Managing Addison's Dogs with Concurrent, Uncontrolled Diabetes

I have a 10-year old male Terrier dog named Scooter who now weighs in at 11 pounds (5 kg). He was originally diagnosed diabetes mellitus that we could not get regulated with Vetsulin, even at doses as high as 8 units twice daily. 

Scooter was subsequently diagnosed with with pituitary-dependent Cushing's disease and was treated with mitotane (Lysodren). Once we got the Cushing's disease under control, his daily insulin requirements fell to 3 units twice a day, and the diabetes was well regulated based on glucose curves done at my vet's hospital. However, after a few months of treatment with mitotane, it was apparent that Scooter had been severely overdosed with the medicine, which resulted in complete adrenal insufficiency and threw him into a severe Addison's crisis. It was a near death experience for him, but he has pulled threw and is now doing much better off of the mitotane and on treatment for his iatrogenic Addison's disease. 

Now we have spent the last 3 months trying to stabilize his iatrogenic Addison's disease and concurrent diabetes. Currently, he is on 2.5 mg of fludrocortisone (Florinef) twice day along with 1.25 mg of prednisone twice daily. The Florinef dose has had to be gradually increased to keep his serum electrolytes (sodium and potassium) within their proper ratio and ranges. Based on his last blood test, we may have to increase it yet again, since his serum potassium remains slightly high. 

To make matters even worse, his diabetes is now completely out of control, as evidenced by his intense thirst and excessive urinations with heavy amount of glucose in the urine. Serial blood glucose monitored done at my veterinarian's clinic confirms that the blood glucose readings remain very high throughout the day. We have gradually increased the insulin dose back up to 7 units twice daily, but it just doesn't seem to be working at all at this point. 

What do you recommend that I do? We need to get the Addison's disease controlled but as we have raised the doses of the Florinef and prednisone, Scooter's diabetes is getting worse! My vet has suggested that I transition Scooter from the Florinef tablets to Percorten injections in order to stabilize his serum electrolytes. He also told me that the Florinef contains some steroid activity which may be contributing to his high insulin doses.  Is the steroid in Florinef any less hard on him than the prednisone?   

Any advice would be greatly appreciated. 

My Response: 

With Scooter, we need to address both his poorly-regulated Addison's disease and his uncontrolled diabetes, as well as the increased thirst (polydipsia) and urination (polyuria). There is a lot going on with Scooter, so let's take one problem at a time.

Mineralocorticoid replacement: Florinef vs. Percorten-V? 
For mineralocorticoid replacement for dogs with Addison's disease, either oral fludrocortisone acetate (Florinef) or injectable desoxycorticosterone pivalate (DOCP; Percorten-V) can be used successfully (1-3).

In your dog, however, I would definitely make the switch to Percorten-V. Some dog's just don't respond very well to treatment with Florinef, and it's not uncommon for dogs to require increasing doses of daily Florinef over time to control the serum electrolyte concentrations (1-3). With high doses of Florinef, this can lead to signs of increased thirst and urination, and may also lead to problems with management of diabetes, as you are seeing in Scooter.

Since you are having problems controlling the serum electrolytes, I'd recommend starting with the label dose of 2.2 mg/kg, injected every 25-30 days (4). If this drug works to stabilize the serum sodium and potassium levels (and I expect that it will), then we can try to gradually lower the Percorten dosage after a few weeks to months (e.g., I generally try reducing the dose by 10% or so each month). Many dogs will maintain normal serum electrolyte levels on doses between 1-1.5 mg/kg per month, and a few will even need less (1,5).

Glucocorticoid supplementation in Addison's disease
Now let's next turn to your dog's glucocorticoid needs. Dogs with Addison's disease, either spontaneous or iatrogenic (that is, drug-induced, as it was in Scooter), will require replacement glucocorticoids (e.g., prednisone or prednisolone) in addition to the mineralocorticoid supplementation (1-3). Some dogs will do fine without any glucocorticoid supplementation, but the vast majority of dogs will feel better with a small daily dose of glucocorticoid administered daily. Since we know that these dogs cannot secrete normal amounts of cortisol, it certainly makes a great deal of sense to use low-dose glucocorticoid replacement.

Unfortunately, many dogs with Addison's disease are treated with too much glucocorticoid. Remember that our goal with glucocorticoid supplementation is to provide the same amount of steroid that the dogs would normally produce if their adrenals had not failed.

For dogs, the daily glucocorticoid maintenance dose for prednisone is only 0.1-0.2 mg/kg/day (3), so that calculates out to only 0.5-1.0 mg per day for Scooter, quite a bit lower that what you are currently giving (2.5 mg per day). That would certainly be enough to cause an increased thirst by itself, but would also contribute to glucocorticoid-induced insulin resistance, making the diabetes uncontrollable despite the higher insulin doses.

Therefore, we should try to lower the prednisone dosage first down to 1.0 mg once daily (or divided). If he is doing well clinically (i.e., normal appetite and no vomiting), then the dose can be lowered even further, down to 0.5 mg per day. Prednisone or prednisolone are available in 1-mg tablets, as well as an oral solution, making it possible to administer these smaller dosages (6,7).

Florinef also contains significant glucocorticoid activity
In addition to the fact that Addison's dogs are commonly overdosed with prednisone, it's very important to realize that fludrocortisone acetate also possesses moderate glucocorticoid activity, as well as having marked mineralocorticoid potency (2,3). By comparison, fludrocortisone has 10-times the glucocorticoid activity and 125-times the mineralocorticoid activity of cortisol, the glucocorticoid hormone secreted by the adrenal gland. In this regard, fludrocortisone is very different than Percorten-V, which possess no glucocorticoid activity (2,3).

For the dog with Addison's disease, a glucocorticoid is a glucocorticoid —it makes no difference to Scooter if this glucocorticoid activity comes from prednisone or from the Florinef.  This potent glucocorticoid activity of fludrocortisone explains why some dogs will develop polydipsia and polyuria, common side effects associated with higher-dose glucocorticoid treatment in dogs (8). This is another reason why we need to get Scooter off of the Florinef and switch to the Percorten-V.

Glucocorticoid-induced insulin resistance
In all likelihood, the reason for Scooter's poorly controlled diabetes is related to insulin resistance associated with glucocorticoid excess (9,10). By stopping the Florinef and providing mineralocorticoid replacement with Percorten-V instead, we will remove one source of excess glucocorticoid. Lowering his daily prednisone dose will also help.

As we remove the cause of the insulin resistance, the dose of insulin will again fall. You should monitor Scooter closely during this period to ensure that insulin overdosage and hypoglycemia do not occur, and lower the insulin dose as needed.

Don't forget to rule out urinary tract infections
Finally, don't forget that diabetic dogs, no matter what the cause, will commonly develop urinary tract infections. Think about it: a bladder full of sugar-laden urine is a perfect breeding ground for bacteria to thrive! Such urinary tract infections will also commonly contribute to insulin resistance (9,10) but can also lead to kidney failure, if the infection ascends from the bladder up to the kidneys.

For this reason, I always recommend checking a complete urinalysis and urine culture in all dogs (and cats) with insulin resistance. However, even if the diabetes is well-controlled, I still recommend doing a urinalysis with culture twice yearly in all of my diabetic patients.

References: 

1. Kintzer PP, Peterson ME. Treatment and long-term follow-up of 205 dogs with hypoadrenocorticism. J Vet Intern Med 1997;11:43-49. 
2. Church DB. Canine hypoadrenocorticism In: Mooney CT, Peterson ME, eds. BSAVA Manual of Canine and Feline Endocrinology. Fourth ed. Quedgeley, Gloucester: British Small Animal Veterinary Association, 2012;156-166.
3. Kintzer PP, Peterson ME. Canine hypoadrenocorticism In: Bonagura JD, Twedt DC, eds. Kirk's Current Veterinary Therapy, Volume XV. Philadelphia: Saunders Elsevier, 2014; pp 233-237.  
4. Lynn RC, Feldman EC, Nelson RW. Efficacy of microcrystalline desoxycorticosterone pivalate for treatment of hypoadrenocorticism in dogs. DOCP Clinical Study Group. J Am Vet Med Assoc 1993;202:392-396. 
5. Bates JA, Shott S, Schall WD. Lower initial dose desoxycorticosterone pivalate for treatment of canine primary hypoadrenocorticism. Aust Vet J 2013;91:77-82. 
6. Peterson ME: Treating small-breed Addison's dogs with low doses of prednisone or prednisolone. Animal Endocrine Clinic blog, December 14, 2013. 
7. Plumb, DC. Plumb's Veterinary Drug Handbook. Seventh Edition, Wiley-Blackwell. 2011.
8. Melián C, M. Pérez-Alenza, D, Peterson ME. Hyperadrenocorticism in dogs, In: Ettinger SJ (ed): Textbook of Veterinary Internal Medicine: Diseases of the Dog and Cat (Seventh Edition). Philadelphia, Saunders Elsevier, 2010;1816-1840.
9. Hess RS. Insulin resistance in dogs. Vet Clin North Am Small Anim Pract 2010;40:309-316. 
10. Peterson ME. Diagnosis and management of insulin resistance in dogs and cats with diabetes mellitus. Vet Clin North Am Small Anim Pract 1995;25:691-713.  

What's the Best Diet to Fed Dogs with Diabetes?

I'm writing about my dog Minnie, a 7-year old female spayed miniature pinscher (Min Pin). In November of 2012, she was diagnosed with diabetes and started on insulin (Humulin N; NPH insulin). She was very overweight when I adopted her (body weight of 26 pounds) and looked more like a football with legs. After being diagnosed as diabetic, my vet changed her diet to Hills Science Diet w/d. It really helped her lose weight, and now she looks like a Min Pin should look (current weight, 14 pounds).

Despite her body condition normalizing, I am now very concerned about her current health. Her blood sugar levels generally range from 100-120 mg/dl on 7 units of NPH twice daily, but her thirst and urinations remain high. In addition to the polyuria, she now is showing signs of hair loss, muscle weakness, and thinning of the skin. Also, when I feed her, you would think it was her last meal. My thought was that it was from her diet but my vet insists that w/d has everything Minnie needs. 

The vet was concerned that she may have Cushing’s syndrome. We did a screening test for Cushing's syndrome (i.e. a low-dose dexamethasone suppression test), which came back today negative for Cushing’s disease. A test for thyroid function was also normal. I once again asked about the food, which my vet still believes isn’t the cause of her hunger and hair loss.

My question is – Could there be something in W/D that Minnie is allergic to that could be causing some of the same symptoms? Or could it be that she isn’t getting the appropriate nutrition? I’m also wondering what would be another good dog food for diabetic dogs that she might respond to better?

Anyway – thank you for taking the time to read this and I hope you could offer some good advice. 

My Response: 

It's very difficult to attribute all of your dog's clinical signs to the feeding of the Hill's w/d diet. That said, I would change Minnie's diet as the first step in her management.

What's the best diet for canine diabetes?
There is not one type of diet that is recommended for all dogs with diabetes. Diabetic dogs can do well when fed a number of diets as long as they are nutritionally complete and balanced, do not contain simple sugars, are fed at consistent times in consistent amounts, and are palatable to ensure a predictable and consistent appetite. As we all know, it's difficult enough to regulate a diabetic when they are eating consistently well— if they refuse to eat their diet, adequate glucose regulation can become next to impossible.

With any diabetic dog, the most important dietary factor in the diabetic is consistency, so that you can match your insulin dose to the degree of postprandial (after feeding) hyperglycemia. The key to feeding diabetic dogs is to feed the same amount of the same diet at the same time every day!

Feeding diabetic dogs to optimize body weight
In diabetic dogs that are overweight or obese, I always recommend feeding a reduced calorie diet designed to help the dog lose weight. The high fiber diets (such as Hills w/d) are good for this purpose (1-4). So feeding Minnie the w/d when she was grossly obese was a very good idea.

In underweight dogs with diabetes, however, the goal of dietary therapy is the complete opposite. In these thin dogs, our priority is to normalize body weight and restore and preserve muscle mass. These dogs may never regain the weight needed if a food with moderate to high amounts of fiber is fed — they may even continue to progressively lose even more weight. Therefore, these thin to emaciated dogs should be fed a high-quality, higher energy diet that can contain a slightly increased fat content to ensure that they regain their lost body weight (3-5).

Recent studies fail to show a clear-cut clinical benefit of feeding a high-fiber diet over a typical adult maintenance diet with moderate-fiber content to diabetic dogs. In one study, no significant differences in insulin requirements or glycemic control were found in dogs fed a high-fiber, moderate-carbohydrate, moderate-fat diet versus an adult maintenance diet with moderate fiber, lower carbohydrate, and higher fat (5). As expected, weight loss occurred when the dogs were fed the high-fiber diet, whereas body weights were maintained with the moderate-fiber diet. 

Not all diabetic dogs should be automatically fed a high-fiber diet, such as Hills w/d. In your dog, a change in diet to one higher in calories would now be indicated, at least in my opinion.

Cushing's syndrome and diabetes in dogs
I do agree with your veterinarian that the signs of increased hunger, continued polyuria and polyuria (despite good control of the blood glucose values), hair loss, and thin skin all point to hyperadrenocorticism (Cushing's syndrome) (8).  This is a common problem is middle-aged to older dogs, resulting from an excess production of cortisol from the adrenal glands. Secondary diabetes will develop in about 10% of dogs with Cushing's syndrome, and the diabetes is frequently difficult to control (8-10).

The fact that a single test for Cushing's has been negative cannot completely rule out Cushing's syndrome (8,11).  However, the fact that Minnie is showing signs of weight loss cannot be explained by Cushing's, a condition in which weight gain is more common (8-10).

In any case, additional testing of adrenal function should be considered, especially if a diet change hasn't caused a marked improvement within a month or two.

The Bottom Line 

Dogs should never be fed a high-fiber diet just because they have diabetes. Such high-fiber diets are contraindicated in thin or emaciated dogs with diabetes, as well as normal weight dogs that are undergoing unwanted weight loss (5).

Many diabetic dogs do better on maintenance diets containing lower amounts of fiber and carbohydrate and higher amounts of protein. A consistent diet —that is, the type, amount, and time of feeding —is generally much more important in diabetic regulation than any particular fiber content or specific type of diet. Other than that, we want to feed any diabetic dog a diet that will maintain normal body weight.

References: 

1. Nelson R, Duesberg C, Ford S, et al. Effect of dietary insoluble fiber on control of glycemia in dogs with naturally acquired diabetes mellitus. J Am Vet Med Assoc 1998;212:380–386.  
2. Graham PA, Maskell E, Rawlings L. Influence of a high fibre diet on glycaemic control and quality of life in dogs with diabetes mellitus. J Small Anim Pract 2002;43:67–73. 
3. Rucinsky R, Cook A, Haley S, et al. American Animal Hospital Association. AAHA diabetes management guidelines. J Am Anim Hosp Assoc 2010; 46:215-224. 
4. Zicker SC, Nelson RW, Kirk CA, et al. Endocrine Disorders. In: Hand MS, Thatcher CD, Remillard RL, Roudebush R, Novotny, BJ (eds), Small Animal Clinical Nutrition. Mark Morris Institute. 2010; 559-584. 
5. Fleeman LM, Rand JS, Markwell PJ. Lack of advantage of high-fibre, moderate-carbohydrate diets in dogs with stabilised diabetes. J Small Anim Pract 2009;50:604-614. 
6. Rand JS, Farrow HA, Fleeman LM, et al. Diet in the prevention of diabetes and obesity in companion animals. Asia Pac J Clin Nutr 2003;12 Suppl:S6.1 
7. Elliott KF, Rand JS, Fleeman LM, et al. A diet lower in digestible carbohydrate results in lower postprandial glucose concentrations compared with a traditional canine diabetes diet and an adult maintenance diet in healthy dogs. Res Vet Sci 2011;96; 288-95.
8. Melián CM, Pérez-Alenza D, Peterson ME. Hyperadrenocorticism in dogs In: Ettinger SJ, Feldman EC, eds. Textbook of Veterinary Internal Medicine: Diseases of the Dog and Cat. Seventh ed. Philadelphia: Saunders Elsevier, 2010;1816-1840.
9. Peterson ME, Nesbitt GH, Schaer M. Diagnosis and management of concurrent diabetes mellitus and hyperadrenocorticism in thirty dogs. J Am Vet Med Assoc 1981;178:66-69. 
10. Eigenmann JE, Peterson ME. Diabetes mellitus associated with other endocrine disorders. Vet Clin North Am Small Anim Pract 1984;14:837-858. 
11. Peterson ME. Diagnosis of hyperadrenocorticism in dogs. Clin Tech Small Anim Pract 2007;22:2-11. 

Updated Book on Canine and Feline Endocrinology Now Available

BSAVA Manual of Canine and Feline Endocrinology

Edited by:

Carmel T. Mooney

Mark E. Peterson

Building on the success of previous editions, the editors have sought to combine the best of the old with the new in this updated Fourth Edition of the BSAVA Manual of Canine and Feline Endocrinology.

Since publication of the last edition in 2004, there have been many significant advances in clinical endocrinology of companion animals. Several endocrine disorders, such as feline acromegaly and hyperaldosteronism, have risen in importance. The use of novel insulins in diabetic cats and dogs, as well as a wide range of new therapies, have emerged for routine use and are discussed in detail in this Manual. In addition, the genetic risks associated with many endocrine disorders have not been elucidated.

This new edition has been comprehensively updated, while retaining the emphasis on the common problems encountered in investigating and treating endocrine diseases. The Manual is divided into sections covering each endocrine gland and the major and minor endocrine disorders of each species. A separate section deals with relevant presenting complaints in a problem oriented manner.

The fourth edition of this manual provides a ready source of practical information for the practicing veterinarian and will also be useful for students, technicians, and graduates embarking on further specialization.

Click on the link to read a sample chapter from this book, on "Investigation of unstable feline diabetes mellitus."


Table of Contents:

Part 1: Introduction

• Hormone assays and collection of samples
• Principles of interpreting endocrine test results  

Part 2: The Pituitary Gland

• Disorders of vasopressin production
• Pituitary dwarfism
• Acromegaly

Part 3: The Parathyroid Gland

• Hyperparathyroidism
• Hypoparathyroidism

Part 4: The Thyroid Gland

• Canine hypothyroidism
• Canine hyperthyroidism
• Feline hyperthyroidism
• Feline hypothyroidism

Part 5: The Pancreas 

• Canine diabetes mellitus
• Feline diabetes mellitus
• Insulinoma and other gastrointestinal tract tumours 

Part 6: The Adrenal Gland

• Canine hypoadrenocorticism
• Canine hyperadrenocorticism 
• Feline hyperadrenocorticism 
• Feline hypoadrenocorticism 
• Feline hyperaldosteronism

Part 7: Presenting Complaints and Their Investigation

• Investigation of polyuria and polydipsia
• Investigation of hypercalcaemia and hypocalcaemia
• Investigation of unstable canine diabetes mellitus
• Investigation of unstable feline diabetes mellitus
• Ketoacidosis
• Investigation of hypoglycaemia
• Investigation of symmetrical alopecia in dogs
• Investigation of adrenal masses
• Investigation of hyperlipidaemia
• Index

International Contributors:

Amanda K. Boag, UK; Rosario Cerundolo, UK; Dennis J. Chew, USA; David B. Church, UK; Sylvie Daminet, Belgium; Lucy J. Davison, UK; Steve Dodkin, UK; Peter A. Graham, UK; Danièlle Gunn-Moore, UK; Andrea M. Harvey, UK; Michael E. Herrtage, UK; Peter P. Kintzer, USA; Hans S. Kooistra, The Netherlands; Carlos Melian, Spain; Carmel T. Mooney, Republic of Ireland; Raymond F. Nachreiner, USA; Rhett Nichols, USA; Stijn J.M. Niessen, UK; Kostas Papasouliotis, UK; Mark E. Peterson, USA; Ian K. Ramsey, UK; Jacquie Rand, Australia; Nicki Reed, UK; Kent R. Refsal, USA; Patricia A. Schenck, USA; Johan P. Schoeman, South Africa; Robert E. Shiel, Australia; Barbara J. Skelly, UK; Annemarie M.W.Y. Voorbij, The Netherlands.

Purchase the Fourth Edition of the BSAVA Manual of Canine and Feline Endocrinology:

• Amazon
• BSAVA website

Pet Obesity Epidemic Expanding, But Owners in Denial

Big Pets Get Bigger: 

Latest Survey Shows US Dog and Cat Obesity Epidemic Expanding 

The “fat pet gap” continues to widen according to the latest nationwide survey conducted by the Association for Pet Obesity Prevention (APOP). The fifth annual veterinary survey found 53 percent of adult dogs and 55 percent of cats to be classified as overweight or obese by their veterinarian. That equals 88.4 million pets that are too heavy according to veterinarians.

“The most distressing finding in this year’s study was the fact that more pet owners are unaware their pet is overweight.” comments APOP founder Dr. Ernie Ward. “22 percent of dog owners and 15 percent of cat owners characterized their pet as normal weight when it was actually overweight or obese. This is what I refer to as the “fat pet gap” or the normalization of obesity by pet parents. In simplest terms, we’ve made fat pets the new normal.”

 Perhaps even worse was the finding that the number of obese pets, those at least 30 percent above normal weight or a body condition score (BCS) of 5, continues to grow despite 93.4 percent of surveyed pet owners identifying pet obesity as a problem. The study found 24.9 percent of all cats were classified as obese and 21.4 percent of all dogs were obese in 2011. That’s up from 2010 when 21.6 percent of cats and 20.6 percent of dogs were found to be obese. “What this tells us is that more and more of our pets are entering into the highest danger zone for weight-related disorders.” says Ward.

Endocrinologist and fellow APOP Board member Dr. Mark Peterson agrees. “Obesity in dogs and cats is not just the accumulation of large amounts of adipose tissue, but it is associated with important metabolic and hormonal changes in the body. For example, heavy or obese cats are up to four times more likely to develop diabetes as a complication of their obesity. Losing weight can lead to reversal of the diabetic state in some of these obese cats.”

To read or download the complete article and results of the APOP survey, click here.

To learn more about pet obesity or the APOP, go to the Association for Pet Obesity Prevention website.

3 Things You Can Do To Help Your Dog Lose Weight

We are an overweight society and our pets are no different. Over half of American dogs are overweight, and up to 25% are obese.

Dogs with obesity are more prone to a variety of health problems, just like people. These include an increased incidence of diabetes, asthma, and hip and joint problems.

Losing weight can help overweight dogs become healthier and happier. It can also help them to live longer.

Here are some things you can do tomorrow that can help your dog start losing weight.

1. Cut the treats in half. If you must feed treats, cut them in half or give half as many in a day. This can help cut calories. Switching to carrots may help.
2. Exercise your dog more. Ask your vet if your pet is healthy enough to tolerate more exercise. If you play with your dog every day, play a few minutes longer. If you go on a walk, go a little farther. This helps burn calories.
3. Lower the amount of calories your dog consumes each day by changing your dog's food. I like to use diets lower in carbohydrates and higher in protein.

There are several diets formulated for weight loss. Discuss it with your veterinarian to learn more. But remember, whatever diet is chosen, portion control is a big issue.

Although the most common explanation for an overweight pet is simply a lack of exercise and too much to eat. But what if you feed your dog sensibly, exercise adequately, and your dog still has a weight problem?

There could be a number of underlying diseases may be causing your dog to become overweight or obese. Hormonal diseases such as hypothyroidism and Cushing’s syndrome commonly cause weight gain. Steroid pills or tablets with cortisone-like drugs could also be contributing to the obesity.

If these 3 simple hints don't help, ask your veterinarian if an underlying disease could be part of the problem.

Animal Endocrine Clinic March 18 Seminar

We are pleased to announce our second Animal Endocrine Clinic Seminar:

Animal Endocrinology:

Perils and Pitfalls in the Diagnosis and Treatment of Endocrine Diseases 

This seminar will take place on March 18th in Westchester County, NY. AEC Seminars are free and are open to veterinarians and veterinary technicians. The March 18th seminar will deal with several of the most common canine and feline endocrine disorders.

Dr. Mark E. Peterson and Dr. Rhett Nichols will discuss Hyper- and Hypothyroidism, Thyroid and Parathyroid Tumors, Primary Hyperparathyroidism, Idiopathic Hypercalcemia, Diabetes mellitus, Cushing's syndrome, and Hyperaldosteronism.

Further details and the registration form are available here.

Breed Specific Dog Diseases: Smaller Breeds Have Higher Rates of Diabetes And Cushing's Syndrome

University of Georgia researchers, studying more than 75,000 dogs from 82 breeds, have found that the causes of canine deaths vary by breed as well as age (1). The study revealed that congenital diseases, trauma and infection are the most frequent causes of deaths in dogs under 2 years old and that cancer risk peaks at about age 10.

The researchers also determined that bigger dog breeds are more vulnerable to musculoskeletal disease, gastrointestinal disease, and cancer. Smaller breed dogs, on the other hand, are more at risk for endocrine and metabolic diseases such as diabetes mellitus and Cushing's disease (1). 

Rosie, an 11-year old Bichone Frise with both diabetes and Cushing's disease. The photo on the left is before treatment, whereas the photo on the right is after successful treatment of the Cushing's disease and diabetes.

It has long been recognized that there are patterns in the causes of death for our dogs. This study helps owners know what sort of problems to watch out for in their pets. It helps veterinarians focus on the most likely cause of a particular dog’s illness. And most importantly it guides us in identifying specific risks for individual patients and taking action to minimize these and prevent or delay illness and death.

1. Fleming JM, Creevy KE, Promislow DEL. Mortality in North American Dogs from 1984 to 2004: An Investigation into Age-, Size-, and Breed-Related Causes of Death. Journal of Veterinary Internal Medicine 2011; 25: 187-198.

Treating Canine Cushing's Disease: A Success Story

Rosie came to us roughly a year ago exhibiting all of the classic signs of Cushing's disease, which I covered in my last blog post:

• increased thirst and urination
• increased appetite
• excessive panting (see photo on left)
• lethargy
• pot belly appearance (see photo on left)
• weight gain (see photo on left)
• hair loss: hair thinning on trunk, bald tail (see photo on left)

I diagnosed her as having Cushing's disease and prescribed a regimen of trilostane (Vetoryl, Dechra Veterinary Products), given at a dosage of 30 mg twice a day. 

The photo on the right was taken at her one-year check up. As you can see from the photos, she's lost weight (8 pounds) as well as her pot belly. She is much more active and no longer excessively thirsty or panting.

Cushing’s Syndrome: A Common Hormonal Disorder in Dogs

Cushing’s syndrome, also called hyperadrenocorticism, is a disorder which results from the excess production of an adrenal hormone called cortisol. It is a common endocrine disease in middle-aged and older dogs. Miniature Poodles, Dachshunds, Boxers, Boston Terriers, and Beagles are particularly vulnerable.

What causes Cushing's syndrome in dogs?

There are three major causes for Cushing’s syndrome. The most common cause (85–90% of cases) is a small tumor in the pituitary gland. The pituitary tumor produces a hormone (adrenocorticotropic hormone or ACTH) that causes the adrenal gland to grow and oversecrete cortisol.

Less commonly (10–15% of cases), the adrenal glands themselves develop a tumor that secrete cortisol.

A third cause of Cushing's syndrome in dogs results from the long-term use of high doses of corticosteroid drugs such as prednisone or dexamethasone. These steroid drugs are used to decrease inflammation or treat an immune disorder.

What clinical signs do dogs with Cushing's syndrome develop?

Common clinical signs include the following:

• increased thirst and urination
• increased appetite
• excessive panting
• lethargy
• pot belly appearance
• weight gain
• hair loss

How do we diagnose Cushing's disease in dogs?

Diagnosing Cushing’s syndrome can be difficult. Laboratory test results may be inconclusive and dogs suffering from other diseases commonly show false-positive test results for Cushing’s syndrome. (For more information, see this post on my Vet Blog.)

Once we have diagnosed Cushing’s syndrome, the next step is to determine whether the disease stems from a tumor of the pituitary or of the adrenal. This can be done by further endocrine testing or by imaging techniques such as abdominal ultrasound.

How do we treat this problem?

Most dogs with hyperadrenocorticism can be treated with drugs such as mitotane (Lysodren™ or trilostane (Vetoryl™). However, these drugs are most safe and effective when used under the supervision of a veterinarian with much experience their use.

If the dog has a tumor of the adrenal gland, surgical removal is generally the best option. Finally, external radiation therapy can help dogs with pituitary tumors, especially large ones.

Q & A: Why is Cushing's Disease so Prevalent in Dogs, but Not Humans?

Why is Cushing's Disease so prevalent in dogs today but very rare in humans? And why is there such an increase in canine Cushing's patients? 

What does the veterinary world believe to be the root cause of Cushing's? Stress or over-vaccinating of dogs?
Cushing's is a very expensive disease to "live with" - as a result, it would be nice for pet owners to have more substance to work with in terms of understanding what causes this condition in the first place.

My response:

All of your questions are good ones, and I wish I had the answers!  You are correct that Cushing's disease is very common in dogs but extremely rare in people. We do not know why but this has been the case for many years, and it is highly unlikely that stress or over-vaccination plays a role in the canine disease.

Most of these dogs (and people) with Cushing's disease have a small pituitary tumor. In both dogs and people, these pituitary adenomas are monoclonal neoplasms, but why they develop remain unclear.

And finally, you are right about the cost. This is a very expensive disease, both in the diagnosis of the disease as well as the long-term treatment. All of the treatments for Cushing's disease in dogs, which include (1) medical (mitotane or trilostane), (2) surgery hypophysectomy (i.e., removal of the pituitary) or adrenalectomy (i.e., removal of one or both adrenal glands), or (3) pituitary radiation are extremely costly.

Hopefully, we will be able to make some progress in the pathogenesis and develop better and less expensive treatments in the near future.

Obesity in Dogs: Is your Dog Just Eating Too Much, or Is Something Else Wrong?

We are an overweight society and our pets are no different. By far, the most common explanation for an overweight pet is simple: lack of exercise and too much to eat. But what if you feed your dog sensibly, exercise adequately, and your dog still has a weight problem?

There could be a number of reasons your dog is still overweight, including heredity, temperament, and overall activity level. However, a disease may be causing your dog to become overweight or obese.  Hormonal diseases such as hypothyroidism and Cushing’s syndrome commonly cause weight gain. Hormone pills or tablets with cortisone-like drugs could also be contributing to the obesity.

Hypothyroidism is deficient thyroid hormone, and it causes alterations in cellular metabolism that affect the entire body. The dog may not feel like exercising and may gain weight because calories consumed are not matching calories expended. The weight gain then makes the dog feel like exercising even less. Hypothyroidism is usually inherited and a common genetic illness in dogs. Untreated hypothyroidism means a lower quality of life for your dog, but with the proper thyroid supplementation, this condition can be easily controlled, allowing your dog to enjoy a good quality of life.

Cushing’s syndrome (hyperadrenocorticism) is chronic excess of a glucocorticoid hormone, cortisol. This hormone is essential for functions such as maintaining blood glucose levels, metabolizing fats, keeping major organs functioning properly. There are different types of Cushing’s with many symptoms and causes, so it can sometimes be difficult to diagnose. Furthermore, its onset is slow, so its symptoms are often mistaken for signs of age. Cushing’s syndrome can cause reduced activity, change in appetite, and hair loss. Other symptoms include an increased thirst and urination, muscle weakness, and obesity. The cause of the Cushing’s syndrome determines the treatment, which is also influenced by the overall health of the dog.  

Adequate exercise and proper diet are essential for all animals, but if your dog is overweight and you suspect an underlying disease, see a veterinarian for a thorough physical exam including laboratory tests.

Overview of Feline Diabetes

Diabetes mellitus (often called simply diabetes) is a disorder in which blood sugar levels are too high.  Diabetes) is a chronic condition in which a deficiency of the hormone impairs the body's ability to metabolize sugar. It is one of the most common endocrine (hormonal) diseases of cats.

In cats, either a deficiency of insulin or a resistance to insulin causes the diabetes. A number of mechanisms are responsible for decreased insulin secretion or resistance, but most involve destroying islet cells, the cells of the pancreas that produce insulin. Obesity also increases the risk of insulin resistance in cats.

During digestion, carbohydrates are broken down into glucose (a simple sugar), which is absorbed into the bloodstream.  Once in the bloodstream, glucose must enter the body’s cells in order to be used for energy. Insulin signals the body’s cells to absorb glucose from the blood.

A lack of insulin (or insulin resistance) creates two dangerous conditions. First, the body’s cells cannot absorb glucose without insulin; they begin to starve despite the abundant glucose.  Second, because the body’s cells do not absorb glucose, the blood glucose level remains dangerously high. This excess glucose is eventually excreted from the body through the kidneys.  As the glucose passes through the kidneys into the urine, it pulls water with it by diffusion.  This causes increased urination, which leads to increased thirst.

With its cells starving for energy, the body begins to break down its protein, stored starches, and fat. In severe diabetes, muscle is broken down, carbohydrate stores are used up, and weakness and weight loss occur. As fat is broken down, substances called ketones are released into the bloodstream where they can eventually cause diabetic ketoacidosis, a severe complication of unregulated diabetes.

Diabetes can develop in cats of any breed, age or gender. However, older, overweight, and neutered male cats are predisposed to developing this disorder. Diabetes often develops gradually, and many owners may not notice the signs at first.

Diabetes Signs to Watch for in your Cat

• Increased thirst
• Increased frequency of urination
• Weight loss despite a good appetite
• Lethargy
• Poor body condition/poor hair coat
• Rear weakness (associated with diabetic neuropathy)


 Above and below: examples of neuropathy in cats

How is diabetes diagnosed in cats?

Diagnosis of diabetes is based upon the following:
• Complete medical history and thorough physical examination
• Complete blood count (CBC) to check for infection
• Urine analysis to check for glucose and ketones
• Serum chemistry testing to confirm a high blood glucose and to exclude other diseases
• Abdominal X-rays or abdominal ultrasound if complications or concurrent diseases, such as pancreatitis (inflammation of the pancreas), are suspected

Veterinarians diagnose diabetes when cats have high levels of sugar in the blood and urine after fasting.  In cats, the blood sugar level commonly increases under stress, such as when drawing a blood sample, and multiple evaluations may be needed to confirm the diagnosis.

How is diabetes treated in cats?

To successfully manage diabetes, you must understand the disease and take daily care of your cat. Treatment involves a combination of the following:

• Proper weight management
• Diet
• Exercise
• Insulin injections, generally twice daily
• Control of concurrent problems, such as urinary tract infections

Periodic reevaluation is necessary to ensure that the disease is being controlled.  Based on these reevaluations, you may have to change your cat’s treatment regimen over time.

Diabetes Home Care 

At home care involves administering prescribed medications, including insulin, as recommended. If the insulin is prescribed twice daily, try to give it 12 hours apart and at the same time each day. You should also work with your veterinarian to develop a weight management and feeding plan. Stick to regular feeding times.

Familiarize yourself with insulin, insulin syringes, insulin storage, and insulin handling; your veterinarian can help.

Observe your cat's thirst and frequency of urination. If these remain increased, your veterinarian may need to adjust the insulin dosage.

Checking urine or blood sugar concentrations at home can also be very useful in the regulation of your cat’s diabetes.

Insulin overdose may cause low blood glucose, potentially resulting in disorientation, weakness or seizures (convulsions). If you notice any of these symptoms in an otherwise responsive cat, offer food immediately. If the cat is unconscious, Karo® syrup can be applied to the gums. In either case, call your veterinarian as soon as possible.