in some hyperthyroid cats.

All of these behavior signs appear to reflect a state of confusion, anxiety, or restless associated with the increased central nervous stimulation caused by the hyperthyroidism.

7. Diarrhea, soft stools, voluminous stools
Soft stools and diarrhea can occur in about a third of cats with hyperthyroidism. Other cats develop large voluminous stools with frequent defecation.

It is likely that accelerated gastrointestinal transit contributes to the increased frequency of defecation, soft stools and diarrhea. Some of these cats also develop malabsorption, in which they do not normally absorb the food from the intestinal tract.

8. Fast respiratory rate, panting, difficulty breathing
Respiratory abnormalities, including a rapid respiratory rate, panting, or difficulty in breathing at rest, are also common. Respiratory signs tend to occur most frequently during periods of stress. However, some affected cats will be noticeably intolerant of heat and seek out cooler places to sit, and some (especially advanced cases) may pant or breath more rapidly in warm or hot home environments.

In the absence of heart failure, weakness of the respiratory muscles due to chronic hyperthyroidism is the most probable reasons for these signs. However, central nervous or psychogenic effects also play a major role in development of these respiratory signs, especially in states of stress.

When severely stressed, some cats with hyperthyroidism will develop severe respiratory distress, rapid breathing, and panting; in addition, these cats may eventually become extreme weak or even collapse from exhaustion and shortness of breath. Hyperthyroid cats should therefore be handled carefully and in the veterinary office.

9. Skin, hair coat, and nail changes
Unkempt, matted hair coat
Skin and hair coat changes often develop in hyperthyroid cats. The hair coat, especially in long-haired breeds, is often unkempt, dull, and may even be matted.

Some hyperthyroid cats can groom obsessively resulting in alopecia (baldness) or a miliary dermatitis (crusty rash, often with intense itching).  This is sometimes associated with an underlying skin allergy, but the skin problem is magnified by the cat’s apparent obsessive and compulsive behavior associated with increased licking and grooming.

Excessive nail growth may also occur, especially in cats with chronic and advanced hyperthyroidism. These nails appear thickened and may be more fragile that normal.

10. Apathetic hyperthyroidism
A small percentage (less than 5%) of hyperthyroid cats will show atypical signs where hyperexcitability or restlessness is replaced by depression, apathy, or weakness. Although weight loss is present in these cats, it is accompanied by poor appetite, instead of increased appetite. These disparate signs heighten the importance of clinicians having a high index of suspicion for such a common disease.

Many cats with apathetic hyperthyroidism will have concurrent severe non-thyroidal illness such as kidney failure, heart disease, or cancer. Therefore, it is wise to do a complete workup in these cats searching for secondary or concomitant disorders. Occasionally, however, no other medical problem can be identified and the cats respond completely to treatment of hyperthyroidism alone, with resolution of the depression and poor appetite.

In my next blog post on hyperthyroid, I’ll describe the 12 most common findings that your veterinarian may find when they perform a physical examination on a hyperthyroid cat.


Anonymous said...

OMG, my cat of 6 and half years has almost all of the Top 10 signs of hyperthyroidism, I wasn't sure until I read this blog now I'm almost certain he has this condition

Thanks for posting this info.

Sarah Eargle said...

Could a cat with this disease do the opposite of losing weight and instead gain. Several of these items fit my cat only his appetite has increased and he has gained almost 7lbs since May. The vet said he had worms and treated him 1 month ago since then he has gained 2 more lbs. Please help he is over 10 an old tom. I do not know what to do.

Dr. Mark E. Peterson said...

It's highly unlikely that hyperthyroidism could lead to a marked weight gain that your gain is showing.

However, since your cat is over 10 years of age, running a serum T4 test to rule out hyperthyroidism is not a bad idea. If it's normal, then you have ruled out this problem.

Melissa said...

My 15 year old cat has just been diagnosed with hyperthyroidism. She has lost a lot of weight and started breathing deeply. She has only been treated for 5 days so far. Should her breathing return to normal once she puts on some weight or is she doomed?

Melissa said...

My cat was recently diagnosed with hyperthyroidism. She has lost a lot of weight and started breathing deeply. The vet said her breathing deeply is due to the weight loss. She's been treated for 5 days so far, once her thyroid is regulated and she gains weight, should she start to breath normal or is she doomed?

Dr. Mark E. Peterson said...

Many cats with hyperthyroidism have an increased respiratory rate that normalizes within a few days to weeks, once the serum thyroid hormone concentrations return to normal.

However, some cats with hyperthyroidism will develop heart failure, so you might want to have a chest x-ray done if the trouble breathing continues. Even if that is the case, medication can be given to help support heart function so I don't think your cat is doomed!

Good luck!

AnimalsRule said...

Dr. Peterson, my best friend has a cat who is 19 years old, eating quite a lot of food, but seems to have lost control of his bowels as well. He will defecate while he is sitting or lying down and sleep in it. He has lost interest in cleaning himself. Is there any chance it could be Hyperthyroidism or is this more a normal occurrence with old age? He does not want his little buddy to suffer, but if there is a chance to save him where he is not in pain, that would obviously be his desire. Any thoughts you have would be greatly appreciated.

Enid said...

Our 19-year-old cat has hyperthyroidism and has been on medication for the past 3 1/2 years. Over the last year, we have noticed that he is dropping stools outside of his litter box. I was wondering if there is some sort of dementia occurring. It has been suggested to us by our vet that there is an association with constipation, but when given a stool softener, our cat's behaviour didn't change.

Dr. Mark E. Peterson said...


Yes, older cats can develop a form of senility. Talk to your vet about that and see if treatment is recommended.

Dr. Mark E. Peterson said...

To "AnimalRule"

It certainly sounds like your cat could be hyperthyroid. I'd recommend that you check a serum T4 level which will make the diagnosis (or rule it out). The test is very simple to do.

Michelle R said...

Dr. Peterson - Our 13 y/o cat was diagnosed HyperT and has been on Tapazole for 3 months. He began losing hair before diagnosis and has continued to lose/lick/bite off 2/3 of his hair. Even though his T3/T4 levels are normal, he still seems anxious and is licking his body raw. All biopsy/dermatology/bloodwork has come back negative for cancer, bacterial, parasitic or fungal infection. We are at a loss. Could this behavior be HyperT or Tapazole related? We are hoping I-131 will cheange his demeanor/self-mutilation. What are the chances?

Dr. Mark E. Peterson said...

We do see cats with untreated hyperthyroidism develop excessive licking and hair loss. And we also see excessive pruititis (itching), especially around the face, after methimazole in some cats.

What bothers me about your cat is that the problem was present before the methimazole was started and now it has continued despite control of the high T4 value. That really suggests that something else is causing the skin problems.

Have you seen a veterinary dermatologist? A specialist may be needed to help exclude or diagnosis other problems causing your cat to lose hair and lick his body so much.

Renee Michelle said...

Could it be anxiety or pain? He started showing symptoms after a trauma 1 year ago (dog attack, the dog lost). His pupils dialate often and he seeks heat and body contact a lot. Seems depressed, though he has energy and appetite. Yes, we saw a dermatologist - he is negative for surface fungus and bacteria and they did a complete senior blood workup that came back excellent. He had a biopsy of a skin lesion and lymph node (which are enlarged) - the initial test was for cancer and it came back negative, just reactive lymph. We resent the sample for special staining looking for bacterial/fungal infection (negative). He is on his 6th day out of 14 on doxycycline just in case something was missed - so far no improvement, so we started him on prednisolone yesterday because he is miserable. So miserable that he peed on the bedroom rug, first time ever. He is on grain-free food, we ruled out food allergies via elimination diets. I mean - what in the world? The only thing that has not been done is stool/urinalysis, homeopathy, accupuncture or a visit with an endocrinologist (that's where you come in). Bless you for your response. Your blog has been a real comfort and education!

Dr. Mark E. Peterson said...

Your cat's problems certainly could be psychological and related to anxiety. Have you considered seeing a behaviorist? They might be able to offer some suggestions.

Good luck with him - sorry I don't have the answer but this is a tough one to figure out. You certainly have done your best trying to get the answers.

Renee Michelle said...

Thank you. Help me to understand something - how symptomatic can a HyperT cat present when euthyroid while on Methimazole? Or rather how endocrinely sick can a cat be while euthyroid due to Methimazole? I'm wondering if my cat's over-all hormonal balance will improve even more if we go ahead with I-131. I need to know if I will be doing his health more good than harm. There is much we don't understand with this cat - however his blood work and tests are pristine with the exception of high WBC (which I understand is typical for his condition). Thanks so much.

Dr. Mark E. Peterson said...

Some cats will have a normal total T4 level on methimazole but still be hyperthyroid. That is especially true if a cat has a total T4 over 3 μg/dl or has concurrent nonthyroidal illness.

To check that possibility, we would measure a complete thyroid panel, which includes at least a free T4 by dialysis and TSH level, in addition to a total T4 concentration.

Bruce Campbell said...

Hello Dr. Peterson, I was wondering if stress can increase the T4 levels in a cat. The vet has to sedate my cat for every visit to perform any examination and to take blood work. My cat's T4 levels have gone up since she has been on medication. She was on a low dose and then went for a recheck for blood and of course she had to be sedated again. After the second blood test her levels were even higher. She doesn't show any visible signs of hyperthyroidism except for the T4 levels.

Dr. Mark E. Peterson said...

No, stress or sedation should not increase the levels of T4 in a cat. If anything, stress (especially secondary to other illness) would "falsely" lower the T4 level.

Many cats, especially those who are relatively young (< 13 years) or those suffering from early/mild disease, will not show overt signs of hyperthyroidism.

K Medcalf said...

Hi Dr Peterson. Can you tell me if a cat can have hypothyroidism and then hyperthyroidism? I have a 14 year old cat who from the age of 5-12 ish was very lazy,sleepy and fat (I asked my vet at the time if he was hypothyroid but he dismissed this). He picked up over the past few years but in the past 3-4 months he has become very thin and his appetite has increased and I am about to take him to our vet to discuss whether he now has hyperthyroidism, have you seen this happen in cats?

Dr. Mark E. Peterson said...

Spontaneous hypothyroidism is a rare disease in cats and I really doubt if your cat was ever hypothyroid. However, if he was hypothyroid, it is not really possible for him to then develop a thyroid tumor and become hyperthyroid (with hypothyroidism, all the thyroid tissue is "gone").

Hyperthyroidism, on the other hand, is extremely common and affects about 10% of older cats. If your cat is showing weight loss despite a good appetite, that should definitely be ruled out.

Michele Goinsalvos said...

I have a 13 yr old male who has been diagnosed with hyperthyroidism, was on Methimazole 10mg per day, 5mg AM - 5mg PM and dosage was just increased to 7.5mg twice a day... He has been on this medication since last summer, has gained about 2 - 2 1/2 lbs. back, coat is still normal, behavior is out the window though, and from reading the other posts here and your responses I gather now it's just part of the illness. However, my cat has also become very aggressive toward his siblings. I have 2 other cats, one 16 yrs and one 12 yrs old. I have so many questions I don't know where to start, but that's because these are my last 3 cats, I had 10, had a property to support them all, but they crossed that rainbow bridge in their own time... but I never had this come up with any of the others. I had 2 of my other cats live to be 21 yrs old and the other 4 who are now gone lived to be between 13 - 16 yrs old. Kidney failure was the culprit for all of them, which I learned is the #1 reason a cat will perish with old age. So now Hunter has this disease, I am treating him with the meds, his behavior is unbelievably bad, terrorizes the other 2 cats, has started spraying my front door, meows like a crazy cat, etc, etc, etc.. and is extremely possessive of me, so, could the meds not be enough for him? the wrong med for him? I take him every 6-8 weeks for a blood test recheck and this is the first time the Dr has said to up the dosage.. Can the meds hurt him with this prolonged use? Also, I've noticed the 16 yr old male now losing weight, am taking him in for a check up next Monday... could it be something in the water where I've moved to? This is just craziness to me to have 2 cats exhibiting the same symptoms.

Jody Taylor said...

My cat was diagnosed with hyperthyroid on her first blood test at 8 yrs old. She has not one of the ten symptoms you describe. I love my cat and will do whatever needs to be done (likely I-131) but I am out of the country and won't be back until september. I can't put this burden on her temporary caretakers. I will come back home if she is at any risk for complications for delaying treatment.

Dr. Mark E. Peterson said...

At only 8-years of age and showing no clinical signs, I would really question the diagnosis of hyperthyroidism. Only 5% of all hyperthyroid cats are less than 10 years of age, so 8 years is young to become hyperthyroid. It certainly is possible, but much less likely than it would be in an older cat.

Almost all hyperthyroid cats will show some degree of weight loss or other signs (eg, increased thirst or hunger). If none of those signs are present, hyperthyroidism is still possible, but it makes the diagnosis less likely.

I don't know what test(s) were used to make the diagnosis of hyperthyroidism in your cat, but all thyroid function tests (especially the free T4) can give us false-positive results. Overall, it sounds like you need to have the diagnosis confirmed by repeating the thyroid tests and making sure that the vet can palpate an enlarged thyroid tumor.

This all said, if your cat does turn out to be hyperthyroid, the condition certainly sounds like it is very mild so there should not be an emergency. The condition is progressive and will worsen but probably not much in only 3 months in your cat, especially given the young age.

Krista said...

Hi, Dr. peterson:

I have a cat who was recently diagnosed with hyperthyroidism (Feb 2013). She is about 14.5 years old. At that time, she had a grade III heart murmur. Since being treated with methimazole(transdermal gel), the murmur is barely audible but still there. Can you tell me how long it could take for the heart damage to reverse? Could this murmur still continue to improve? I am willing to take her to a cardiologist, but the office is about two hours away and the cat freaks out in the car. I mean really FREAKS out. She has be seeing a vet who does housecallls for this reason. I am worried that the trip to the cardiologist could do more harm than good. She has no other signs of heart issues. Breathing rate is about 18-19 when sleeping. She is a bit of a fatty though--slightly over 13 pounds. I am really just curious about how quickly the heart heals itself and how long it can continue to reverse the damage if the damage is reversible. Thank you for your time :-)

Dr. Mark E. Peterson said...

The cardiac signs generally resolve within 3-6 months once the thyroid is well controlled. You may want to give it a bit more time before you bring your cat to the cardiologist, but I'd discuss that issue with your regular veterinarians.

b3d5b110-d17c-11e2-9887-000bcdcb8a73 said...

My 16 year old female cat has recently been diagnosed with hyperthyroidism. She's lost a lot of weight and I was told to feed her as much as she wants. I was feeding her only dry food, but she will no longer eat any dry food. I've started feeding her canned food, but can only give her a half a can at a time as she vomits if she has any more. I am now giving her a half a can four times a day and she is still begging for more food. Is it alright to feed her the canned food and should I feed her more than the 2 cans a day? Thank You. Judi Grant

Dr. Mark E. Peterson said...

Feed your cat as much as she wants, but not too much at once. Dividing the amounts as much as possible will help prevent the vomiting that occurs after eating too much to fast.

Obviously, you are going to have to start treatment for the hyperthyroid state in order to see any significant weight gain. Just feeding her more isn't going to correct all of the problems!

Nicole said...

My cat is about 8-9 years old (she is a rescue so I am not sure exactly what her age is) and was just diagnosed as hyperthyroid. Her TSH was not that bad but her T4 was super high. I am not thrilled at the thought of trying to give her a pill twice a day or putting the topical cream on her ear. What is your opinion of I131?

Dr. Mark E. Peterson said...

In a young hyperthyroid cat like this, definitive treatment with radioiodine is generally the treatment of choice.

I've written tons about radioioidne on this blog, so just keep reading to learn more.

L Baldino said...

Hi my cat is 15 yrs old and i brought her to the vet bc she was vomitting alot (and for awhile i thought it was the treats i was giving her or hairballs) she also was urinating not in her litter box and she became very thin loss of appetite and not drinking much - the vet says she has hyperthyroidism gave me tapezoil for her she kept throwing up though so he gave me mess for nausea - a month later went for check up she lost a pound and was dehydrated - her teeth arent good so he said to start her on anitbiotics for an absess and to stop nausea meds - she is throwing up again - do you think there is something else going on besides hyperthyroidism?

Dr. Mark E. Peterson said...

At 15 years of age, it's not uncommon for hyperthyroid cats to have concurrent disease (kidney disease, gastrointestinal disease, etc). A complete set of blood work, with x-rays and an abdominal ultrasound might be needed to sort this out.

However, vomiting is a very common side effect of the methimazole (Tapazole). If you stop the methimazole for 2-3 days and the vomiting improves, that might be related to the drug.

L Baldino said...

Thank you very much for replying to my question - the only thing is that before starting the tapezoil she was throwing up that is why i brought her to the vet and the only thing that stopped her from vomitting was nausea meds (i dont remember the name) so bc she was throwing up before the tapezoil do you think that is what is making her throw up now - i didnt think it was from the tapezoil bc the color and the amount of vomitting is the same as before taking it - with doing all those other tests what other things could they show is wrong - again thank you - i am very sad and scared for my sweet little girl

Dr. Mark E. Peterson said...

Again, at 15 years of age, it's not uncommon for hyperthyroid cats to have concurrent disease (kidney disease, gastrointestinal disease, etc). A complete set of blood work, with x-rays and an abdominal ultrasound might be needed to sort this out. I am sorry that your cat is sick but you and your veterinarian need to work together to figure out what's wrong here.

Matthew Levine said...

My female cat, Scherzo, is only 4 years old, but she is an over anxious eater and then regurgitates, plus when she cleans herself occasionally her legs and paws twitch as she does it., in addition she also has problems breathing at times, over extending her throat and wheezing. a small massage at the throat and getting her to relax brings her to normal. I am worried this is hyperthyroidism, although recently the drs said she was just and over active eater and has some asthma/allergy issues. Should I be concerned.

Dr. Mark E. Peterson said...

I'd recommend that your veterinarian do a physical exam and thyroid testing to rule out hyperthyroidism. It would be an unlikely diagnosis in a 4-year old cat, but I've seen a few cats younger than 2 years develop this disease.

Jane Doetoo said...

My 17 year old Maine Coon cat has been on insulin for about 8 years and his dibetic symptoms sort of come and goes. He had also previously been diagnosed with FIV; his (new and favored) vet just started him on Methimazole after lab tests; his symtoms included weight and appetite loss and loose stool. Weight is up a bit but stools continue to be loose and his appetite is less than exciting. (Yes, he has been the object of much catering in this area.) First, is there a difficulty with balancing the meds in this instance? And is his reaction to the methimazole common for his age and condition?

Thanks for your help!

Dr. Mark E. Peterson said...

We don't generally see diarrhea or stool problems from the methimazole. You can always stop the drug for a couple of days and see if the stool improves. If it does, then retrial the methimazole and see if the diarrhea comes back.

Again, it's probably not related but no way to know other than trial and error.

Bailey said...

I am so incredibly sad today.

My precious kitty of 13.5 years has very single one of your symptoms listed. In the past year he has gone from 13 to 6 lbs. I finally brought him to the vet yesterday because of blood in his urine/frequent urination. Today the office called-he not only has a bacterial bladder infection (how bad I do not know) but his thyroid level is 24. The nurse said anything under 4 is normal and that my cat is "off the charts". Have you ever come across another cat with such elevated thyroid levels? I'm to start him on his thyroid meds tonight and I'm so fearful of concomitant vomiting-he's already so thin and sick and on antibiotics for his infection. I hate to throw thyroid meds into the mess...

Dr. Mark E. Peterson said...

Serum thyroid values > 24 ug/dl are not that uncommon, but it does reflect severe hyperthyroidism.

This is a treatable condition (medication, surgery or radioiodine) and it's not a death sentence. The prognosis remains good with treatment, even in a cat with severe disease.

Bailey said...

Thank you, Dr. I'm very glad to hear that. I know that urinary tract problems can be a result of hyperthyroidism...however, I wish I didn't have to treat him for both issues at once. My main concern is relieving his pain (Buprenex) and eradicating the bladder infection (antibiotics)...he is crying in the litter box and exhibiting great pain. I'm reluctant to throw the Methimazole into the mix...the last thing he needs right now is to be vomiting. Would I be wrong to put it off until the infection clears?

Dr. Mark E. Peterson said...

The stress of the hyperthyroidism could be making the urinary signs worse. I'd recommend starting the thyroid medication now.

Michele Goinsalvos said...

Dr. Peterson, Could you please explain what it is that happens when the Thyroid Gland is removed? My Vet has suggested that as option for my cat because he's been taking the highest dose of the Methimazole for several months and is losing weight again. I just don't know if doing this surgery is going to be worth it in regards to his quality of life. Will he be able to gain weight without his Thyroid Gland or will he continue to lose it? Is that something that is unique to each of us, where it could go either way?

Dr. Mark E. Peterson said...

With this blog, I describe each of the treatments in great detail. Please review those blog posts and then post another comment if you still have questions.

charonblack said...

Thank you for being so prompt with all your responses to those with questions.

I only include the following because it may factor in to how my little girl has been feeling over a couple of weeks.

I have a nearly five year old medium-hair calico. She has had three litters ovee the past two years. First litter was only one and stillborns. Second litter was five with two stillborn and the other three ended up dying spaced over a few days because she was not bonding with them and consistently left her "nest". The third litter was four and all four are very healthy, active, and mom is very involved. She continues to nurse them even as they are approaching ten weeka oc age.

About two or three weeks ago, Mama began occasionally experiencing loose stools. She also was becoming more vocal about wanting more food. I feed my [total of] three [adult] cats after I get home from work, so it was an odditity for her to want food in the mornings as well. At first I shrugged it off and figured she wanted more because she was nursing. But as the kittens were weaning, her increased appetite became a bigger concern.

I feed all my cats a premium cat food, grain-free. The kittens get the same type, but in kitten formula. None of them are fed human food.

A few days ago, Mama's stools were turning liquid and runny. She was having more accidents and unable to get to the litter box in time in mamy cases. (I live in a two-bedroom apartment with only two other rooms.) When these accidents occured, Mama often became agitates and would run away as if trying to escape from herself.

We also have had some hot days over the past week with highs in the upper 80s and high humidity. Mama began panting a few days ago and seeking out cooler areas such as my shower to find relief. Then she began hiding and attempting to find secluded areas. Since she is a very vocal, social cat, this was a marked change in her attitude. She also has poorer litter box hygiene and finds it more difficult to keep herself clean, especially with her longer fur. She has always been fastidious in her grooming and has never over-groomed, as one of her siblings does when feeling stressed. Mama has become more vocal about wanting to go outside (they are all indoor cats except my one "neighborhood" tom) and has even escaped a few times. When she did, she did not go far and wanted inside quickly, only to turn right around and meow-ll at the closed dooe.

Mama continues to mother her litter and is very attentive to them, even moreso over the past few weeks.

I Googled for "panting and loose stools" regarding cats and the results have pointed to potential hyperthyroidism. Because of the wages my employer pays, I cannot afford to get myself to a doctor let alone a vet trip for my poor dear. However, this is not something I want to simply hope "runs its course". I have my doubts -- a gut feeling -- that it is far more serious than a simple stomach bug especially considering the symptoms.

What do you believe and advise as next steps?

Dr. Mark E. Peterson said...

Over 90-95% of hyperthyroid cats are older than 9 years of ago, so at 5 years old hyperthyroidism would be very unlkely.

In addition, loose stools can be a part of severe hyperthyroidism, but is many hyperthyroid cats this symptom does not improve after treatment, suggesting that it's not always related to the thyroid disease.

charonblack said...

This gives me a great deal of relief. Because of her age, I was hoping that she wouldn't be one of those "rare" cases (I have not had such luck in my personal medical history, so things like this put me on high alert).

Mama still has little ability to control her bowel movements, which is why I thought at first she was becoming dehydrated. Then I noticed the panting, feeling a bony spine when petting her (and she complains when I do), and ongoing hunger.

Many thanks for the reply and insight. It is greatly appreciated.

Maxsmum said...

Thank you for mentioning that miliary dermatitis might be connected to hyperthyroidism.
This is a new symptom for my boy, Max, who is 19. He takes his pills without complaint and responds well to treatment so this skin issue was very concerning but now I am sure my vet and Max can manage this too.

Lisa Ouellette said...

Our 13/14 yr old neutered male tabby (a rescue 10yrs ago) starting exhibiting symptoms 17 mos ago, inclu: weight loss (18 lbs down to 8.5 lbs). 16 mos ago his blood work was clear/normal and neg for hyperthyroid. 14 mos ago we changed from dry to special wet food. This improved his liquid/peanut butter-like stool tinged with blood for a short time, reduced vomiting dramatically, but regurgitation continues at 4:30 am daily (and some time in the afternoon while we're at work). He refuses to urinate in the litter box so we've put sheet plastic under/around it so he won't pee on the floor (3-6 times/day). He yowls at night waking the rest of the family (4 humans & 2 cats) and will pause for food, when given, but resumes shortly after. He is not himself and is all bones; despite feeding him as much as he wants these last 9-10 months (eating 1 can/sitting 2-3 times a day). Our vet mentioned the possibility of Colitis 12-mos ago after several visits, two rounds of steroids and changes to food. His condition has improved little. We love him dearly and don't want him to be in pain. I will have him tested again for hyperthyroidism if you recommend it.

Dr. Mark E. Peterson said...

Well, hyperthyroidism is certainly possible and that could contribute to your cat's gastrointestinal signs. However, based on the dramatic weight loss and severity of the diarrhea, it is most likely that your cat has primary gastrointestinal disease.

Workup, including tests for cobalamin (Vit B12), folate, and pancreatic function, should be done, but an intestinal biopsy will likely be needed for diagnosis,

Melissa Regino said...

Dr Peterson-Our cat Tigger is 16 yrs old, over the last 6mos we've noticed weight loss (he's down to 9.4 lbs) loss of appetite, he's lethargic, has constipation & vomiting. Also his breathing is sometimes short almost labored, when he's resting its almost normal. It seems there's a cycle, about every wk & a half, he will vomit in the evening followed by very hard large stool which has an awful smell to it. He strains & takes several attempts before he can get it out. It's sometimes coated with diarrhea/mucus. (I'm sorry to be so descriptive, trying to give you as much info as possible.) The next day our two he's very lethargic, but still eating & drinking (a lot of water). We've had a full blood panel done & on paper he looks good, full xray & still nothing out of the ordinary. Even though the blood panel was good our vet did mention hyperthyroidism, but also wants us to go to a specialist to get an ultrasound of his heart. Tigger is still very responsive, purrs when we pet him, cuddles up to us, sits in the sun, just not as active. He is using the litter box. Will it do any harm if we start the medication for hyperthyroidism while waiting to get him to the specialist, even though his thyroid was within normal limits? With his symptoms do you think it could be hyperthyroidism? We just want to help him to feel better. Thank you-

Dr. Mark E. Peterson said...

It's unlikely that your cat has hyperthyroidism, at least as the primary problem. The medication is not without side effect, and once started will make diagnosis more difficult.

I would never use antithyroid medicine unless I was certain the diagnosis of hyperthyroidism was certain.

anna said...

My 12.5 year old cat was recently diagnosed as hyperthyroid (about five weeks ago). She had a T4 of 5.3, significant weight loss 12 pounds to 8 pounds, increased appetite and thirst, and some increased activity. She has been on methimazole for about three weeks (2.5 mg twice per day). I weighed her today and she has lost more weight (now weighs 7.4 pounds). Does it seem like this could be from hyperthyroidism or does it seem like maybe something else is going on here? We are waiting on the most recent blood test results.

Dr. Mark E. Peterson said...

Of course something could be going on with your cat, in addition to hyperthyroidism. I'm assuming that your vet did a thyroid profile (or at least a T4) as well as a serum chemistry panel. Wait for those results and talk to your vet about your concerns.

If you aren't doing so already, think about feeding a high protein diet, which may help slow or stabilize the weight loss.

Vicki said...

My cat is 13 years old and was diagnosed with hyperthyrodism about 15 months ago. I tried him for a while on tablets but eventually he had an operation and everything has been fine except he is now constantly grooming to the extent his has little bald patches, he has a crusty scabs over the lower part of his body, constantly scratching and shedding fur everywhere. The vet diagnosed a flea allergy and gave a steroid injection which worked for a couple of weeks but things are now just as bad as ever. I am treating him with a flea treatment every three weeks and have used a household spray all over the house and furniture twice in the last three months but his condition has not improved. Is it possible that his thyroid problem has returned?

Dr. Mark E. Peterson said...

Yes, it is possible that the hyperthyroidism has relapsed, especially if only part of the thyroid was initially removed.

You need to have your cat's thyroid function rechecked, which should be done at least twice a year after surgery anyway.

admin said...

My cat is 15 and he has been losing a lot of muscle mass over the past 6 months but not weight (around 7 pounds). He is borderline on some of the other symptoms. He repeatedly tests normal on thyroid tests including additional Free T4 and parathyroid. The vet also says his thyroid is palpable. He is on BP meds and has a slight heart murmur. Do you recommend that I keep doing hyperthyroid follow up tests? What do you suggest?

Dr. Mark E. Peterson said...

At 15 years of age, your cat needs to have a thyroid test(s) at least once a year, even if a thyroid nodule was not palpable.

Loss of muscle mass, hypertension, and heart murmur, etc could be hyperthyroidism but could be due to other problems as well. If your vet doesn't have a diagnosis, continued monitoring and testing to determine what is going on is certainly indicated.

Heather Hoesly said...

Anakin is 17 years old, blind, wanders around in circles, is confused, no-longer has solid stools, has slightly increased water consumption and his appetite is normal. His fur has gotten dull and he no longer cleans himself. He has started sleeping in his downstairs litter box. He only urinates in his upstairs box and only poops outside the box. He sleeps the majority of the time and is not agitated or hyper. Could this be hyperthyroidism?

Whitney Kurtz-Ogilvie said...

Our sweet 15 year old cat was diagnosed with hyperthyroidism about four months ago, and it's been a frustrating roller coaster ride ever since, trying to help her recover.
Our vet started her on methimazole liquid, and she did beautifully for a few weeks, then started having serious appetite trouble--hardly eating anything. We took her back in for bloodwork and it showed that she had reacted too strongly to the methimazole and was now very HYPOthyroid. Our vet took her off the methimazole temporarily, to let her T levels get back to hyper. Then we started her back on the medicine at a half-dose. Again, for a couple of weeks she did really well, and then boom, lost her appetite again b/c she'd overreacted and gone hypo. After three weeks off the methimazole AGAIN, we just started her back on the methimazole at an even lower dose (three days ago). Her appetite is still very low. Our vet has done a full blood workup on her twice--no kidney trouble or liver trouble, just the thyroid trouble. I'm just wondering, have you seen this kind of overreaction to the methimazole in cats, and do you have any suggestions for a.) making sure we get the right dose and b.) helping to stimulate her appetite? We've tried everything we can think to try (and we've got her on famotidine twice daily to try to prevent nausea). Thank you for this wonderful resource. :)

Dr. Mark E. Peterson said...

Very unlikely, but you definitely need to see your veterinarian to have your cat checked.

Dr. Mark E. Peterson said...

Dear Whitney - methimazole is not a good treatment for some cats, and that appears to be the case with your cat.

I'd recommend that you talk to your veterinarian about one of the other treatment options that we can use, such as radioiodine, surgical thyroidectomy, or use of a low iodine diet.

Gatorgurl07 said...

Dr. Peterson - your article and blog have answered so many questions for us and helped alleviate our concerns about the various symptoms of the disease, and side effects of Methimazole.

Our 16 year old cat was diagnosed 2 years ago and is no longer able to tolerate the meds.

So glad there is an alternative. He is scheduled for his Iodine-131treatment today. Thanks for making this information available.

Dr. Mark E. Peterson said...

Thanks for your kind comments. Good luck to you and your hyperthyroid cat!

pumpkin45 said...

Dr Peterson~my 9 year old cat has started defecating outside her box in strange places and its soft sometimes blood drops are near it. She has also developed twitching and having issues with her mouth like her teeth are bothering her. I have had her to 4 or 5 different vets and changing her diet has not helped. Blood work was done but came back negative. I don't have the money to have a colonoscopy done which was the next recommendation. Please advise I am getting very worried. Thank you.

Dr. Mark E. Peterson said...

If the thyroid testing was normal, then your cat is not hyperthyroid. The clinical signs don't appear to fit hyperthyroidism anyway...

This sounds like IBD (inflammatory bowl disease). I'm not a GI expect but your veterinarians should be able to recommend a specialist who can help you and your cat.

Shauna Ward said...

I have a beautiful calico cat that is 17 1/2 years of age. She has dropped a few pounds over the last few months, enough that I can feel her bones when petting her. She has an increased appetite and seems to eat and drink all the time. Last week I took her to her vet to check her out because she is having labored breathing, sometimes breathing with an open mouth and I can hear wheezing at times. The vet diagnosed her with feline asthma. Put her on prednisone, which I have been giving per instructions. After several days there was no improvement in her breathing. So they added Theophylline. She is still having labored breathing, but no wheezing. She is still very loving, purrs and cuddles, but I do notice when I pet her or scratch her belly, this seems to cause her breathing to become even more labored. She did have blood work to check the liver and kidneys and that all looked great. Does what I've stated sound like she could have hyperthyroidism? I plan on taking her back to the vet this next week for x-rays but wonder if I should mention testing her thyroid. I don't know what else to do, this is heartbreaking.

Dr. Mark E. Peterson said...

Hyperthyroidism will develop in 10% of cats over the age of 10 years of age. So every cat that has reached the age of 17 years should be tested for hyperthyroidism, especially when there are clinical signs (weight loss, increased appetite and thirst) that are consistent with that diagnosis.

I'm not an expert on feline asthma, but it seems a bit strange to me that your cat would first develop asthma at this age. Talk to your vet or get another opinion!

Dee said...

I have a 14 year old with hyperthyroidism.The first vet had him on 2.5 mg felimazole once a day. When his associate took over, she immediately changed him to 2.5 mg twice a day. At the last blood check she said his kidney numbers were up, but to keep him on the same dosage and call if there was any problem. A couple weeks after that he was sleeping all the time with little interest in anything. I opted to cut back to one pill a day, and he seems more normal now. I plan to take him back in a couple weeks to have blood work checked. What is a normal dosage of this drug, and what would a normal thyroid panel be like? She has not given me copies of the labs, but I plan to ask for them next time, and would like to know what to look for. He had been 10 lbs, but drpped to 8.5. I think his weight has probably come back up a half lb or so. Thanks.

Dr. Mark E. Peterson said...

The dose needed for hyperthyroid cats can vary between 1.25 mg per day up to 20 mg per day. But it certainly sounds like your cat is on too much of the drug.

We want the total T4 value to be in the middle of the normal range (see my other blog posts where I discuss methimazole treatment!).

Helen said...

I have a 14 year old cat who was fine upto 5 months ago. He started with an increased appetite and was still very playful. He started to be sick and I took him to the vet to have dental work. He seemed fine but since then he has 2 ok days and a day when he vomits. The vet took blood twice which showed elevated white cells and the xray and ultrasound were normal. They gave him more antibiotics and said he may have a food allergy. The prescribed food he would not touch and he was losing more weight so I purchased good quality trays of food from lilys kitchen range. He seems fine after vomiting and he doesn't bring it all up but I don't know why he has this pattern of vomiting.i have spent £800 in the past few months and am still none the wiser. Do you think he needs a specialist?

Dr. Mark E. Peterson said...

Yes, a veterinarian specializing in internal medicine or gastroenterology would be best.

meadowshadow said...

Hi Dr. Petersen,
My cat is almost 13, and has the following symptoms:

-blood in urine
-severe hunger and thirst (getting up on the table and licking the family's plates when they're out of the room)

The blood in the urine has been going on for about a month; initially I thought my three year old was having nosebleeds from the dry air but it turns out it was my cat peeing outside the litter box. Otherwise she seems to feel ok and is not hiding or anything like she normally does if she is sick with an infection. Could this be hyperthyroidism?

Dr. Mark E. Peterson said...

Of course this could be hyperthyroidism. You need to have your cat examined and the diagnosis confirmed by running at least a serum T4 concentration.

Ann Paul said...

Hi Doctor Peterson, I have a rescued cat who had been living in ab abandoned theatre. He shows all the signs of hyperthyroidism right down to fast heart rate, elevated temperature, increased apetitite, nervous anxiety,...only he is gaining weight, quiet and his coat has actually become more glossy and soft than before. He has been vomiting twice daily since 3days at approximately the same time:once in the wee hours of the morning and the other in the after noon...sometimes even once in the evening. .could you tell me what might be wrong? M extremely worried.

Dr. Mark E. Peterson said...

Doesn't sound like hyperthyroidism, but honestly, this could be any from a nervous stomach, inflammatory bowl disease, or GI parasites to serious metabolic disease or worse.

Bottom line -- You need to bring your cat to a veterinarian for an exam and some basic tests. If you can, it wouldn't hurt to bring in a stool sample so they can do a fecal analysis too.

Paul said...

How long after radioiodine treatment will symptoms of the hyperactive thyroid begin to resolve ? Also wondering if muscles effected by wasting will return to normal ? Thanks, Paul Scull

Dr. Mark E. Peterson said...

Most cats will have a normal serum T4 concentration by 30 days after I-131 treatment, although some cats, especially those with more severe disease, can take longer to normalize. About 2-5% of cats will remain slightly hyperthyroid and may need a second treatment.

Once euthyroidism is reestablished, most cats will gain weight within a few weeks (certainly by 2-3 months). If marked muscle wasting has occurred, it may not be possible to completely regain the lost muscle. Remember that it will help to feed a diet that's high in protein (40-60% of calories), relatively low in carbs (<15% of calories), and high in fat (40-60%).

For more about diet, see my past posts on how to feed cats with hyperthyroidism.

Dr. Mark E. Peterson said...

Most cats will have a normal serum T4 concentration by 30 days after I-131 treatment, although some cats, especially those with more severe disease, can take longer to normalize. About 2-5% of cats will remain slightly hyperthyroid and may need a second treatment.

Once euthyroidism is reestablished, most cats will gain weight within a few weeks (certainly by 2-3 months). If marked muscle wasting has occurred, it may not be possible to completely regain the lost muscle. Remember that it will help to feed a diet that's high in protein (40-60% of calories), relatively low in carbs (<15% of calories), and high in fat (40-60%).

For more about diet, see my past posts on how to feed cats with hyperthyroidism.

Wendy Stotz said...

Several days ago my 12 yr. old cat started vomiting after eating, most times it was barely digested food. It progressed to where whe wouldn't eat or drink yesterday and was acting sluggish and ill. Took her to the vet anticipating a blockage or GI issue. Blood work came back normal except elevated T4 ( 5.8 ul/dl), low phosphorous ( 1.9 mg/ dl), low platelet @ 251 and monocytes elevated @ 4.7. Vet prescribed methimazole but I'm concerned that perhaps the thyroid is not the problem, or not the only problem. Can hyperthyroid cause acute onset of these symptoms? Will the pills help when I've read they increase stomach upset? Can T4 be elevated due to another illness unrelated to actual thyroid, a false positive? Also, one of the analyzers says the specimen had 1+ lipemia but a different analyzers called it 0. I the specimen is lipemia won't it be that way for all tests/tubes. Confused and wondering if I need a second opinion.

Dr. Mark E. Peterson said...

Hyperthyroidism can cause vomiting, but the appetite almost always remains very good to even increased. Your cat may be hyperthyroid, but I'd worry that something else is causing her not to feel well. We certainly wouldn't want to start methimazole in cats that aren't eating because that may make the appetite worse.

Talk to your vet to make sure everything else has been ruled out and to make sure that a thyroid nodule was palpated. If not, we may want to confirm the diagnosis of hyperthyroidism.

Denise Risser said...

Lately my cat has been pooping outside her litter box. When I google this I find references to thyroid problems. She doesn't really have the other symptoms of hyperthyroidism, but does often have diarrhea and it seems to smell more than usual.
She is an indoor/outdoor cat and we live in Indiana so we only notice this problem in the winter when she can't go out as much.
We thought it might be a behavioral problem but can't seem to find a pattern.
She has a "favorite" place that she does this - in the dining room at the bottom of the stairs (on the carpet). She occasionally does it other places in the house, but that is rare. She also very occasionally will poop in her litter box.
I have tried adding another litter box, using "cat attract" litter, spraying "dumb cat" spray. Still doing all these and there is no difference. Some days I'll come home from work and find 5 piles, other times none. She also does this in the middle of the night.
She was treated for pancreatitis 3 months ago and worms 2 months ago.
Help! Does she have a thyroid issue that is causing digestive issues? Otherwise she is a really nice cat!

Dr. Mark E. Peterson said...

If inappropriate defecation with occasional diarrhea are the main signs, that's unlikely to be due to hyperthyroidism.

However, I would recommend that you have your veterinarian palpate for a thyroid tumor and run a serum T4 to rule out hyperthyroidism.

Jen said...

My vet missed the diagnosis of hyperthyroidism and I am in need of some guidance.

I noticed my 14.5 yr old cat was drinking more and appeared to by losing some weight. Upon research it looked like most likely diabetes or kidney problems. I switched her to wet food and planned to take her to the vet withing a week or so when I would be on break from xmas.

Over the break she had a coughing episode and we noticed funny respiration / breathing or heart rate - noticeable just under her ribs. Took her to the vet the next day. He tested her for both diabetes and kidney, blood tests came out normal. He said he could hear fluid around her heart/lungs and she either had an infection or a tumor. He attempted to take and xray but said he couldn't because she couldn't breathe when placed on her back. He put her on an antibiotic and 2x daily diuretic.

I brought her back in a week and the vet said the heart sounded much better / clear. However she had dropped a whole pound in weight. He said probably the diuretic and reduced her dosage to once a day. He also told me to put her back on dry food.

Two weeks later I returned with her to the vet - she was losing more weight and the observable abnormal heart rate/respiration was visible again. She had lost yet another pound. Now down to 7lbs. The vet just told me that she was dying and to prepare to make a life decision in the next few days to week or two tops.

Devastated,I brought her home and began feeding her whatever she wanted - turkey deli meat and back to wet food. She kept begging over and over for the wet food. Back on the wet food it was much more obvious that she was wanting to eat all of the time. I thought that was so unusual for a cat that was losing weight rapidly and supposedly dying. I researched it and discovered hypothyroidism.

The next day I called my vet and asked if her thyroid had been checked. No. I couldn't believe something that should have been so obvious to him had not been checked. I brought her in and asked her to be tested. My poor cat went into severe respiratory distress from the stress of having her blood drawn. She could barely breathe and I had to hold her and try and put oxygen on her. This event lasted at least 30 minutes. I was beside myself watching my cat suffer. And was preparing to tell the vet he could go ahead and put her down, I couldn't possibly make her suffer like this. Then he told me the results of her thyroid test - 7.0!

Yes she was hyperthyroid. When asked about treatment - radioiodine - he said she was too old, most cats are about 8 years old when successfully treated. I knew this to be incorrect due to my research the night before.

I left with 5mg pills of methemizole divided into half - morning and night. He gave me 8 days worth, thinking I would be back to have her put down. He acted as if the hyperthyroidism is in addition to a heart problem, not the other way around. he just doesn't seem educated or informed on the subject.

I need to take her to another vet to make sure she is being properly treated. She is still on once a day diuretic and I don't know if that is correct of if she should be taking anything for her heart. I'm hoping the methamizole will stabilize her enough so that I can take her to the vet soon without risk of her going into respiratory distress again. How long does it take on the medicine before symptoms improve? She still has the visible funny breathing/heart rate noticeable below her ribs so I'm terrified to stress her into respiratory distress.

I believe she has had the hyperthyroidism for at least 6 months. The weight, drinking, eating issues only noticeably began in December. However several months prior I had noticed how she had been acting like a kitten again - chasing things around the house and chasing her tail. I thought it was cute and maybe senility - I had no idea it was the sign of something going wrong. Is the heart problem most likely permanent now?

Dr. Mark E. Peterson said...

Once hyperthyroidism is controlled, the associated heart disease generally improves and sometimes resolves completely. You really need to see a cardiologist, however, to determine what treatment is needed,

In my opinion, your cat is not too old for radioiodine - the averaged cat that I treat is 13 years old. And some cats are much older and do fine.

Eighthambiguity said...

Hi. My cat is 14. She eats regularly, urinates, and passes stool normally. She sleeps a lot, but is still active and plays. Her weight is steady. She's also almost entirely deaf, which seems to have happened over the last year or so. Problem is, she YOWLS. Not at night--never at night--but in the middle of the day. She'll stop if she sees me. I have no idea what is going on with her. Is she in pain? She has no symptoms of illness besides the yowling, which lasts about 20-30 seconds. Then she stops and goes to sleep. Or sees me and starts purring. Could this be a thyroid problem despite having almost no traditional symptoms?

Thanks so much.

Dr. Mark E. Peterson said...

Hyperthyroidism is possible but not likely. Talk to your vet so that they can do a physical exam and run a serum T4 level.

anniestime1 said...

I have three cats, but my 11.5 year old black short hair male started spraying, playing like a kitten, whining, and trying to steal food out of peoples hands/ So I took him to the vet. He was diagnosed with hyperthyroidism late November 2013. He has had a heart murmur since 2007. Tapezole was not tolerated, even at reduced dosages, so we started Hills Y/D soft and hard food. I have two other cats and nobody liked the food and it was wasted. I discontinued Y/D 3 weeks ago. Took spike to a new vet this past Saturday and received an exam specific for Radiocat for the I-131 treatment. They couldn't give me an appointment until March 10. Today, for the first time, he did not greet me at the door, and has no interest in eating. He is hiding, either in my closet or under my bed. He has lost a lot of weight and appears to be weak. I scheduled the radioactive treatment on 3/3 at Angel Memorial...but I am worried that he might not snap out of this lethargic behavior. If I-131 treatment is so successful and so needed these days, why is it not so readily available? I am so afraid that he is in pain and will not make it until the 3rd. I feel so helpless...

Dr. Mark E. Peterson said...

If your cat is lethargic and not eating, that is a sign that something else is likely developed. You need to have her checked ASAP. Call your veterinarian.

Mitzie Be said...

I have a 16 year old cat (17 in June). Last year he developed Hyperthyroidism and was treated by surgery. However after repeat bloods to check his TS4 levels were normal I was presented with a bill for a biopsy. I was informed that my cat had adenocarcinoma and his prognosis was not good. Due to his age I was advised not to go down the route of aggressive treatment and to opt for conservative care. Which I agreed to. However have noticed he has lost a lot of weight (only noticeable after I had his fur trimmed as it was matted). He is hungry all the time and eating very well but not putting on weight. And he has become skittish - jumps or runs at any sudden noise. To me these symptoms would indicate another bout of hyperthyroidism (remaining gland)rather than cancer. Can you please advise me of the symptoms of cancer? I was told as he had cancer of the thyroid he could not get another bout of hyperthyroidism symptoms. Please advise. Many thanks.

Dr. Mark E. Peterson said...

When cats develop thyroid carcinoma, the prognosis is not terrible - they don't usually die of metastatic disease. The tumor can become very large and may extend into the chest, but usually doesn't result in death of the cat per se.

The most common cause of death in these cats is uncontrolled hyperthyroidism. You need to verify that your cat is indeed caused by hyperthyroidism and start medical treatment if that is the case.

Gina68 said...

Hi Dr Peterson-I seem to have a bit different scenario that the ones I'm reading. 11 yr old female cat with weight loss. Currently weighing just under 8 lbs, from around 11 lbs. Vet did thyroid test and figures were >10. The doc who saw her that day stated the thyroid was swollen on one side. We began administering topically a compound drug Methimazole 5mg 2x daily for 2 weeks, and I opted to schedule surgery to remove affected portion of thyroid. Today was her surgical date. *Diff doctor/but same clinic than who initially diagnosed. He advised me that he did not note any such swelling when he examined her prior to procedure. He decided to make the incision and have a look. He said the thyroid glands appeared to be healthy with no swelling or inflammation. At that point, he closed her up and decided to perform another thyroid test. This test came back >10 as well. He could only assume that perhaps the gland further down in the chest may be the source & referred me to an internist. We agreed that it would be a good idea to give Felimazole 2x daily orally; he expressed that there was a lot of debate over whether the topical version was absorbed fully/properly. He felt ultimately (and a few thousand $ later)..the internist would want to run more costly tests and eventually radioactive iodine. Financially this is not feasible. Is there anything else that would cause thyroid levels this high that I could specifically get checked? I must say this doc never charged a dime for the procedure, the labwork performed today and even gave me a few weeks worth of pills for $0 (how great is that?) Thank you in advance for any wisdom/insight you can provide--Gina

Dr. Mark E. Peterson said...

Sounds like the T4 was done in-house; many of those machines are inaccurate. I'd recommend a repeating a T4 and free T4 and send the blood to a veterinary lab. If both values are high, then your cat is hyperthyroid.

Sarah Schaale said...

Hi Dr. Peterson,
Does the T4 test ALWAYS confirm hyperthyroidism? My 12.5-year-old cat has every one of the symptoms you list here, except respiration (at least that I've noticed) and vomiting (unless she eats too fast, which we've controlled with smaller meals). She's had a full senior panel of bloodwork done, and the vet says everything is normal--thyroid, kidneys, etc. She's also had an ultrasound done to rule out any inflammation in her intestines since her first symptom was chronic diarrhea. The one thing he did say was she has slightly elevated pancreatic numbers, but she doesn't have other symptoms of pancreatitis, like vomitting or decreased appetite. So right now he basically had no solution, but she's typically been a 12-3 pound cat, was down to 8 lbs. a year ago and this week weighs just under 6 pounds :(
I'd like to get a second opinion, I'm just not even sure what to ask.

Dr. Mark E. Peterson said...

A total T4 determination will be positive in over 90% of hyperthyroid cats, but not all. That said, cats that have normal T4 values have very mild signs (little weight loss) so that doesn't fit in your cat. If diarrhea is the main sign, it's likely that the GIT is the problem. You may need an intestinal biopsy to figure out what's wrong. Talk to your vet about what to do next.

LizzyNC said...

I have a 16 year old Siamese who has had blood tests showing normal t3 and 6 points above normal range of t4. She drinks a lot more recently and urinates often, she yowls (some of this started when our 14 year old died last year but has gotten worse. Her other blood test are within normal range. Vet says that urine isn't really concentrated properly though. She still eats well, but we have had to add places for her to get on bed and sofa. I don't remember this happening to other Siamese cats we have had. Could she still be Hyperthyroid? Should we treat for a few months to see? Vet is very young and I'm not totally comfortable with him. Help!!!
Lizzy for NC

Dr. Mark E. Peterson said...

Of course your cat could still be hyperthyroid and probably is, given that the T4 is slightly high.

I'd repeat the thyroid tests (including a free T4) in a month or two. Ask the vet at that time if they can feel a thyroid nodule. If your cat is hyperthyroid, most have a palpable nodule on the thyroid.

JennD said...

My cat is 8 years old and was constipated so I took him to the vet they gave him some laxitive meds and told me to change his diet to wet food he was on dry. When the presciption ran out to give him metamucil to help with constipation. I did that & still gave him a bit of dry & mostly wet. He is fine for about 4-6 days but doesn't pass a stool. They the day he does he has extreme vomitting & diarrhea. Now he's hungry all the time (like he can't get enough to eat)he lost some weight but not a lot. He is still active but his coat is not the same & he has started to meow alot during the day and early morning. Do you think it's food allergy or change in diet or hyperthyroidism? Thank fo your time. Jenn

Dr. Mark E. Peterson said...

Do you really expect me to diagnose or exclude hyperthyroidism based on a history? Almost all feline diseases that occur in middle-aged to older cats can mimic hyperthyroidism. Have your vet palpate for a thyroid tumor and have them run a serum T4 determination to rule out hyperthyroidism.

Rebecca Vassie said...

Hi there. My cat who is less than a year old has just been diagnosed with hyperthyroidism (by a vet who looked it up on the internet) but did not show any physical signs of an increased size thiroid. I will be shortly be taking the cat to an alternative vet for another opinion as I am not yet convinced this is the case.

Last month she gave birth to a litter of kittens (4) and has only in the last two weeks dropped dramatically under weight. She is very angry and spending a lot of time on her own, and seems to be in pain but is eating normally, which has always been a lot. In the meantime, the vet did de-worm her (which was only done last month) gave her a course of vitamins and a strong broad spectrum antibiotic shot, so I am monitoring her behaviour for a week, before I seek alternative advice.

I live in Uganda, where there is little help given in terms of vets. There are few ways to obtain specific medication she may need if this is the case. Therefore, before I get too worried, just wanted to ask if this sounds normal after young cats give birth?

I understand you are not able to diagnose over the internet, just wanted a little advice before I get too worried. Is this maybe a case of guessing, or is it likely? From what I have read, it seems to affect much older cats.


Dr. Mark E. Peterson said...

Over 95% of cats with hyperthyroidism are older than 9 years of age. It would be almost impossible for a cat less than a year of age to have hyperthyroidism.

Rebecca Vassie said...

Great! Thats what I was looking for!

sue09090 said...

My 18 year old cat has developed a skin infection which now covers 70% of her skin. She's been having medication for hyperthyroid for nearly two years now. She has all the classic symptoms and has regular blood tests. Her skin is so sore, she's had four weeks of antibiotics but it they haven't done anything. Is there anything the vet can do? Or would it be kinder to let her go, as much as it will break my heart.

Dr. Mark E. Peterson said...

Cutaneous signs like you describe do not occur with hyperthyroidism. In addition, your cat is already being treated for hyperthyroidism. Sounds like a dermatologic consult (and maybe a skin biopsy) is indicated.

In any case, this is unlikely to be thyroid-related.

Cara Emberson said...

Hi Dr Peterson
I am currently looking after my friends cat who has been unwell for some time now.

My friend has been to the vets on several occasions for tests and different diets and medications. Her vet said that they had no idea what could be wrong with her and has told my friend to treat her as palliative care as she is quite a happy affectionate cat and doesnt appear to be in any serious pain.

Having found your blog we are certain that she might have hyperthyroidism. She began with really bad itchy and scabby skin, lost a lot of weight and coat condition and unable to gain weight, pronounced swallowing, very thirsty and hungry and I would say a bit lethargic but I might be wrong. I've just discovered a fair amount of blood in her faeces and didn't see it mentioned above.

I have her for two weeks, firstly do you agree that she may have hyperthyroidism? is blood in her faeces common with the condition? and she is currently eating dry food but asks constantly for other food is there anything I can do with her diet to make her more comfortable or to help?
Thank you .. Cara x

Dr. Mark E. Peterson said...

First of all, it the cat a senior (older than 10 years). If not, hyperthyroidism is unlikely.

Secondly, weight loss despite a good to increased appetite are the major signs. Bad itchy and scabby skin, pronounced swallowing, lethargy or blood in the stool are not signs that we expect to see.

You cannot diagnose this condition on the basis of the cat's signs alone since they mimic those of hundreds of other problems. Have the vet do a T4 determination.

Cara Emberson said...

Thank you Dr Peterson. I think she is 9 years old. Too young to be so unwell poor girl.

I will get my friend to request it from her vets on her return from holiday.

Thank you for such a useful and informative blog. xx

C&M said...

Dr. Peterson,
I have a 12 year old cat that was diagnosed April 18 with hyperthyroidism and is on medication now. He was retested May 12 and his To level have come within normal range, but for the past two days his mood has deteriorated dramatically. He does not have an appetite and sleeps all day and night. Much more than normal. He was a very social cat up to this point, and now seems very depressed. He weighs 8.2 pounds but is very skinny and has lost 1 pound since April 18 checkup. I have tried pouring broth on his food. And switched to all wet diet to try to get him to eat. Do you have any recommendations or advice? Thank you for your help

Dr. Mark E. Peterson said...

Your cat should be monitored at 2 and 4 weeks after starting treatment, looking at the T4 and renal function at the very least. Talk to your vet about a recheck ASAP.

Lorraine Mckessick said...

Good Evening, my cat was diagnosed with hyperthyroidism and is on medication now for over 6 months I have been away for 5 days but partner has been looking after him while I was away when I got back I noticed that my cat's hair has started matting again, tonight he will not take his tablet and hasn't eaten today and he is having problem breathing panting very fast, I am going to take him to the vet in the morning but could this be a heart problem? My cat also hates the car journey and he also just about died once taken him to vet through panting etc he hates the journey. Please advise if I should be asking them to check anything in particular as it was me that asked for him to be checked for hyperthyroidism when his CRF came back as normal. I really do not want to have to put him through anymore pain but I will not give up on him. Thanks Lorraine

Paula Hudson said...

Hi Dr. Peterson. My 16 year old female cat was treated for a UTI with a shot back in December and in March it appeared to have returned symptom wise with urinating in sink etc. The vet allowed me to pick up some pills to try that time for seven days and it seemed to work BUT she seemed to have gotten it again recently. Got the pills one more time for 10 days. Actually this last time after I got the pills I noticed other behaviors starting with increased appetite and thirst so started researching and came across hypothyroidism and she has all the symptoms. I am taking her to Vet next Monday but my question concerns the kidneys connection. With her age is it possible her kidneys are starting to shut down and will the treatment for hypothyroidism fix that. I am debating having her put to sleep be cause she seems so uncomfortable. She just finished her pills and her urine issues seem better but I wonder if just temporary. Thank you.

Dr. Mark E. Peterson said...

The first step would be to talk to your vet and confirm hyperthyroidism (not hypothyroidism). Your cat does not have all the signs of hyperthyroidism since a UTI isn't normally part of the picture.

Dr. Mark E. Peterson said...

Dear Lorraine,

If you cat isn't eating that is a very bad sign. You need to have your vet check your cat ASAP.

Lorraine Mckessick said...

Dear Dr Mark,

I took my cat to the Vet first thing this morning and was advised he was not in a good way the vet completed a chest drain and have been given Nelio & Frusemide Tablets to give to Cat along with his felimazole. He is back at the vet tomorrow for check up but not 100% that the drain has worked as his breathing still seems a bit quick. He has eaten a little bit tonight but just am not sure if I am doing the right thing for him. I do not want to see him in any discomfort/pain but I also don't want to give up on him thanks Lorraine

Dr. Mark E. Peterson said...

The prognosis doesn't sound too good, but you have to talk to your vet about your cat and what to do. I can't give a diagnosis or prognosis over the web!

Susan (aka qwho) said...

My 13 year old kitty, Topaz, is at the clinic now. today she had her scan and blood pressure, tomorrow the I-131.

Her blood pressure was a bit high, but she said that is typical, and they will treat today and I can stop in 30 days if it is back to normal after 30 day bloodwork.

also said her urine concentration is off. How worried should I be about that? I guess the hyper thyroid causes the actual numbers to be artificially low and after treatment they will rise, and it will just be a matter of how much and if they stay in normal range or not. and that dietary changes may help.

anything you can add or take away from what I posted? thank you.

Dr. Mark E. Peterson said...

I would guess that they mean that the urine specific gravity isn't very concentrated. Unless your cat's kidney values are high, the urine concentration doesn't mean very much. I'd recheck everything in 1 and 3 months and go on from there.

Susan (aka qwho) said...

thank you so much! I am anxious to get her back home in a few days and hope there is no underlying kidney problems that the hyper thyroidism was masking. she did say her tumors (one on each side and two at the back of her throat are small.)

MAY said...

Hello, my thirteen-year-old kitty was diagnosed with hyperthyroidism about a month ago. He has been on methimazole for a month and his thyroid level is now back to normal and he seems like his old self again. I'm writing because what took us to the vet's originally was that my cat had a hind leg collapse that lasted for one to two seconds, which made me think it was a heart issue. But he has since had an echocardiogram which came out normal and the cardiologist could find no cardiovascular cause of the event. My question is, could the untreated thyroidism have accounted for that collapse?

Dr. Mark E. Peterson said...

Hind leg collapse is certainly an unusual sign, and in general, is not associated with hyperthyroidism. That said, the fact that your cat is better is strong evidence that somehow the thyroid condition caused it.

Hyperthyroidism can cause weakness due to a myopathy (usually associated with muscle wasting), development of hypokalemia (low potassium), or cardiac disease. The heart problem may have been an arrhythmia, which has now resolved after the T4 has been lowered.

Dr. Mark E. Peterson said...

Hind leg collapse is certainly an unusual sign, and in general, is not associated with hyperthyroidism. That said, the fact that your cat is better is strong evidence that somehow the thyroid condition caused it.

Hyperthyroidism can cause weakness due to a myopathy (usually associated with muscle wasting), development of hypokalemia (low potassium), or cardiac disease. The heart problem may have been an arrhythmia, which has now resolved after the T4 has been lowered.

Asya Ludmilova said...

Dr. Mark E. Peterson
I'm from Bulgaria,
My cat too slow diagnosed with hyperthyroidism
6 months after I sought help from a doctor
taken one week 2.5 mg metizol -of 12h.
My cat is cardiomegaly,heart rate of 190-220,respiratory rate 25 per 1min.
Please reply to me which are the first visual signs of improvement and how long intake metizol.

We know that after two weeks we need to test T4,But how do I know before the test that is influenced by metizol.

Dr. Mark E. Peterson said...

As the high T4 and T3 normalize, the signs slowly abate. I doubt if you are going to see too much improvement before 2 weeks. The first thing we see is less hyperactivity (if present).

Asya Ludmilova said...

Thank you very much for the reply
In Bulgaria there is no available treatment with radioactive iodine.
Can I combine metizol with homeopathy?
Do you have any observations and if yes, what is homeopathic medicine?

Dr. Mark E. Peterson said...

See my post:

Asya Ludmilova said...

Thank you very much Dr.Peterson!

Asya Ludmilova said...

Hello again,Dr.Peterson!
In Bulgaria we can examine only FT4
I have no choice and are therefore guided by these values
My kitten they-FT4≥77.4
Our doctor does not have enough experience with similar diseases, but really doing everything he could.
As he says early in the second week,
do control a FT4-due to the fact that my cat responds slower.
My question to you is-Is it possible to make mistakes by delaying another week study?
Thank You!

Dr. Mark E. Peterson said...

Using a free T4 to monitor should be fine. We generally recheck the cats in 10-21 days. It would be better to check earlier and more frequently (every week) but this is generally not practical or feasible.

Asya Ludmilova said...

Тhank you infinitely!
You have no idea your professional opinion, how much it means to me.
At the moment I have a problem finding a suitable food for her.
I read your blog and compared it to identify what to look for.
Unfortunately, here again not available diet Y/D
Unfortunately, my country has no established methods for the treatment of cats with hyperthyroidism.
Thank You!


Dr. Mark E. Peterson said...

Read my other blog post on diet:

MAY said...

Dear Dr. Peterson, thank you so much for this blog. My thirteen-year-old cat, diagnosed with hyperthyroidism about six weeks ago, is now doing very well after being on methimazole transdermal cream, twice a day, for the last six weeks. The vet said his thyroid levels are now normal. Here is my question: I'm supposed to go away for about forty-eight hours next week, and I'm not sure my cat will allow the cat sitter to apply the transdermal meds to his ears. Would going without methimazole cream for two days cause a cat's thyroid levels to rise to a harmful level? Thank you.

Dr. Mark E. Peterson said...

Why are you posting a question on treatment here? Have you read my many other blogs that deal with treatment?

If you don't give methimazole for 2-3 days, the T4 value will again go up into the hyperthyroid range. So this is never recommended. That's the problem with methimazole - doesn't cure, just controls but the thyroid tumor remains.

MAY said...

Yes, thank you; I'm just so new to having a hyperthyroid kitty that it's taking me some time to read everything about the condition, hence my question. My apologies if I posted my previous question in this forum if I shouldn't have done so, but thank you for answering it. I have a lot to learn!

Dr. Mark E. Peterson said...

Here's a link to all of the other posts I've written about hyperthyroidism.

Dr. Mark E. Peterson said...

Here's a link to all of the other posts I've written about hyperthyroidism.

Mishal said...

Hello. I just found this article through google. I have a 1-year old mixed breed cat. He is very active still, and strangely no longer is tolerant of being held and gets very very squirmy. I can't tell if his activity is coming from growing out of being a kitten or hyperthyrodism. He's so young though, but his history is pretty unknown.

He is a not-quite long-haired black cat who has recently started panting almost all the time, ordinarily I would think it's just the summer, but despite him staying around my other cats, none of them are panting. H is also starting to not be as focused on grooming as before and is developing oily patches where he isn't grooming above his tail. His defecations seem normal, but he is urinating a lot, but the color is normal and he doesn't seem to be drinking to excess. His hair also starting to turn reddish-brown, except for in a very obvious pattern from his head to a triangle right between his shoulder blades.

Are those symptoms of hyperthyroidism in a young cat?

Dr. Mark E. Peterson said...

Bottom line: young cats don't develop hyperthyroidism. Only 5% of cats with the disease are less than 10 yrs, and almost none are less than 7-8 years.

Diana Dimova said...

Hello. I found this page by chance but I am happy I did. I am a foreigner and my English is not very good so I do appologize.My cat is a rescue and I am not sure what exactly his age is but it is something like 8 years old. He was diagnosed with diabetes 2 months ago and is on Insulin twice a day but till now we cannot regulate him. Lately he developed strange cough, has rapid breathing and doesn't gain any weight though he eats the normal dose of wet low carb food for diabetic cats.Severe hunger drives him crazy but I have to give him only the prescribed dose per day.Definitely he has many of the symptoms described and I am planning a T4 test My question is can possible hyperthuroidic condition be a problem for regulating my cat and will this problem be solved once we start treatment providing diagnosis is confirmed of course. Thank you !

Dr. Mark E. Peterson said...

Your vet should run a serum T4 level to rule out hyperthyroidism. See my many other posts that discuss treatment of this condition.

Dr. Mark E. Peterson said...

I'm sorry, I meant DIAGNOSIS of hyperthyroidism, not Treatment. Before we treat, we must first make sure that your cat is even hyperthyroid.

Diana Dimova said...

My cat will certainly have the test done though laboratories here perform a test which is not exactly T4 but FT4 and it is in human not vet laboratories. I was just curious if this condition can be a problem for the regulation of diabetes. Thank you for your comment and advice Dr. Peterson.

Dr. Mark E. Peterson said...

Hyperthyroidism can make the regulation of diabetes more difficult, but many diabetic cats are difficult to control and very few are hyperthyroid.

Your vet should also be looking for other problems/issues in your cat. This topic is way too much for me to cover here - there are a multitude of book chapter and research papers devoted to the difficult-to-manage diabetic cat.

Diana Dimova said...

The problem Dr.Peterson is that the vet specialists in my country don't have much experience with diabetes as most people whose pets are diagnosed don't bother to even try with treatment.It is costly which they cannot afford and involves very serious personal commitment as well.This is why I have read quite a lot on Internet including the FDMB. It is indeed difficult to regulate my cat but he has problem that additionally makes things even worse. I suspected hyperthyroidism as Misho had all symptoms described. T4 test at least will make things clearer. If it is not the condition he has I wonder what this problem might be.Thank you for your directions!

Diana Dimova said...

Dear Dr.Peterson, my cat had his FT4 and TSH tests done .Results are FT4 - 24,60pmol/l and TSH 0,08mlU/l .Can you please tell me if these levels are something to worry about.Thank you!

Dr. Mark E. Peterson said...

Sounds like both tests are normal to me. Ask your vet to confirm that the levels are within reference range limits.

kathy said...

My cat had the i131 treatment June 18th and was sent home the morning of June 22nd. She has recently been throwing up hairballs every couple of days. She has only puked food once in the morning since the treatment (which is a big change) and it was lll of the food she ate. I think she just ate too fast.
My question is, is it normal for a cat to have increased hairballs after treatment? Is this something people say they notice in their cats?

Dr. Mark E. Peterson said...

We don't typically see excessive shedding immediately after treatment. Cats that develop hypothyroidism will shed excessively, but that doesn't usually develop this soon.

Talk to your vet about repeating the thyroid and other blood tests looking for nonthyroidal issues.

Anyway, it's not from the I-131 treatment itself.

Asya Ludmilova said...

Dear dr.Peterson
Although not answered my last post, I want to tell you that I am very grateful for the invaluable information you have provided to all of us who want to help their favorite cats.
Eventually my so beloved Mimi / cat / sugar proved non-diabetic renal glyukozoriya.
I would love to of functionality I had to express my gratitude and podrug way than by words.
Here in Bulgaria, doctors believe that treatment with mineral radon / R222 / water contributed to the recovery of thyroid gland.
No if it's true I do not know.

I wish you health and luck!

nala wall said...

Dr. Peterson,
My cat is showing symptoms of what I think could be hyperthyroidism (weight loss, panting, vomiting) but from what I understand this is a disease which mostly affects older cats. My Oscar is only 2 years old. I've been searching for an "online diagnosis" since I don't have much access to veterinary care and have come up with some very troubling possibilities. I'm very worried. Can you help?

Dr. Mark E. Peterson said...

To confirm hyperthyroidism, you need to show that your cat's serum T4 value is high. So no, I cannot diagnose hyperthyroidism based on history alone.

Keith Hallam said...

My 15 yr old cat was diagnosed with hyperthyroidism yesterday and started meds right away. It seems we may have missed the signs over the past couple of months if excessive meowing and hunger- he's always been both so it didn't reLly send major flags. However in the past week he has list alit if weight and started to become lethargic so we took him to the vet. Last night was his first pill and we noticed an increase to his activity but decrease in appetite. Sunday he ate his normal can of food but ninday only about half a can and today barely 1/4 can. He has become increasingly confused and weak but just paces around then falls due to weakness.
We know he is old and he seems so fragile right now we just don't know if we need to give more time for the meds to work or if he is suffering and we need to put him down. So sad and confused...

Dr. Mark E. Peterson said...

This could be a reaction to the medication. You can read my other blog posts in which I discuss the methimazole and its side effects.

Talk to your vet about this issue.

Think again said...

Hi, my kitten has quite a few of these symptoms. Is it possible for her to have been born with it or for her to develop this at such an early age? She has been to the vet numerous times and we can't find out what is wrong with her.

Dr. Mark E. Peterson said...

Juvenile hyperthyroidism is extremely rare. If your vet feels that it is possible, they should measure a thyroid level (T4) to see if it is elevated. If it's not, then your kitten is not hyperthyroid.

Cindy said...

My cat, even though still very young (2 1/2 yr old) is showing all but one sign listed here... What kind of test should I request the vet to see if he has hyperthyroidism?

Dr. Mark E. Peterson said...

Serum T4 determination - diagnosis is all detailed in my other blog posts.

Dorothy Griffith said...

Hi Dr Peterson

My cat, Pitune just put her down last Sunday. She was 17.5 years old, had methimazole 5 mg medication twice daily. I decided to give her only once every morning because her body was shaking ans twist her face.

Her behavior became abnormal due to walking slow, slept under the hope chest and ate alot the food and drank more water since I adopted her in 2011 when her owner had passed away.

Pitune was my best friend almost 4 years. I sometime think about the medication of methimazole cause elderly cats became more weaker and shake / twist face.

The vets said, if we do her blood work with kidney/ liver which was not worth. Doctor notice, Pitue's behavior change due to her head was turn around while she walked and slept alot. We were worried if she would die at home with other three cats.

It was very difficult for us to made the decision to put her down within 2 hours because we love Pitune very much.

I miss her. :-(


Dr. Mark E. Peterson said...

Dear Dottie,

I'm so sorry to hear about your loss of Pitune. My condolences.

Dr. Peterson

Wilbur said...

Hi Dr Peterson,

Thanks so much for this article.

My cat, Wilbur, is 9 and at stage 4 renal failure. Even though he is on a regime of subq's, b vitamins, cerenia/prilosec/zantac and bp meds, he lays in the closet all day sleeping and won't eat. He's lost 1lb in just a week and trying appetite stimulants hasn't helped.

When I read about apathetic hyperthyroidism and am curious if this could be what's happening. Would I feel an enlarged thyroid at the base of the neck? (I have hashimoto's so I'm aware of feeling my own thyroid)

I don't recall his thyroid being tested recently and we just had bloodwork yesterday. Is it possible to test from that sample? If so, what tests should I request?

Thanks so much!


Dr. Mark E. Peterson said...

Stage 4 kidney failure certainly could make a hyperthyroid cat apathetic. That said, it would be unlikely that a 9 year old cat is hyperthyroid (too young - almost all cats are older tha 10 years).

You would not be able to palpate the thyroid but your vet probably could (if present). Running a serum T4 would rule out hyperthyroidism. I would expect the T4 to be low, not high, because other illness lowers the T4 concentration.

Unfortunately, even if hyperthyroidism was present, it would not help your cat's prognosis due to the the severity of kidney disease. No matter how you cut it, the kidney disease is the main problem.

lisa evans said...

Hi Dr Peterson
Please please help!
I have a 9 year old cat who for the last 2 years has become listless, disinterested in everything, put weight on and even more in the last 4 weeks, and has become bald all over his belly, front legs and on the inside and outside of his hind legs, he sleeps all the time and when hes not sleeping he grooms himself excessively. At his last check up in june we were advised to cut his food intake which we did. He now has half a sachet of wet food and about 100g of james wellbeloved divided into a morning and evening portion. He has no titbits or treats as he was diagnosed with ibs about 3 years ago and as a result can cause diarrhoea. He has put a lot of weight on over the last month and now im getting worried.
Our vet said he had ocd and anxiety but im wondering if it could be hypothyroidism as a pose to hyperthyroidism. Could a blood test for T3 and T4 be helpful.I would appreciate any advice.
many thanks

Dr. Mark E. Peterson said...

It's unlikely that the thyroid is the problem here, but running a serum T4 is never a bad idea, especially in a 9-year old cat. Either hyper- or hypothyroidism could cause hair loss. Weight gain would be more common with hypothyroidism.

J Jones said...

My 12 y/o cat Baby Girl has steadily lost weight over the last 4 years. I didn't notice it at first (she was a bit on the heavy side), but she has almost lost half of her mass. She has shown many of the symptoms you mentioned, but every time she gets a blood panel and a T4 test, the results come back as normal. The vet has put her on steriods to get her appetite back up, but she quickly reverts back after she's done.

I have read elsewhere that some cats who have hyperthyroidism and show 'normal' T4 levels when tested. I'm wondering if this may be her case. I'm getting a bit concerned as she's been untreated for so long. I'm wondering what might I expect if she does start treatment so I can be prepared.

Thank you for posting this.

Dr. Mark E. Peterson said...

About 95% of hyperthyroid cats will have a high serum T4, whereas 98% will have a high free T4. Both of these tests are available for your vet to use.

Hyperthyroid cats lose weight DESPITE an increase in the cat's appetite. They do not need steroid injections to make them eat.

Your vet needs to figure out what's wrong. If they don't know, they should offer you a referral to an internal medicine specialist.

Worried Mom said...

My 4yr large cat was 13.4 pds on 6-13 when he went for his annual exam and vaccines. Told vet about an increase in appetite and thirst. She did blood work and also gave FVRCP and Rabies vaccine. Blood was very good exception of Platelets high. T4 2.3 (greyzone)but he is young so felt it was not Hyperthr.
Three weeks later he weighed 10.9lbs with 103.5 fever. Was vomiting and diarrhea. Upon exam Dr. felt a mass in stomach that was not felt by Vet at checkup, sent to internal specialist who did a Ultrasound and aspiration. No cancer in biopsy so treated with antibiotics for infection. Got better after meds. Now in October he has ALL the signs of Hyperthyroid. Increase appetite and thirst, but very skinny, EXCESSIVE grooming to the point of raw, nervous, occasionally peeing and pooping outside box and generally not looking comfortable. Took to Vet. No fever and weighs 12.2lbs and they still feel a mass in tummy so they suggested changing to Hill ZD for possible allergy and gave me metoclopramide syrup and catlax to see if we could move the mass. Should I insist on another Thyroid test? Could the FVCP vaccine have cause this? He is indoor cat but will run out on the sidewalk and lick the cement?? I know something is wrong with my cat but I don't know what to do. Any suggestions?

Dr. Mark E. Peterson said...

Fever, masses in the abdomen, etc are not part of hyperthyroidism. I'd get a referral to an internal medicine specialist.

Demi D said...

hi dr.peterson
my 7 months old kitten have a massive weight loss and all of the signs in your post . for at least 4 months now . two weeks ago some swelling and blood appears on her left eye now the blood almost gone she can open her eye but the eyeball still bigger than the other and i think she can't see clear in that eye. could she have hyperthyroidism of this age ? i don't have an advanced pet clinic where i live or a REAL vet so i like to know if it possible to have it in this age before i go and ask for the test !
thank you .
p.s * every time i went to a vet he gives me a dewormer and it doesn't work !

Dr. Mark E. Peterson said...

7-month old cats do not develop hyperthyroidism, nor do they develop swelling of the eye(s). Talk to your vet (or find another one if you aren't happy with your current vet).

Lou said...

My 13 y/o cat, Spot, was recently diagnosed with hyperthyroidism. He was on Methimazole 5 mg once daily in the evening. The Methimazole brought his T4 level to within normal limits, but we had to discontinue it due to side effect (loss of hair and skin ulcerations). Since discontinuing the Methimazole, his fur is back to normal and the ulcerations have healed. He is currently on Y/D, which has helped with his loose stools. However, he still cannot hit the litter box. Also, after starting the Y/D, he has what I call "food balls", regurgitated food mixed with a hairball. The food balls are becoming more frequent, especially after he gorges himself with food.

After reading your literature online, I think he will respond well to the I-131 therapy. Do you know of a facility in Maryland, that does the radioisotope therapy, as Spot does not travel well? I live about 2 hours south of Baltimore, so Annapolis would be a good distance for him. Thanks!!!!!!!1

Dr. Mark E. Peterson said...

I cannot recommend any specific facility but I'm certain that there are many sites close to where you are located. Do a search online or talk to your vet.

Gail R Berger said...

We have a 18 1/2 year old, who has been diagnosed with hyperthyroidism with mixed signs. Last year she weighed 9.5 lbs. Now she weighs 9.0 lbs. Her appetite has increased somewhat. She eats around every 2-3 hours around 2-3 teaspoons at each meal. Her coat looks good. She still has a stomach pouch, though she has lost weight on her back. She has been holding her food down. Her activity level is about the same. We brought her to the vet Friday. Her heart rate was 160 beats. Her respiration after calming down (she hates going to the vet) was normal. Her doctor at first felt her thyroid gland and did not feel anything and then with second exam felt a tiny slip on the left side. We drew blood. Within 24 hours the lab results showed T4 readings "2-3 times normal." Vet wants to start tapazole at 2.5 mg and go up to 5.0. Her kidney functions were normal. I would prefer to watch her response to the 2.5 mg and then move up to the higher amounts as needed. Especially if there is any hidden CKD that the treated hyperthyroid condition would reveal, I would like to proceed conservatively in light of the mixed clinical symptoms. What do you think?

Dr. Mark E. Peterson said...

I agree. Have you read all of my other posts about methimazole treatment?

Asya Ludmilova said...

Hello Dr. Peterson
Again I write you, Asya from Bulgaria. Нope very much to help me with, your professional opinion.
Recently I wrote about my cat with hyperthyroidism.
For three months after the diagnosis we had to adjust the dose of metizol until we came to 2.5 mg. / 12 hours. Luckily she did not show kidney problems. Accompanying disease due to hyperthyroidism in it is cardiomegaly.
For two months, it was treated with this dose of metizol. Started and visible positive changes as weight gain, bed-hair, less water, no heat intolerance and many others ..
Yesterday, however, did blood tests planned, and now here comes the big surprise !!!
Perfect blood have a look, all indicators the norm just perfect, perfect urine tests.
But FT4 index with 8 pmol / l.At lower limit 10 pmol. / L we were clearly hypothyroid.
Please share with me your experience. See is that it is hypo-limit but it has perfect performance, feels good and has no clinical symptom of hypo.
What would you advise me to do.
To decrease my dose metizol given that we have such perfect blood results, and I have no negative behavior and signs of the cat?
Is it possible transit hyperthyroidism?

Thank you very much
I appreciate all your advice.

Dr. Mark E. Peterson said...

Have you read my other posts about monitoring on methimazole? We generally use total T4 to monitor, not free T4. So if the total T4 was normal, I would ignore the FT4 result. Most methods for free T4 are not very accurate and commonly give falsely low or high results.

Talk to your vet about all of this.