Documentary of Pet Food Industry — "Pet Food: A Dog's Breakfast"

We love our pets, but do we really know what we're feeding them? My last post discussed how to better interpret a pet food label.

Now, if you haven't already seen it, I've included a link to a must-see documentary about the pet food industry entitled, Pet Food: A Dog’s Breakfast (1).  But be warned— this film is almost 45 minutes long.

This film takes the lid off the can to discover what’s going on inside the $16 billion pet food industry. The program, produced by Yap Films, an independently owned production company (2), was originally televised by the Canadian Broadcasting Corporation in August of 2009. Its production was sparked by the 2007 pet food recall in which tens of thousands of cats and dogs in North America became sick after being fed tainted pet food.

The film supposedly had been scheduled to air on CNBC earlier this year but was canceled without explanation. But now, interestingly, it has resurfaced on YouTube for all of us to see.

So when you see the ads about pet food, claiming that the food is "healthy, has all the essential nutrients, and is best for your pet" we should stop and wonder — is all that marketing really true? This documentary uncovers part of the truth. Yet there is much more to learn. After watching this documentary, however, your eyes should open up and you may no longer blindly trust the commercial pet food companies. I no longer do.

But what to feed? Home-made, raw? I certainly don't have all the answers. But if you have the time, home-prepared diets may offer the best means to feed your pet a healthy whole food diet (3-5).

Links:

1. YouTube. Pet Food: A Dog's Breakfast  
2. Yapfilms.com 
3. Strombeck's Home-Prepared Diets For Dogs and Cats: Safe, Balanced, Complete & Up-to-Date.  Dogcathomeprepareddeit.com. 
4. Schenck P. Home-Prepared Dog & Cat Diets. Second Edition, Wiley-Blackwell, 2010.
5. Pierson LA. Making cat food.  Catinfo.org.  

Pet Food Labels: Reading Between the Lines

We can all be passionate about choosing the best food for our dogs and cats. With thousands of pet food products on the market, how do pet owners make the best choice?

Pet food labels are a good place to start. Understanding the label information can help us make informed decisions about the food we feed their pets. Knowing how to read a pet food label can help answer questions, serve our pets’ nutritional needs, and optimize patient care.

This easy-to-read article addresses how to read a pet food label discusses the key issues you should be familiar with before you go shopping for pet food in order to make the best choice for your dog or cat.

• Smith JM. Pet food labels: Reading between the lines. Veterinary Technician. September 2011; Volume 32, Number 9. Online at www.vetlearn.com. 

Dangers of Holiday Snacking for Your Diabetic Dog or Cat

During the winter holidays, the average person tends to gain weight because of the parties and snacking on delicious goodies. Our dogs and cats are keen to these festivities.

Our pets are often times smarter than we are when it comes to food. An otherwise normal pet can become a diabolical genius when it comes to begging. Your pet's pleading warm brown eyes that seem to penetrate to your very soul and can sway your better judgment. But what may be a "little bite" to someone the size of a human is much more to a small dog or cat!

More of a Problem in the Diabetic Dog or Cat

Although feeding treats to a normal dogs and cats may just lead to weight gain, the issue is much more important in your diabetic pet.

Dogs tend to be keenly aware of all the goodies and baked goods in the home. All the sugar in such special holiday treats can be very detrimental to diabetic control. Giving a high-sugar treat in the middle of the day is likely to cause an unwelcome glucose spike.  If you must give in, choose a low-sugar healthy snack and give it with the dog's meal. Of course, if you are giving a treat, cut back appropriately on the amount of regular food given to your dog.

These snacking situations may be less troubling for cats. Cats are usually drawn toward the ham and turkey and not so much the sweets and breads we find in our homes over the holidays. Cats do not have the taste receptors for sweetness so they cannot taste sugars (1-3). Cats tend to be nibblers and are often placed on a longer-acting insulin. A nibble here and there of a low carb bit of meat isn't typically a problem for your diabetic cat.

Chocolate is Toxic

Make sure that any holiday chocolates are kept away from where your pet can reach them.  Even small amounts of chocolate can result in poisoning in dogs and cats (4).

The toxic principles in chocolate are the methylxanthines, theobromine and caffeine. Although the concentration of theobromine in chocolate is 3-10 times that of caffeine, both constituents contribute to the clinical syndrome seen in chocolate toxicosis.  Listed below are the total methylxanthine concentration of commonly used chocolate products:

• Dry cocoa powder ~800 mg/oz (28.5 mg/g)
• Unsweetened (baker’s) chocolate ~450 mg/oz (16 mg/g)
• Semisweet chocolate and sweet dark chocolate ~150-160 mg/oz (5.4-5.7 mg/g),
• Milk chocolate ~64 mg/oz (2.3 mg/g)
• White chocolate is an insignificant source of methylxanthines.

Serious poisoning happens frequently in dogs and cats who metabolize methylxanthines much more slowly than human; they can easily consume enough chocolate to be poisoned (5-6).

The most common victims of theobromine poisoning are dogs, for which it can be fatal. The toxic dose for cats is even lower than for dogs. Again, cats are less prone to eating chocolate since they are unable to taste sweetness (1-3).

In general, mild signs (vomiting, diarrhea, polydipsia) may be seen in dogs ingesting 10-20 mg/kg, cardiotoxic effects may be seen at 40-50 mg/kg, and seizures may occur at doses ≥60 mg/kg (5-7). One ounce of milk chocolate per pound of body weight is a potentially lethal dose in dogs.

A typical 20 kg (44 lb) dog will normally experience intestinal distress after eating less than 240 g (8.5 oz) of dark chocolate, but won't necessarily experience toxicity unless it eats at least half a kilogram (1.1 lb) of milk chocolate. Large breeds (>100 lbs) can safely consume chocolate in limited quantities, but care must still be taken, as they can safely eat only about a quarter the amount a human can, and should not be intentionally fed it.

References:

1. Li X,  Wang H, Cao J, et al. Pseudogenization of a sweet-receptor gene accounts for cats' indifference toward sugar. PLoS Genetics 2005;1:27-35. 
2. Li X, Li W, Wang H, et al. Cats lack a sweet taste receptor. Journal of Nutition 2006;136:1932S-1934S. 
3. Biello, David (August 16, 2007). Strange but True: Cats Cannot Taste Sweets. Scientific American. Retrieved July 28, 2009.
4. Smit HJ. Theobromine and the pharmacology of cocoa. Handbook of experimental pharmacology 2011;(200):201-234.  
5. Stidworthy MF, Bleakley JS, Cheeseman MT, et al. Chocolate poisoning in dogs. Veterinary Record 1997;141:28. http://www.ncbi.nlm.nih.gov/pubmed/9248028 
6. Gunning ME, den Hertog E, van Velsen NF, et al. Chocolate intoxication in dogs. Tijdschrift voor Diergeneeskunde. 2010;135:896-899. 
7. The Merck Veterinary Manual (online edition). Chocolate. www.merckvetmanual.com 

Sugar: The Bitter Truth by Robert Lustig, MD

In my last post, I reviewed the book by Gary Taubes, entitled Good Calories, Bad Calories: Challenging the Conventional Wisdom on Diet, Weight Control, and Disease.  In that book, Taubes convincingly states that the problem with our diets lies in refined carbohydrates and sugars. He states that refined carbohydrates do harm via their dramatic and long-term effects on insulin, the hormone that regulates fat accumulation, and that the key to good health is the kind of calories we take in, not the number. There are good calories, and bad ones.

Robert H. Lustig, MD, Professor of Pediatrics in the Division of Endocrinology, University of California San Francisco has published and lectured extensively on the damage caused by sugary foods, especially the sugar fructose (1-8). He argues that ingestion of too much fructose and and not enough fiber appear to be cornerstones of the obesity epidemic in the US and result of the developed countries through their effects on insulin.

On May 26, 2009, Dr. Lustig gave a lecture called “Sugar: The Bitter Truth” which was posted on YouTube the following July and has become a viral success with over a million viewings. In this lecture, Lustig notably calls fructose a "poison" and compares its metabolic effects with those of ethanol. This lecture is a excellent and through review of this topic, but be warned — this is an hour and a half lecture! But I think that you will find it worth your time— it may change the way you life and eat.

• Sugar: The Bitter Truth 

In the second lecture presentation, Dr. Lustig, discusses "sugar addition" and explores methods we can all use to reduce sugar consumption.

• Interventions to Reduce Sugar Consumption 

References: 
Dr. Lustig's Papers on Fructose 

1. Lustig RH, Sen S, Soberman JE, et al. Obesity, leptin resistance, and the effects of insulin reduction. International Journal of Obesity and Related Metabolic Disorders 2004;28:1344-1348. 
2. Lustig RH. Which comes first? The obesity or the insulin? The behavior or the biochemistry? The Journal of Pediatrics 2008;152:601-602. 
3. Johnson RK, Appel LJ, Brands M, et al. Dietary sugars intake and cardiovascular health: a scientific statement from the American Heart Association. Circulation 2009;120:1011-1020. 
4. Lustig RH. The fructose epidemic. The Bariatrician 2009:10-18. 
5. Lim JS, Mietus-Snyder M, Valente A, et al. The role of fructose in the pathogenesis of NAFLD and the metabolic syndrome. Nature Reviews Gastroenterology & Hepatology 2010;7:251-264. 
6. Lustig RH. Fructose: metabolic, hedonic, and societal parallels with ethanol. Journal of the American Dietetic Association 2010;110:1307-1321. 
7. Nguyen S, Lustig RH. Just a spoonful of sugar helps the blood pressure go up. Expert Review of Cardiovascular Therapy 2010;8:1497-1499. 
8. Garber AK, Lustig RH. Is fast food addictive? Current Drug Abuse Reviews 2011;4:146-162.

How Do Dietary Sugars Relate to Animal Nutrition?
Over the past five years, sugar has increasingly been added to some popular brands of dog and cat treats to make them more palatable and profitable (1-3). Like people, these sugars are not needed for our dogs or cats and are best avoided (4). These sugary treats are likely contributing to the rapid rise in obesity in our pets.

Sugar is also added to pet foods and treats for a variety of reasons, other than those are related to palatability. For example, corn syrup is used as a thickener and to suspend the dough for proper mixing of ingredients, and dextrose is used to evenly distribute moisture throughout a food (1). Sugar has a role in the physical and taste characteristics of many products, helping to mask bitter flavors imparted by acidifying agents, or changing the texture of specific treat types.

Dr. Lustig's work also emphasizes the importance of nutrition as part of treatment of all medical disease (see above). His work in this field has been both compelling and eye-opening, and I am now thinking more critically about the unnecessarily high sugar content in pet food treats and some pet foods. Remember that dogs, like humans, are omnivores and both species handle carbohydrates in much the same manner. Cats, on the other hand, are obligate carnivores, so sugars should never be included in their diet, if possible (5).

Animal References:

1. Healthday, December 08, 2010. Those Sweet Pet Treats May Foster Fatness: Sugar appearing more now in dog and cat treats as veterinarian warns of the consequences.  
2. Press Release, Association for Pet Obesity Prevention (www.petobesityprevention.com), June 17, 2010. Kibble Crack – Vet Exposes Sugary Secret of Pet Treats. Sugar is being added to many pet treats contributing to the growing pet obesity epidemic. 
3.  Petfood Industry (www.petfoodindusty.com), December 13, 2010. Sugar in pet treats may be contributing to obesity.  
4. The Dog Food Project (www.dogfoodproject.com). Ingredients to avoid.
5. Kienzle, E. Blood sugar levels and renal sugar excretion after the intake of high carbohydrate diets in cats. The Journal of Nutrition 1994; 124:2563S-2567S.

Book Review: Good Calories, Bad Calories

For decades we have been taught that fat is bad for us, carbohydrates better, and that the key to a healthy weight is eating less and exercising more. Yet with more and more people acting on this advice, we have seen unprecedented epidemics of obesity and diabetes.

Gary Taubes, a correspondent for Science magazine, contributed to the Atkins Diet craze with his New York Times article several years ago, "What If It’s All Been a Big Fat Lie?." He then spent the past several years expanding on that article, and the result is Good Calories, Bad Calories: Challenging the Conventional Wisdom on Diet, Weight Control, and Disease, a book of some 600 pages (nearly 70 of which make an extensive list of references).

In this book, Good Calories, Bad Calories: Challenging the Conventional Wisdom on Diet, Weight Control, and Disease, Taubes argues persuasively that the problem lies in refined carbohydrates (e.g., white flour, sugar, easily digested starches) and sugars. He states that refined carbohydrates do harm via their dramatic and long-term effects on insulin, the hormone that regulates fat accumulation, and that the key to good health is the kind of calories we take in, not the number. There are good calories, and bad ones.

Good Calories
These are from foods without easily digestible carbohydrates and sugars. Examples in include meat, fish, fowl, cheese, eggs, butter, and non-starchy vegetables. Taubes claims that these foods can be eaten without restraint.

Bad Calories
These are from foods that stimulate excessive insulin secretion and so make us fat and increase our risk of chronic disease—all refined and easily digestible carbohydrates and sugars. The key is not how much vitamins and minerals they contain, but how quickly they are digested. Therefore, apple juice or even green vegetable juices are not necessarily any healthier than soda.

Examples of "bad calories" according to Taub include bread and other baked goods, potatoes, yams, rice, pasta, cereal grains, corn, sugar (sucrose and high fructose corn syrup), ice cream, candy, soft drinks, fruit juices, bananas and other tropical fruits, and beer.

Major Critical Points of Good Calories, Bad Calories
Taubes has several overarching themes. He contends, for example, that eating refined carbohydrates is what makes you obese, and that refined carbohydrates contribute to many of what used to be called "diseases of civilization" such as heart disease, which seems to have been less common in traditional cultures that ate less processed food, including Northern cultures that ate almost exclusively meat. (These arguments are still controversial, although new evidence continues to support them.)

With precise references to the most significant existing clinical studies, he convinces us that there is no compelling scientific evidence demonstrating that saturated fat and cholesterol cause heart disease, that salt causes high blood pressure, and that fiber is a necessary part of a healthy diet. Based on the evidence that does exist, he leads us to conclude that the only healthy way to lose weight and remain lean is to eat fewer carbohydrates or to change the type of the carbohydrates we do eat, and, for some of us, perhaps to eat virtually none at all.

Overall, this groundbreaking book, the result of seven years of research in every science connected with the impact of nutrition on health, award-winning science writer Gary Taubes shows us that almost everything we believe about the nature of a healthy diet may be wrong.

How Does This Book Relate to Animal Endocrinology?
It is obvious that many aspects of nutritional biochemistry and metabolism involve endocrinology and metabolism (regulation of insulin secretion and fat production). Remember that we as humans are also animals, and as omnivores, our nutritional needs are fairly close to dogs and other omnivores. Cats, on the other hand, are obligate carnivores, so their nutritional needs are quite different (i.e., high protein requirements but no need for carbohydrates at all).

This book also emphasizes the importance of nutrition as part of treatment of all endocrine disease, as well as all medical disease in general. The nutritional content of food has been something I have been focusing on recently, both for myself personally and also as a veterinary endocrinologist interested in furthering my understanding of animal health and medicine. Taubes' work in this field has been both compelling and eye-opening, and I am now thinking more critically about the unnecessarily high carbohydrate content of pet food (especially for the carnivorous cat).

Overheard on the Web: Hypurrcat Recommended on the Feline Hyper-T Yahoo Group

Below is a post we found on the Hyperthyroid Cat Yahoo Group, which is the original support list for people whose cats have been diagnosed as hyperthyroid or hypothyroid. Founded in 1999, the group has over 2400 members.

This is a great resource for anyone whose cat has been diagnosed with hyperthyroidism or hypothyroidism. The group is full of caring and supportive people who are more than willing to share their experience.

I-131 In NYC?

I joined the group about two weeks ago after we got a hyperthyroid diagnosis for my 14-year old kitty. She's started the methimazole, which seems to be going well. She's hard to give pills to, and HATES having her ears messed with, so we opted to try the chicken flavor "chewies" — which she scarfs right down. What a relief!

Now we're starting to think about the I-131 procedure. Our vet said they have a few places that they can recommend, and we'll get more details from them when we go back for the first checkup in a week or two, but thought we might start doing research now. We live in NYC, so that would be best for us.

I know Dr. Peterson has a clinic in Manhattan and is highly thought of on this group, and we'll definitely be looking into that option. But I was hoping there are others on the list who might offer their experiences with any places in NYC.

Sampson Thunderpaws, a 12-year, male Maine Coon cat treated at Hypurrcat

Response: I-131 In NYC?


Sampson Thunderpaws went to Dr. Peterson's clinic in Bedford Hills, NY about 3 weeks ago. If the clinic in Manhattan is anything like the one in Bedford Hills, Suki will be thoroughly spoiled by the time she gets home.

• Dr. Peterson tailors each I-131 dosage to the cat and his/her needs rather than give a set dosage per cat as some of the clinics do. 
• There is a vet tech in with the cats all day, and I caught her feeding Sampson (there are webcams in every "condo") after 8 pm one night. 
• They answered all my emails promptly — and I sent a "few". :) Sampson was hand-fed when he didn't want to eat and they gave him additional cooked pieces of chicken to tempt him.
• They have lots of things for the cats to watch — cat TV and real, live Gerbils in cages just outside their "condos".
• Oh — and they brought him a gerbil in a ball to keep his hunting skills sharp. LOL! (A vet tech was there every minute so no gerbils were harmed in the process.)

Dr. Peterson is the man for hyperthyroidism with 30-plus years experience, so that is the real reason we went there—but I couldn't have asked for a better experience for Sampson. Which made it easier for me to leave him there.

 Peace, Plenty and Purrs,
Memory and Sampson Thunderpaws

Sampson Thunderpaws, a hyperthyroid cat treated at Hypurrcat

Rosie, the Bodega Cat: Epilogue #2

Hi there,

"Rosie" here again... it's been awhile since I last wrote to you... see my previous posts here to get my background.

• November 2, 2011: The Story of Rosie, the Hyperthyroid Bodega Cat
• November 7, 2011: Rosie, the Hyperthyroid Bodega Cat: an Epilogue

This must be heaven — Cat Heaven, that is!

My new home is beautiful and comfortable beyond my wildest dreams. Yes, I often dreamed of going back to a beautiful apartment again, but this place is absolutely divine, or, as they say: it's the cat's meow! Unbelievable!

Now I have two beds. One is in the living room den area, and one in Gladys' bedroom. I have breathtaking views of the city from a very high, unobstructed viewpoint. I also have lots of toys, and a shiny new feeder and water bowl. There's lots of windows, and a balcony with a bird feeder. So I'm having fun watching the birds again, just like I did during my stay at the Hypurrcat treatment facility at at the Animal Endocrine Clinic to get my hyperthyroidism cured!

This is all very hard to believe —maybe I have died and gone to Cat Heaven! Pinch me, please! But I'm here, and I love it. And Gladys is very happy to have me here, and in her life.

Sometimes I miss my old life at the bodega, but that feeling doesn't last long! Why should it? I'm now "Rosie, the Celebrity Penthouse Queen Cat"!

That's a long title for a little 9-pound "Rosie," but it's true, and I love it! Gladys and I are going to be so happy together.  It's like a fairytale dream come true, and little "Rosie" is the main character in this dream life I'm leading now. I hope you enjoyed hearing about this new and exciting change for "Rosie" and Gladys!

That ends my "Rosie" story for now, because I'm going to be really happy and content in my new home for the rest of my life. Wouldn't you be?

Life is good... And I feel much better now that my hyperthyroidism has been cured!

XOXO
Rosie

Dr. Peterson Interviewed about Hyperthyroidism on PetLifeRadio

PetLifeRadio.com is the #1 pet podcast radio network, featuring weekly 30-minute talk shows hosted by the most well-known pet experts.


On Wednesday, November 10, 2011, Dr. Mark Peterson was interviewed by the Pet Doctor (Diane Levitan, DVM) concerning the latest information about hyperthyroidism in cats. To listen to this interview, click on this link to go to "The Pet Doctor" page on PetLifeRadio.com.

Episode 129:  

Hyperthyroidism In Cats—A Very Common Problem with Many Options—A Must Listen Show for Anyone with Cats Over 9 Years of Age 

Excerpt:
In this episode, we discuss a very common problem that happens in older cats — it’s a disease that has become much more common since the 1980s and is something that has been a difficult one to figure out. There turns out to be a good reason why older cats eat like crazy but still become very thin, they drink tons of water all the time, and their hyperactive behavior keeps their owners up at night! 

It is very likely that the symptoms are due to an over-active thyroid gland, also called hyperthyroidism. There is a great deal of information on feline hyperthyroidism that has been learned in the last 20 years—what is it from? Why is it so common? What are the long-term effects on our cats and how can we prevent it? 

Today we are extremely privileged to have Dr. Mark Peterson, a veterinary endocrinologist and the first in the world to publish information on this ever so common illness in cats, hyperthyroidism. He is known worldwide for his research and contributions to veterinary medicine and veterinary endocrinology and is the go to person in the world when it comes to feline hyperthyroidism and many other veterinary endocrinology topics. 

Learn more about Dr. Peterson by listening and also check out his web site: www.animalendocrine.com.

Click here to listen to the interview or download it to your computer. This is a 30-minute interview. Information on nutritional management using Hill's y/d diet is discussed in the last 5 minutes.

World Diabetes Day

Today, November 14th, is World Diabetes Day

World Diabetes Day is the primary global awareness campaign of the diabetes mellitus world and is held on November 14 of each year (1). It was introduced in 1991 by the International Diabetes Federation and the World Health Organization in response to the alarming rise of human diabetes around the world. 

World Diabetes Day is a campaign that features a new theme chosen by the International Diabetes Federation each year to address issues facing the global diabetes community. While the campaigns last the whole year, the day itself marks the birthday of Frederick Banting who, along with Charles Best, first conceived the idea which led to the discovery of insulin in 1922 (2).

Charles H. Best and Frederick G. Banting (on right) with one of the diabetic dogs used in their studies of insulin

This year's campaign theme is diabetes education and prevention. In the past four years alone, diabetes rates among dogs in the U.S. have increased roughly 33% among dogs and 16% among the nation's cat population, per a national analysis of pet health (3).  This emphasizes the importance of this disorder in our cats and dogs as well as human patients with diabetes.

To successfully manage diabetes in animals, one must understand the disease and monitor and provide daily treatments to the cat or dog with diabetes. Treatment involves a combination of weight loss (if obese), diet, and insulin injections generally twice daily.

References 

1. World Diabetes Day – Official website.
2. Frederick Grant Banting (1891-1941), codiscoverer of insulin. Journal of the American Medical Association 1966;198:660-661.
3. Washburn L. Human health risks on the rise in animals. The Record. April 20, 2011.

Update on the Perilous Situation of Dogs & Cat Exposed to Radiation Fallout from the Fukushima Nuclear Disaster

Thousands of dogs and cats were abandoned after an earthquake damaged Japan's Fukushima nuclear plant, and continued radiation concerns have stymied recovery efforts.

Although the radioactive material the dogs and cats were exposed to during the disaster should be cleared by the their bodies by now, the animals may have incurred permanent damage according to Timothy Mousseau, a professor of biological sciences at the University of South Carolina, who has extensively studied animals exposed to radiation.

Mousseau's research has found significant genetic damage and breakages in chromosomes among animals exposed to radiation in and around Chernobyl, a situation similar to that of Fukushima. Developmental abnormalities, tumors, and species decline and extinction have also been attributed to radiation exposure in that area, and are likely to also occur in Japan.

To read the story and see photos of dogs and cats living near the Fukushima nuclear plant, which was published in PBS Newshour, the Rundown Blog, click this link.

For an overall update on the situation in Japan, click this link to view a podcast more about the persistent radiation readings around the Fukushima area on the PBS Newshour website.

How Dogs Evolved from Wolves to Become Domesticated

Dogs have aided humans for thousands of years. Man's best friend has provided protection, companionship and hunting assistance since the days of the earliest human settlements. But how and when dogs evolved from wolves is a matter of debate.

 In his book "How the Dog Became the Dog — From Wolves to Our Best Friends," naturalist Mark Derr writes that wolves who attached themselves to human hunting parties for survival ultimately evolved into today's dog species.

Groups of dogs that socialized well with people split off from the wilder dogs, mated and led to the domesticated species we have today.

If you would like to read or listen to an interview with Mark Derr on National Public Radio about his book, click on this link to go to the NPR website.

Rosie, the Hyperthyroid Bodega Cat: an Epilogue

Hi Everyone,

This is "Rosie" again. You won't believe this next chapter in my life!

You remember that beautiful lady Gladys who I'm crazy about? Of course, you already know she's crazy about me, too. We've bonded — it's mutual love!

Well, after my delightful 5-day stay at Dr. Peterson's Hypurrcat facility at the Animal Endocrine Clinic where I was treated for my hyperthyroid condition, it was time to go home.

I had a ball at Dr. Peterson's, living a life of luxury. But now, instead of going back to the bodega, they decided it was best for me to go home with Gladys!

And the amazing thing is that Gladys lives in a beautiful penthouse apartment in a very posh section of NYC. I'm very very excited and happy about this turn of events, because after all the heartbreak of losing my first mistress, now I'm going home to a gorgeous penthouse apartment, living in total luxury.

Although this does seem a fitting domicile for a cat as charming as myself — I still can't believe how lucky I am! I'm going home to my new life tomorrow, and I can hardly wait!

I promise to keep you posted and fill you all in on how everything turns out.

PS: Oh, another thing. Dr. Peterson just called Gladys and told her that the radioiodine treatment worked. My hyperthyroid condition is completely cured!

The Story of Rosie, a Hyperthyroid Bodega Cat

Hello my name is "Rosie."

I'm a cat—but not your everyday, ordinary, run-of-the-mill cat, mind you.  I am, I must say, a beautiful, all-white, Turkish/Persian long-hair with stunning yellow to green eyes. People are easily attracted to me —not just for my beauty, but also for my personality. I am very special in everyone's eyes!

Let me tell you about my past:

As a kitten, I was cared for by a very lovely lady who lived in a large, lovely apartment in New York City. I was very happy with her for many years, but then, a tragic turn of events made me an orphan. My mistress suddenly passed away, and I was all alone in the world! But a kindly doorman in my building knew me well, and he decided to take me into his home. He has a lovely wife and two children, so I thought: "This is going to be a great home for me." But it was not to be— his children were very allergic to cats, and even though they loved me a lot, I could not continue to stay there.

So the kindly doorman started his search for a new home for me.

There is a small bodega in the area run by a nice man and his two sons (for those of you who live outside of the City, a "bodega" is a small deli and convenience store; there's one on every block in New York City).  The present owner has run this bodega for over 30 years. They all work long shifts, 7 days a week. He has other family overseas, so he and his sons rotate, one of them going back to visit the family about every 6 months.

Anyway, I was introduced to the owner and two sons, and they immediately loved me and adopted me as their own. So for the last 3 years, I have been "Rosie the Bodega Cat." I like it there. I see and meet many people, all day long, every day. They treat me very well, feed me, and look after me in all ways, as best as they know how. At night I guard the store, and I'm a good security guard!

Then, in the June of 2011, a wonderful thing happened to me, and my life changed once again.

A very beautiful blonde lady named Gladys, who came to the bodega occasionally, noticed me and took a shine to me. Before long, she fell in love with me and I love her very much. Gladys has been looking out for me in all respects. She comes to see me 2 or 3 times a day. As soon as I hear her voice, I come right out to see her, and she plays with me and pets me. Sometimes she'll give me a treat —I like that!

One day Gladys decided that I needed some grooming. So with the blessing of the owners of the bodega, I was to go to a big animal hospital in the neighborhood to get a bath and grooming. A luxury day at the cat spa! So one morning, I went with Gladys a few blocks to the animal hospital.

It all sounded simple enough, but alas—complications developed. It seems as though I needed a slight sedative so my groomer would have no behavioral problem while grooming me. Unfortunately, during my grooming, another big problem was found.  I had developed a rather large, ugly black tumor on my stomach, near my mammary glands.

So now I needed lots of professional veterinary care. A simple grooming turned into a major medical problem for me. Simply put, I would have to be sedated and put under anesthesia, so that they could remove that ugly tumor and have it checked for malignancy—you know: cancer!

Dr. Peterson examining Rosie

So my surgery was done on a Friday. My operation went very well. My doctor was excellent, and she also loved me very much. To tell you the truth, all the hospital employees loved me to death. They came by my kennel area often, and took me out, made a fuss over me, and played with me, and gave treats too. Not bad, luxurious living for a bodega cat! 

I stayed at the hospital for about 10 days for care and observation. I also had to wear a silly neck collar, so I could not reach my tummy and cause a healing problem by licking the incision. We cats love to groom ourselves — grooming and sleeping are big parts of our day!

I've been dubbed "Rosie, the Celebrity Cat," not just there at the hospital, but in the whole neighborhood! Look out, Hollywood, here I come! The first animated "Rosie the Cat" movie is just around the corner. By the way, good news! The tumor was benign — you know, no cancer!

Oh, I forgot to mention another complication. The doctor gave me a very comprehensive pre-operative exam. As a result, it was discovered that I had a problem common to many cats: hyperthyroidism. That's a mighty big word for a small, beautiful, white, 9-pound cat, don't you think?

So after another grooming, I went home for about 6 days to complete my recovery.  Gladys then took me to a specialty hospital: Dr. Mark E. Peterson's Animal Endocrine Clinic up on West 100th Street. At the AEC, Dr. Peterson has a Hypurrcat treatment facility where he treats cats specifically for hyperthyroidism with radioiodine.  How about that name —Hy-purr-cat? By the way, I purr a lot because I'm a very happy, content cat!

So last Sunday,  I met Dr. Peterson, who turns out to be the world's expert on my condition, having treated over 10,000 cats over his 30 year career. Now, Rosie, the Celebrity Cat will be number 10,001! He carefully examined me but spent a great deal of time petting me, which I actually enjoyed (he is very gentle!). As Dr. Peterson explained to Gladys, there are no side effects, no pain, just one little injection! And it's a very effective treatment!  And he was right: the treatment consisted of a little injection under the skin, and it really didn't hurt a bit.

Rosie in her condo at Hypurrcat

Wow, can you believe all of this? I can't, but guess what? I'm enjoying my stay here!  First, my accommodations are really nice. I'm in the Penthouse condo, high above everyone so I have a great view. I have my own large personal condo, of course, with hiding boxes, perches, litter box, alcoves and good ventilation!

Now get this, folks: I also have my own flat-screen TV that plays relaxing nature videos! I also have a window view of the rear courtyard, where I can see squirrels, and birds, eating from feeders!  Dr. Peterson and his staff are really nice to me here — I can eat as much as I want and I get lots of attention.

I can't believe all this is happening to "Little Rosie, the Bodega Cat!" What a life! I thought you would like to hear my story. I hope you like it!

But most of all, I thank you very much Gladys for your deep love and care for me! Thankfully you got over your cat allergy just in time to look after me so lovingly. You are the best, the best thing that has ever happened to me! I love you to pieces!

XOXO

Rosie

PS: After I leave Hypurrcat (I don't really want to go — the accommodations here are great and I love watching the birds),  I don't know where I'll end up, but I promise to keep you all updated as my saga continues.

Treating Cats with Hyperthyroidism: Antithyroid Drugs

In cats, hyper­thyroidism can be treated in four ways — chronic administration of an antithy­roid drug, surgical thyroidectomy, radioactive io­dine (131-I), or lifelong feeding of an ultra-low iodine diet.

The treatment of choice for an individual cat depends on several factors, including the age of the cat, presence of associated heart or kidney dis­eases or other major medical problems, availability of a skilled surgeon or radioiodine treatment facility, and owner's preference (1-4).

In this post, I’m going to discuss the use of antithyroid drugs for treating cats with hyperthyroidism. This is the most common means that veterinarians use to treat this common condition, so let’s start by discussing the pros and cons of this form of treatment.

The Advantages and Disadvantages of Antithyroid Drugs

Advantages
Chronic management with antithyroid drugs is a practical treatment option for many cats with hyperthyroidism, and offers many advantages. Medical management requires no special facilities and can be prescribed by all veterinarians (1-4). These drugs cause a rapid fall in serum thyroid hormone levels (i.e., the high serum T4 normalizes within 1-3 weeks), which may be desirable in severely affected hyperthyroid cats (5,6).

Anesthesia is avoided, as are the surgical complications associated with thyroidectomy (I’ll be discussing surgical treatment in my next post). In contrast to surgery or radioiodine treatment, hospitalization is not required with medical treatment. Finally, the initial, upfront costs of antithyroid drugs is much less than with either surgical or radioactive iodine treatment.

Disadvantages
Long-term medial management also has many disadvantages. This form of treatment is not curative, is highly dependent on owner and cat compliance, and requires regular biochemical monitoring to ensure the efficacy of treatment (1-4). Side effects are common, occurring in up to 20% of cats (1-6). Even though the initial cost of medical treatment may be far less initially, the cost of ongoing monitoring over a period of months to years can exceed that of thyroidectomy or radioiodine therapy.

These antithyroid drugs also come with other drawbacks. Since they block thyroid hormone synthesis but do not destroy the cat’s thyroid tumor, these drugs never cure the hyperthyroidism and relapse will always occur if daily medication is discontinued (1-6). Most importantly, the benign thyroid tumor — which is present in all cats with hyperthyroidism (7,8) — continues to grow and, after many months, may transform from adenoma to thyroid carcinoma in some cats (9).

Long-term medical management is best reserved for cats of advanced age or for those with concurrent diseases, and for when owners refuse either surgery or radioactive iodine. In addition to long-term treatment, medical management is also advised prior to surgical thyroidectomy to decrease the metabolic and cardiac complications associated with hyperthyroidism. Short-term medical management is often recommended as trial therapy to determine the effect of restoring euthyroidism on kidney function, especially in cats with suspected chronic kidney disease (1-4,10).

Methimazole and Carbimazole: The 2 Antithyroid Drugs

The two drugs methimazole and carbimazole are commonly recommended for managing cats with hyperthyroidism (1-6). A related drug, propylthiouracil, often used in human medicine, is not recommended for cats because of a high incidence of serious adverse reactions —especially anemia and bleeding problems (11).

Methimazole blocks thyroid hormone synthesis by inhibiting thyroid peroxidase, an enzyme involved in the oxidation of iodide to iodine, incorporation of iodine into thyroglobulin, and coupling of tyrosine residues to form T4 and T3 (12). Methimazole does not block the release of preformed thyroid hormone, so there is a delay of 1 to 3 weeks before serum T4 concentrations return to normal after initializing therapy (5, 6).

Carbimazole is a pro-drug of methimazole. That means that after oral administration of carbimazole, it is almost immediately converted to methimazole by the cat (13). So basically, it turns out that carbimazole and methimazole end up being the same drug (1-4).

Different Drug Formulations of Methimazole & Carbimazole

Methimazole Tablets
Methimazole is specifically licensed for treatment of feline hyperthyroidism both in the USA and Europe as 2.5- and 5-mg tablets (Felimazole, Dechra Veterinary Products). It is also available as a generic and brand name drug for human use (Tapazole). For most hyperthyroid cats, a starting dose of 1.25 mg to 2.5 mg methimazole is administered twice daily is recommended (1-4,14).

Carbimazole Tablets
Carbimazole is available for human use in many European countries (brand name, NeoMercazole), Australia and Japan (2-4). This drug is not available as a licensed drug in the USA, but it is available though compounding pharmacies.

As noted above, carbimazole exerts its antithyroid effect through immediate conversion to methimazole when administered orally (13). Serum concentrations of methimazole achieved after carbimazole administration are less than after a similar weight of methimazole such that a 5-mg dose of carbimazole is approximately equal to 3 mg of methimazole (3,6). Because of that, a starting dose of regular carbimazole of 2.5 mg to 5 mg twice daily is commonly recommended for restoring euthyroidism (2-4,6).

Carbimazole is often touted as having a lower incidence of adverse reactions such as vomiting and anorexia (6,15). This may be because it is tasteless whereas methimazole has a bitter taste (3,6). However, Felimazole, as licensed for veterinary use, is sugar-coated; provided the tablet is not crushed, the bitter taste is presumably avoided.

Carbimazole Tablets (Controlled-Release)
A controlled-release formulation of carbimazole (Vidalta, Intervet Schering Plough) is licensed for cats in Europe for once daily administration (16,17). This formulation is not available in the USA.

Administration of this drug with food significantly enhances its absorption (16). The starting dose for controlled release carbimazole is 15 mg administered once daily. In cats with mild hyperthyroidism (total T4 concentration <100 nmol/L or < 8 μg/dl), a 10 mg once daily is recommended (2-4,16).

Transdermal Antithyroid Drugs
Carbimazole and methimazole can be reformulated by a veterinary compounding pharmacy and applied to the non-haired inner portion of a cat’s pinnae (ear lobe) for transdermal administration (18-20). Such custom formulation increases expense of therapy and the stability of the product can never be guaranteed.  To prevent absorption of the drug through one's own skin, it is best to wear gloves or a finger cot for application, and wash your hands afterwards.

Both antithyroid drugs are generally effective in cats when administered at a dose of 1.25 mg to 2.5 mg twice daily transdermally (2-4).  One advantage of using a compounded formulation of methimazole (or carbimazole) over the 2.5- or 5-mg tablets is that it is easier to make smaller or finer dose adjustments.

Transdermal administration is associated with fewer gastrointestinal side effects than the oral route (19,21,22), but some cats resent manipulation of their ears and crusting can occur between doses leading to erythema. These problems can usually be prevented by removing any crusted material and cleaning the ear flap prior to administration.

Monitoring of Hyperthyroid Cats on Antithyroid Drug Treatment

Initial doses of the antithyroid drug vary depending on the cat’s pretreatment serum T4 value and goiter size (i.e., size of the thyroid tumor). In general, however, most cats are started on 1.25-2.5 mg of methimazole or 2.5-5 mg of carbimazole, both administered twice daily (1-4,21-23).

Initial Monitoring
Initially, cats should be reassessed after 2 to 3 weeks and a serum total T4 concentration measured. When monitoring, time of serum T4 sampling in relation to the administration of the antithyroid drug is not overly important (1-4,24). The goal of medical therapy is to maintain total T4 concentrations within the lower half of the reference range (1-4). Low serum T4 values should be avoided, however, because it has been shown that chronic hypothyroidism is deleterious to kidney function and may worsen already present chronic kidney disease (25,26).

If hyperthyroidism persists during antithyroid drug treatment, lack of owner or cat compliance should always first be eliminated as a reason for the failure of therapy. If the serum T4 concentrations remain high with proper treatment, however, the daily dose of methimazole or carbimazole can be increased in 2.5-mg increments, reassessing the cat again in 3 to 4 weeks (1-4).

Long-Term Monitoring and Treatment
For chronic management (once euthyroidism has been achieved), the daily antithyroid drug dosage is adjusted to the lowest possible dose that effectively maintains euthyroidism. Once the dosage has stabilized, the cat should be monitored every 3 to 6 months and as needed clinically. At time of each of these rechecks, a complete physical examination should be perform together with determination of a complete blood count, serum chemistry profile, and serum T4 concentration.

Relapses are common in cats treated with an antithyroid drug. Some cats will become more difficult to medicate over time, whereas others will need higher daily drug dosages to inhibit thyroid hormone secretion as their thyroid tumors continue to grow larger and larger (27).

It is important to keep the serum T4 concentration within the mid-normal range and not have even mildly high or high-normal values. For example, if the T4 reference range is listed as 0.8-4.0 μg/dl (10-50 nmol/L), my goal is maintain the T4 values between 1.5-2.5 μg/dl (20-32 nmol/L). Recent research indicates that hyperthyroidism may contribute to the development or progression of chronic renal disease in cats (28-30).  Leaving a hyperthyroid cat untreated (or poorly regulated with methimazole or carbimazole) may therefore be detrimental to long-term kidney function and is never recommended.

During long-term treatment, it is again important to avoid inducing hypothyroidism, which may be deleterious to the cat’s kidney function (25,26). If hypothyroidism is suspected (which can develop even if the T4 is low-normal), a complete thyroid panel is recommended, including determination of the serum concentrations of total T4, free T4, T3, and TSH (see my previous blog posts on diagnostic testing for more information about these tests). The findings of low serum free T4 with high TSH concentrations is diagnostic for iatrogenic hypothyroidism; in those cats, the daily dose of methimazole  should be decreased.

Because antithyroid medications have no effect on the underlying lesion, the thyroid nodules continue to grow larger and larger over time. This may necessitate an increased daily dose with time. In some cats, large enough dosages can no longer be administered to control the hyperthyroidism and surgery or radioiodine is needed to control the hyperthyroidism (27).

Side Effects & Adverse Reactions

Most clinical adverse reactions occur within the first 3 months of therapy (1-4). Mild clinical side effects of vomiting, anorexia, or depression occur in approximately 10-15% of cats, usually within the first 3 weeks of therapy (4,5). In most cats, these reactions are transient and do not require permanent drug withdrawal.

Mild Side Effects

Figure 1: Facial excoriations
due to methimazole

Early in the course of drug therapy, mild and transient hematological abnormalities, including leucopenia (low total white blood cell count), lymphocytosis (high lymphocyte count), or eosinophilia (high eosinophil count) develop in up to 15% of cats without any apparent clinical effect (1-6).

Self-induced excoriations of the head and neck (from scratching) occasionally develop, usually within the first 6 weeks of therapy (see Figure 1).

Less commonly, generalized enlargement of lymph nodes may develop during drug treatment (31). If either of these adverse effects occur, the drug must be stopped and another form of treatment given.

Life Threatening Side Effects

Figure 2: Bleeding from gums due
to methimazole

More serious hematological complications occur in less than 5% of cats and include a severe lowering of the white blood cell count (agranulocytosis) or platelet count (thrombocytopenia).  Liver dysfunction, characterized by marked increases in all hepatic enzymes, develops in less than 2% of cats (1-5).

Rarely, cats may also develop a severe bleeding tendency during drug treatment (see Figure 2) (5,32). All of these adverse effects are reversible upon discontinuation of the medication.

The Bottom Line

Short-term or chronic management with antithyroid drugs provides a useful treatment option for many cats with hyperthyroidism. However, this treatment does not cure the disease and requires daily medication for the rest of the cat's life.  Like any prescription drug, methimazole or carbimazole can produce adverse side effects, which may be life-threatening is some cats. For all of these reasons, antithyroid drugs will never be the "treatment of choice" for all cats with hyperthyroidism.

References

1. Peterson ME: Hyperthyroidism in cats. In: Melian C (ed): Manual de Endocrinología en Pequeños Animales (Manual of Small Animal Endocrinology). Barcelona, Multimedica, 2008; 127-168.
2. Baral R, Peterson ME. Thyroid diseases. In: Little, S. (ed), The Cat: Clinical Medicine and Management. Philadelphia, Elsevier Saunders 2012; in press.
3. Mooney CT, Peterson ME: Feline hyperthyroidism, In: Mooney C.T., Peterson M.E. (eds), Manual of Canine and Feline Endocrinology (Fourth Ed), Quedgeley, Gloucester, British Small Animal Veterinary Association, 2012; in press.
4. Peterson ME: Hyperthyroidism in cats, In: Rand, J (ed), Clinical Endocrinology of Companion Animals. New York, Wiley-Blackwell, 2012; in press.
5. Peterson ME, Kintzer PP, Hurvitz AI. Methimazole treatment of 262 cats with hyperthyroidism. Journal of Veterinary Internal Medicine 1988;2:150–157. 
6. Mooney CT, Thoday KL, Doxey DL. Carbimazole therapy of feline hyperthyroidism. Journal of Small Animal Practice 1992;33:228–235. 
7. Gerber H, Peter H, Ferguson DC, et al. Etiopathology of feline toxic nodular goiter. Veterinary Clinics of North America Small Animal Practice 1994;24:541-565.
8. Peterson ME, Ward CR. Etiopathologic findings of hyperthyroidism in cats. Veterinary Clinics of North America Small Animal Practice 2007;37:633-645.
9. Hibbert A, Gruffydd-Jones T, Barrett EL, et al. Feline thyroid carcinoma: diagnosis and response to high-dose radioactive iodine treatment. Journal of Feline Medicine and Surgery 2009;11:116-124.
10. Becker TJ, Graves TK, Kruger JM, et al. Effects of methimazole on renal function in cats with hyperthyroidism. Journal of the American Animal Hospital Association 2000;36:215–223. 
11. Peterson ME, Hurvitz AI, Leib MS, Cavanagh PG, Dutton RE. Propylthiouracil-associated hemolytic anemia, thrombocytopenia, and antinuclear antibodies in cats with hyperthyroidism. Journal of the American Veterinary Medical Association 1984;184:806-808. 
12. Cooper DS. Antithyroid drugs. New England Journal of Medicine 2005;352:905-917.
13. Peterson ME, Aucoin DP. Comparison of the disposition of carbimazole and methimazole in clinically normal cats. Research in Veterinary Science 1993;54:351–355. 
14. Plumb DC. Plumb's Veterinary Drug Handbook (7th Ed). PharmaVet Inc, Stockholm, Wisconsin 2011.
15. Bucknell DG. Feline hyperthyroidism: spectrum of clinical presentions and response to carbimazole therapy. Australian Veterinary Journal 2000;78:462-465. 
16. Frénais R, Burgaud S, Horspool LJ. Pharmacokinetics of controlled-release carbimazole tablets support once daily dosing in cats. Journal of Veterinary Pharmacology and Therapeutics 2008;31:213-219.
17. Frenais R, Rosenberg D, Burgaud S, et al. Clinical efficacy and safety of a once-daily formulation of carbimazole in cats with hyperthyroidism. Journal of Small Animal Practice 2009;50:510-515. 
18. Hoffman S, Yoder A, Trepanier L. Bioavailability of transdermal methimazole in a pluronic lecithin organogel (PLO) in healthy cats. Journal of Veterinary Pharmacology and Therapeutics  2002;25:189-193. 
19. Hoffman SB, Marks SL, Taboada J et al. Transdermal methimazole treatment in cats with hyperthyroidism. Journal of Feline Medicine and Surgery 2003;5:77–82. 
20. Buijtels JJ, Kurvers IA, Galac S et al. Transdermal carbimazole for the treatment of feline hyperthyroidism, Tijdschrift voor Diergeneeskunde 2006;131:478-482. 
21. Trepanier LA. Pharmacologic management of feline hyperthyroidism. Veterinary Clinics of North America: Small Animal Practice 2007;37:775-788. 
22. Trepanier LA. Medical management of hyperthyroidism. Clinical Techniques in Small Animal Practice 2006;21:22-28. 
23. Trepanier LA, Hoffman SB, Knoll M, et al. Efficacy and safety of once versus twice daily administration of methimazole in cats with hyperthyroidism. Journal of the American Veterinary Medical Association 2003;222:954–958. 
24. Rutland BE, Nachreiner RF, Kruger JM. Optimal testing for thyroid hormone concentration after treatment with methimazole in healthy and hyperthyroid cats. Journal of Veterinary Internal Medicine 2009;23:1025-1030. 
25. Williams TL, Peak KJ, Brodbelt D, et al. Survival and the development of azotemia after treatment of hyperthyroid cats. Journal of Veterinary Internal Medicine 2010;24:863-869. 
26. Williams T, Elliott J, Syme H. Association of iatrogenic hypothyroidism with azotemia and reduced survival time in cats treated for hyperthyroidism. Journal of Veterinary Internal Medicine 2010;24:1086-1092. 
27. Peterson ME. Treatment of severe, unresponsive, or recurrent hyperthyroidism in cats. Proceedings of the 2011 American College of Veterinary Internal Medicine Forum. 2011;104-106.
28. Lapointe C, Bélanger MC, Dunn M, et al. N-acetyl-beta-D-glucosaminidase index as an early biomarker for chronic kidney disease in cats with hyperthyroidism.  Journal of Veterinary Internal Medicine 2008;22:1103-1110. 
29. van Hoek I, Lefebvre HP, Peremans K, et al. Short- and long-term follow-up of glomerular and tubular renal markers of kidney function in hyperthyroid cats after treatment with radioiodine. Domestic Animal Endocrinology 2009;36:45-56.  
30. van Hoek I, Meyer E, Duchateau L, et al. Retinol-binding protein in serum and urine of hyperthyroid cats before and after treatment with radioiodine. Journal of Veterinary Internal Medicine 2009;23:1031-1037. 
31. Niessen SJ, Voyce MJ, de Villiers L, et al. Generalised lymphadenomegaly associated with methimazole treatment in a hyperthyroid cat. Journal of Small Animal Practice 2007;48:165-168. 
32. Randolph JF, DeMarco J, Center SA, et al. Prothrombin, activated partial thromboplastin, and proteins induced by vitamin K absence or antagonists clotting times in 20 hyperthyroid cats before and after methimazole treatment. Journal of Veterinary Internal Medicine 2000;14:56-59. 

Diet and Nutritional Management of Hyperthyroid Cats

Proper nutrition plays an extremely important role in the treatment of a cat with hyperthyroidism. Hyperthyroid cats develop muscle wasting as well as many metabolic complications because of their disease. Therefore, they have special dietary needs and require sufficient amounts of all essential nutrients in their daily diets. This includes adequate amounts of high-quality proteins, fat, minerals, vitamins, and water.

The question, “What’s the best diet to feed my hyperthyroid cat?” is an extremely common one that I get from concerned cat owners. In this post, I will discuss the ideal food composition and nutrients that I believe hyperthyroid cats should be fed.

The Many Metabolic Problems Facing the Hyperthyroid Cat

When secreted in excess, thyroid hormones have profound metabolic effects on the whole body, and dysfunction of multiple organ systems is common in hyperthyroid cats (1-3).

Weight Loss and Muscle Wasting

Weight loss, despite a normal to increased appetite, is the classic and most common sign seen in cats with hyperthyroidism (1-3). These cats lose weight because their hyperthyroidism accelerates their metabolic rate and body’s energy expenditure. In other words, they are burning up their food calories faster than they can consume their daily meals.

It’s important to realize that hyperthyroidism is a catabolic wasting state, in which a "breaking down" of the body occurs no matter how much nutritional intake occurs. The progressive weight loss and muscle wasting that is so characteristic of feline disease is caused by an increased rate of fat and muscle protein breakdown (4,5).

When hyperthyroid cats initially lose weight, this can be first noticed as a loss of muscle mass over the cat’s lower back. Despite this loss of muscle mass, most mildly hyperthyroid cats retain their “belly” during the initial stages of their thyroid disease and may even have a higher than ideal body condition score.

With time, severe muscle wasting, emaciation, cachexia, and death from starvation can occur if the cat’s hyperthyroidism is left untreated (1-3). In hyperthyroidism, the cat’s body consumes its own muscle tissue to get the protein it needs to sustain its carnivorous life.

Even with treatment of hyperthyroidism, recovery of muscle mass and function may be prolonged, lasting several weeks to months. This is especially true if these cats are not provided with enough protein in their diet to rebuild and maintain their lost muscle mass.

High Blood Glucose, Insulin Resistance, and Diabetes Mellitus
Hyperthyroid cats can also develop profound changes in carbohydrate metabolism (glucose and insulin metabolism). Slightly high resting blood glucose (sugar) concentrations are common in hyperthyroid cats, which is generally attributed to a “stress” reaction.

However, the actual metabolic changes are actually much more complicated. Hyperthyroidism frequently causes moderate to severe insulin resistance (6,7), which is a physiological condition where the natural hormone insulin becomes less effective at lowering blood glucose levels. This insulin resistance is associated with a decreased glucose clearance, which is indicative of a prediabetic state. Occasionally, an untreated hyperthyroid cat will even go on to develop full-blown diabetes mellitus. Many of these diabetic cats are difficult to regulate with insulin therapy but treatment of their concurrent hyperthyroid state generally improves diabetic control.

Unfortunately, the insulin resistance and associated prediabetic state — so common in hyperthyroid cats —do not always improve despite successful treatment of hyperthyroidism (7). This indicates that hyperthyroid cats may have long-lasting alterations of carbohydrate metabolism that cannot always be reversed by treatment. In accord with that, some of these hyperthyroid cats (not diabetic at time of diagnosis) will go on to develop overt diabetes mellitus in the months to years after treatment of hyperthyroidism.

Sarcopenia of Aging
In addition to loss of muscle mass from the catabolic effects of thyroid hormone excess, cats also tend to lose muscle mass as they age, independent of their thyroid status. This phenomenon, referred to as sarcopenia of aging, is also common in elderly human beings (8-10). The term age-related sarcopenia is derived from Greek (meaning "poverty of flesh") and is characterized by a degenerative loss of skeletal muscle mass and strength, as well as increased muscle fatigability.

In adult cats, maintenance energy requirements decrease by about 3% per year until the age of 11 years, and then actually start to increase again (11). This contributes to a tendency of senior cats to lose muscle mass if their energy needs are not met. Lean body mass of aging cats drops dramatically after 12 years of age, and by age 15, cats may have a mean lean tissue mass that is a third less than cats aged 7 years or less (11, 12). Body fat also tends to progressively decrease in cats after the age of 12 years; this combination of reduced lean mass and body fat contributes to weight loss experienced by many elderly cats.

The ability to digest protein is also compromised in many geriatric cats. After the age of 14 years, one-fifth of geriatric cats have reduced ability to digest protein (11-13). Reduced protein digestibility in geriatric cats seems to occur in parallel with reduction of lean tissue and it might predispose them to negative nitrogen balance. (14).

Although moderation of calorie intake might be suitable for some mature cats, it does not appear to match the needs of most geriatric cats. In contrast, it seems more logical to use highly digestible, energy-dense food for geriatric cats in order to prevent or slow their decline in body weight and lean body tissue (11,14,15). Reducing protein intake in geriatric cats, at a time when lean tissue has been lost, is contraindicated. Geriatric cats seem to have nutritional requirements closer to kittens than to mature adult cat.

Diet Recommendations for Hyperthyroid Cats

Cats are true obligate carnivores (16-20). This means they must eat meat to survive; cats cannot be vegetarians. To me, it makes a great deal of sense to feed hyperthyroid cats, a diet with a composition close to what they would be getting in the wild. That would be a diet composed of approximately 50-60% protein, 5-10% carbohydrates, and 30-50% fat (21-23).

High Dietary Protein
As obligate carnivores, cats are unique in their need for large amounts of dietary protein (specifically, dispensable nitrogen) that separates them from omnivores and herbivore species (16-20). This absolute requirement for dietary protein intake in cats is critically important when formulating a diet for hyperthyroid cats, in which protein catabolism and muscle wasting is universally present.

Protein is the primary macronutrient responsible for maintenance of muscle mass. Restoring and preserving any remaining muscle tissue in cats treated for hyperthyroidism depends upon the cat consuming a diet with sufficient amounts of high-quality protein. In addition, this recommendation for higher amounts of dietary protein does not change once euthyroidism has been restored. The dogma that all older cats should be fed reduced energy “senior” diets must be questioned based on what is now known about the increasing energy requirements and nutritional needs of older cats (10,11).

In most geriatric cats, logic dictates the use of highly digestible, energy-dense foods to mitigate the decline in body weight and lean body tissue and help avoid protein:calorie malnutrition (10,14,15). Protein reduction for this geriatric life stage, at a time when lean tissue is being lost, is contraindicated. Geriatric cats seem to have nutritional requirements closer to kittens than to mature adult cats.

Low Dietary Carbohydrates
Since most of these cats also have subclinical diabetes —as evidenced by their mild hyperglycemia, glucose intolerance, and insulin resistance — feeding a low carbohydrate diet (<10% of total calories) also is strongly recommended. This is what most endocrinologists (myself included) also recommend in cats with diabetes mellitus (24-26).

Feeding a low carbohydrate diet will improve insulin sensitivity, reduce the need for exogenous insulin, and help stabilize glucose metabolism in these cats (24-26). This may prevent the development of overt diabetes and control long-term obesity in these cats after successful control of the hyperthyroidism.

Concurrent Kidney Disease in the Hyperthyroid Cat
Concurrent chronic kidney disease (CKD) is common in hyperthyroid cats, occurring in up to 30% of cases. Cats with advanced CKD — IRIS Stage 3 or 4 — may need lower amounts of dietary protein to lessen uremic episodes (27). However, at least in early to mid-stage renal disease, lowering of the serum phosphate concentration is much more important in management than dietary protein restriction, and this can be easily accomplished with phosphate binders without lowering the protein content of the diet (28,29). For an explanation of the IRIS system used by veterinarians to stage CKD in cats, see this link: http://www.iris-kidney.com.

It may seem impossible, but no studies have conclusively demonstrated that severe restriction of protein alone will prevent further deterioration of kidney function in cats (30). The major problem that I have with some of the prescription kidney diets is that they restrict protein to the point that some cats — especially those with concurrent hyperthyroidism —will continue to catabolize their own muscle mass despite adequate control of the thyroid condition.

Selecting a Commercially Prepared Diet for Your Hyperthyroid Cat

To me, it makes a great deal of sense to feed hyperthyroid cats a diet with a composition close to what they would be getting in the wild. To that end, I'm looking for a diet that is composed of approximately 50% protein and <10% carbohydrates (21-23). Because older cats also loss lean muscle mass in association with the “sarcopenia of aging,” this diet composition needs to be continued even after one treats the cat’s hyperthyroidism and restores euthyroidism.

Determine the Composition of the Diet
Check out this website (http://binkyspage.tripod.com/foodfaq.html), which gives you a breakdown of the composition of the various prescription and over-the-counter diets. This website uses metabolizable energy (ME) values to evaluate food composition— in other words, it gives you the percent calories that comes from the protein, fat, and carbohydrate fractions of the diet, and allows us to compare various diets without worrying about their different water levels (31).

It turns out that many of the over-the-counter diets have a better composition of protein and carbohydrates than you might have thought — even better than many of the more expensive prescription diets. Very few of my hyperthyroid cat patients require a prescription diet to fulfill their nutritional needs.

The composition of almost all dry food cat diets are much too high in carbohydrates and most are too low in protein content. That is why I believe it's best to limit the amount of dry food that is fed to cats, or even better, not feed dry food at all.

Examine the Ingredients of the Diet
Once we have selected a few diets with the required composition breakdown of carbohydrates, protein, and fat, we next have to look at the ingredient list (32). Not all of the proteins in cat foods are equal in quality. Remember that quality meat is the best ingredient in a food and that meat by-products are a close second. Some vegetable and grains are fine, but they may supply a less bioavailable form of protein for cats and should not be the primary source of dietary protein.

When deprived of protein, carnivores will continue to break down muscle tissue to create the energy they need. By feeding only high-quality protein diets, we will help restore the cat’s muscle mass and improve strength and agility.

Choosing A Pet Food Company
In addition to looking at the composition and ingredients, we have to ensure that all of the essential nutrients are present in the diet. Some of the cat foods marketed as "holistic or natural" may not actual be totally balanced or contain all of the essential amino acids that a cat needs. The best way to determine if diet is totally nutritious is to examine the diet's nutritional profile, which shows the levels or concentrations of all essential nutrients (amino acids, fat, mineral, and vitamin) in the pet food (33).

For cat owners, I recommend that they choose two or more pet food companies known to have a good track record and feed those foods. I also choose foods that carry an AAFCO feeding claim to be complete and balanced for an adult or senior cat. I would be very careful in choosing a smaller company as the primary supplier for your cat's food. Small pet food companies are less likely to have veterinary nutrition specialists on their staff, and therefore, their diets may not always balanced and could result in nutritional deficiencies.

In addition to rotating brands, I also like to feed a variety of different flavors. Why? I believe it's safer to rotate between brands because companies formulate their diets differently. It also helps to determine which brands and flavors and foods the cat prefers; since diet preferences may change over time, varying the food helps maintain a good appetite, especially as the cat ages.

Homemade Diets for Your Hyperthyroid Cat

Homemade diets can certainly be as good as any commercial diet if properly formulated and contain all of the essential nutrients needed for the older cat. The advantage of these diets is that you know exactly what ingredients they contain (34, 35). These homemade diets also allow for people to choose exactly what type of ingredient to include in the food (e.g., organic, kosher, or biodynamic ingredients).

The risk of homemade diets being improperly formulated, however, is very high unless the cat owner seeks out a veterinary nutritionist to help formulate a properly balanced diet (34, 35). I've included the links for some of the available nutritional consultation services below:

• Veterinary Nutritional Consultations — PetDiets.com  
• DVM Consulting — BalanceIT.com 
• Dr. Susan Wynn, Georgia Veterinary Specialists — SusanWynn.com  
• Clinical Nutrition Program, University of Missouri  
• Veterinary Nutrition Service, University of Tennessee College of Veterinary Medicine  

All of these services are operated by or have board-certified veterinary nutritionist on staff. Some of these sites may require your regular veterinarian to contact them for the information, whereas others will help you directly in formulating a balanced and complete diet.  It is important to stress the need for a higher protein/lower carbohydrates diet for your hyperthyroid cat — again, that is an important factor that is not widely appreciated, even among veterinary nutritionists.

The use of uncooked meat, organs, and eggs in homemade cat food recipes can be a reason for particular concern, especially if essential safe-handling practices are not followed. Raw meat can be contaminated with microorganisms that have the potential to cause infection or food poisoning, thus posing a public health risk (34-36).  Although feeding a raw diet may be the most "natural" way to provide feline nutrition and many strong arguments have been made about why raw is better (37-39), there is no clear scientific evidence that feeding raw meat has a nutritional advantage over feeding cooked meat. Given the potential health risks, the FDA does not advocate feeding raw meat, poultry, or seafood to pets (36).

If you do decide to feed a raw diet to your cat, whole raw diets for cats are available for purchase online (e.g., felinespride.com). These diets are handled and prepared carefully by the processor, frozen immediately to help prevent bacterial contamination, and kept frozen until they are delivered to your door.

If a diet is unsafe to eat or fails to provide all of the essential nutrients, a homemade cooked or raw diet provides the worst kind of nutrition. Unless one is highly dedicated and becomes knowledgeable to ensure that the homemade diet is both safe and balanced, it's generally best to stick with the commercial, canned diets, selecting them based on the criteria listed above.

The Bottom Line 

Proper nutrition plays an extremely important supportive role in the management of a cat with hyperthyroidism, which needs to be maintained even after successful treatment of the cat's hyperthyroid state. These cats should be fed a balanced and complete diet, ideally containing relatively low amounts of carbohydrates and higher amounts of protein.  This diet composition will help restore and preserve the muscle mass that has been lost as a result of increased muscle protein breakdown characteristic of hyperthyroidism.

If commercial canned food is fed, feed balanced food with healthy ingredients from more than one good company. If you decide to go with a homemade diet, get the recipe balanced and formulated by a veterinary nutritionist. And of course, continue to check in with your veterinarian for regular physical and biochemical examinations to help pick up any emerging problems that may develop as time goes on.

References

1. Peterson ME, Kintzer PP, Cavanagh PG, et al. Feline hyperthyroidism: pretreatment clinical and laboratory evaluation of 131 cases. Journal of the American Veterinary Medical Association 1981;183:103-110. 
2. Joseph RJ, Peterson ME. Review and comparison of neuromuscular and central nervous system manifestations of hyperthyroidism in cats and humans. Progress in Veterinary Neurology 1992;3:114-119. 
3. Baral R, Peterson ME: Thyroid Diseases, In: Little, S. (ed), The Cat: Clinical Medicine and Management. Philadelphia, Elsevier Saunders, 2012;571-692 
4. Morrison WL, Gibson JN, Jung RT, Rennie MJ. Skeletal muscle and whole body protein turnover in thyroid disease. European Journal of Clinical Investigation 1988;18:62–68. 
5. Riis AL, Jørgensen JO, Gjedde S, et al. Whole body and forearm substrate metabolism in hyperthyroidism: evidence of increased basal muscle protein breakdown. American Journal of Physiology: Endocrinology and Metabolism 2005; 288:E1067-1073. 
6. Hoenig M, Ferguson DC. Impairment of glucose tolerance in hyperthyroid cats. Journal of Endocrinology 1989;121:249-251. 
7. Hoenig M, Peterson ME, Ferguson DC. Glucose tolerance and insulin secretion in spontaneously hyperthyroid cats. Research in Veterinary Science 1992;53:338-341. 
8. Short KR, Nair KS. Mechanisms of sarcopenia of aging. Journal of Endocrinological Investigation 1999;22(5 Suppl):95-105. 
9. Fujita S, Volpi E. Nutrition and sarcopenia of ageing. Nutrition Research Reviews 2004;17:69-76. 
10. Wolfe RR. Sarcopenia of aging: Implications of the age-related loss of lean body mass. Proceedings of the Nestlé Purina Companion Animal Nutrition Summit: Focus on Gerontology. St. Louis, MO. 2010, pp. 12-17. 
11. Little S: Evaluation of the senior cat with weight loss, In: Little, S. (ed), The Cat: Clinical Medicine and Management. Philadelphia, Elsevier Saunders, in press. 
12. Perez-Camargo G: Cat nutrition: What is new in the old? Compendium for Continuing Education for the Practicing Veterinarian 2004;26 (Suppl 2A):5-10. 
13. Patil AR, Cupp C, Pérez-Camargo G. Incidence of impaired nutrient digestibility in aging cats. Nestlé Purina Nutrition Forum Proceedings. 2003;26,2(A):72. 
14. Wakshlag JJ. Dietary protein consumption in the healthy aging companion animal. Proceedings of the Nestlé Purina Companion Animal Nutrition Summit: Focus on Gerontology. St. Louis, MO. 2010, pp. 32-39. 
15. Sparkes AH. Feeding old cats— An update on new nutritional therapies. Topics in Companion Animal Medicine 2011;26:37-42. 
16. MacDonald ML, Rogers QR, Morris JG. Nutrition of the domestic cat, a mammalian carnivore. Annual Review of Nutrition 1984;4:521-562. 
17. Morris JG. Idiosyncratic nutrient requirements of cats appear to be diet-induced evolutionary adaptations. Nutrition Research Reviews 2002;15:153-168. 
18. Zaghini G, Biagi G. Nutritional peculiarities and diet palatability in the cat. Veterinary Research Communications 2005;29, Suppl 2:39-44 
19. Zoran DL. The carnivore connection to nutrition in cats. Journal of the American Veterinary Medical Association 2002;221:1559-1567. 
20. Zoran DL, Buffington CA. Effects of nutrition choices and lifestyle changes on the well-being of cats, a carnivore that has moved indoors. Journal of the American Veterinary Medical Association 2011;239:596-606. 
21. Myrcha A, Pinowski J. Weights, body composition and caloric value of post-juvenile molting European tree sparrows. Condor 1970;72:175–178. 
22. Vondruska JF. The effect of a rat carcass diet on the urinary pH of the cat. Companion Animal Practice 1987;1:5-9. 
23. Crissey SD, Slifka KA, Lintzenich BA. Whole body cholesterol, fat, and fatty acid concentrations of mice (Mus domesticus) used as a food source. Journal of Zoo and Wildlife Medicine 1999;30:222-227. 
24. Rucinsky R, Cook A, Haley S, et al. AAHA diabetes management guidelines for dogs and cats. Journal of the American Animal Hospital Association 2010;46:215-224. 
25. Frank G, Anderson W, Pazak H, et al. Use of a high-protein diet in the management of feline diabetes mellitus. Veterinary Therapeutics 2001;2:238-246. 
26. Rand JS, Fleeman LM, Farrow HA, et al. Canine and feline diabetes mellitus: nature or nurture? The Journal of 2004;134(8 Suppl):2072S-2080S. 
27. Plotnick A. Feline chronic renal failure: Long-term medical management. Compendium for Continuing Education for the Practicing Veterinarian 2007;29:342-324, 346-350. 
28. Kidder AC, Chew D. Treatment options for hyperphosphatemia in feline CKD: what's out there? Journal of Feline Medicine and 2009;11:913-924. 
29. Schmidt B, Spiecker-Hauser U, Murphy M. Efficacy and safety of Lantharenol on phosphorus metabolism in cats with chronic kidney disease. American College of Veterinary Internal Medicine Forum, 2008. 
30. Ross SJ, Osborne CA, Kirk CA, et al. Clinical evaluation of dietary modification for treatment of spontaneous chronic kidney disease in cats. Journal of the Veterinary Medical Association 2006;229:949-957. 
31. Laflamme DP. Determining metabolizable energy content in commercial pet foods. Journal of Animal Physiolology and Animal Nutrition (Berlin). 2001; 85:222-230. 
32. Thompson A. Ingredients: where pet food starts. Topics in Companion Animal Medicine 2008;23:127-132. 
33. FDA. Selecting nutritious pet foods.  
34. Remillard RL. Homemade diets: attributes, pitfalls, and a call for action. Topics in Companion Animal Medicine 2008;23:137-142. 
35. Schenck PA. Home-Prepared Dog and Cat Diets. Second Edition. Wiley-Blackwell, Ames, Iowa. 2010.
36. FDA. Is it safe for me to provide my pet with a raw food diet?
37. Hodgkins E. Feeding raw meat to your cat — is it safe and sensible? In: Your Cat: Simple New Secrets to a Longer, Stronger Life. Thomas Dunne Book, New York. 2007;181-188.
38. Feline Nutrition Education Society. Just what is raw feeding, anyway?
39. Pierson LA, CatInfo.org. Making cat food.