Dr. Mark Peterson Receives Veterinarian of the Year Award from the Veterinary Medical Association of NYC

 On April 21, 2012, Dr. Mark Peterson was declared the 2012 Veterinarian of the Year by the Veterinary Medical Association of New York City.

This award to given to Dr. Peterson in recognition of his many services to the veterinary professional and his contributions to the Veterinary Medical Association of New York City.

Dr. Mark E. Peterson and Dr. Lisa Esposito

Dr. Mark E. Peterson and Dr. David Wohlstadler

Dr. Peterson speaks at the awards ceremony

Stem Cell Therapy for Thyroid Disease in Cats and Dogs

Questions:
Stem cell therapy is coming into the limelight for animals and humans. I've read of its success treating diabetes, so wonder about the thyroid as well.

Do you have any knowledge of this, or can you point me in a direction to explore? Can stem cell transplantation help cure my older cat with hyperthyroidism? He hates taking the daily methimazole!

My Response:
Stem cells are biological cells found in all multicellular organisms (including humans, dogs, and cats). They are characterized by the ability to renew themselves through mitotic cell division and differentiating into a diverse range of specialized cell types. Stem cells may one day be used to make cells and tissues for therapy of many diseases, including Parkinson's disease, Alzheimer's disease, spinal cord injury, heart disease, diabetes and arthritis (1).

Stem Cells (Picture from: http://biologyblog.edublogs.org/)

Diabetes mellitus is the main endocrine disorder in which research in stem cell therapy has been investigated (2). In many human patients, as in our canine and feline diabetics, diabetes mellitus will frequently reach the stage of life threatening and severely disabling complications, which cannot be controlled by insulin alone.

Several other hormone deficiency disorders (hypothyroidism, Addison's disease) could potentially be helped by stem cell transplantation However, it is relatively easy to provide hormone replacement for these disorders, so there is not a huge incentive to use stem cell therapy for these diseases.

There is ongoing research concerning stem cell therapy for thyroid disease in people (3-6), but I do not know of anyone working on stem cell therapy for thyroid disease in cats. However, notice that — even in people — they are concentrating on stem cell therapy for thyroid cancer (4,6).  Again, it's relatively cheap and easy to provide thyroid supplements for hypothyroidism. Hyperthyroidism is relatively easy to cure with radioiodine (7-10), so investigators aren't overly concerned with stem cell transplantation for that condition.

References:

1. Sharma S, Vyas G, Gawarikar SB, et al. Stem cell transplantation: brief review and current status. Journal of the Indian Medical Association 2011;109:570-574, 579-581. 
2. Fiorina P, Voltarelli J, Zavazava N. Immunological applications of stem cells in type 1 diabetes. Endocrine Reviews 2011;32:725-754.
3. Lin RY. New insights into thyroid stem cells. Thyroid 2007;17:1019-1023.
4. Thomas D, Friedman S, Lin RY. Thyroid stem cells: lessons from normal development and thyroid cancer. Endocrine-Related Cancer 2008;15:51-58. 
5. Davies TF, Latif R, Minsky NC, et al. Clinical review: The emerging cell biology of thyroid stem cells. The Journal of Clinical Endocrinology and Metabolism 2011;96:2692-2702.
6. Lin RY. Thyroid cancer stem cells. Nature Reviews: Endocrinology 2011;7:609-616.
7. Radioiodine therapy for hyperthyroidism. Drug and Therapeutics Bulletin 2006;44:44-48. 
8. Franklyn JA, Boelaert K. Thyrotoxicosis. Lancet 2012;379:1155-1166.
9. Peterson ME: Radioiodine treatment for hyperthyroidism. Clinical Techniques in Small Animal Practice 2006;21:34-39.
10. Peterson ME, Broome MR: Radioiodine for hyperthyroidism. In: Bonagura JD, Twedt DC (eds): Current Veterinary Therapy XV. Philadelphia, Saunders Elsevier, 2012, in press.

Pet Obesity: No Laughing Matter

As the number of Americans who are overweight has grown, studies show that the same statistics apply to our companion animals. About half of all dogs and cats in American homes are overweight or obese, up slightly from 2010, according to a recent study by the Association for Pet Obesity Prevention.

And although owners may think their pudgy dog or cat is cute, all that extra weight spells trouble the some 85 million U.S. pets who are considered overweight.

And many pet owners are finding that the extra pounds on a pudgy cat or dog can lead to severe secondary health problems. Just as diabetes, joint problems, and heart disease are more common in people who are obese, these diseases also are more common in overweight animals. The average cost of veterinary care for a diabetic dog or cat in 2011 was more than $900, according one pet insurance company. Treatment for arthritis and cruciate ligament tears in dogs, which can be caused by the strain of an overweight frame that weakens joints, cost pet owners an average of $2,000.

Last week, an interesting article the cost of pet obesity was published in the Wellness section of the New York Times. To read the complete article, entitled "Paying the Price of a Fat Pet," click this link.

• O'Connor, AO. Paying the Price of a Fat Pet. Well Pet Blog, The New York Times. April 20, 2012. 

Do Cats with Hyperthyroidism in Cats Ever Go Into Spontaneous Remission?

Question:
Gracie, our 8-year old, spayed female DSH has just been diagnosed with hyperthyroidism, based on the finding of a high serum T4 value (12.4 μg/dl; reference range, 1-4.7 μg/dl). We only did her blood work in anticipation of a dental cleaning, and are shocked by this news. 

Gracie has no symptoms whatsoever of this disorder. She eats and drinks a normal amount; her diet has been mostly high quality, grain-free dry food (she never liked or ate canned until very recently, also grain-free).  She has shown slight weight loss, but only because she was overweight and we were controlling her intake — trying to get her to loose weight.  Her behavior and attitude are positive; no change from before. Her coat, skin, and eyes all fine. Hydration is fine. Digestion and bowels fine (no vomiting, no diarrhea). Just some bad breath (hence the dental). 

Our vet feels nothing upon palpation of her thyroid. If anything, she may have a slightly high heart rate (212 beats per minute taken at vet's...possibly nerves), but her blood pressure was fine (averaged 128/77 out of 5 readings). 

We had the T4 test run a second time at a different lab and it came back high again at 11.2 μg/dl.

My question to you is this....in your years of experience with hyperthyroidism, has there ever been an occasion when the T4 values have receded on their own, without medication or irradiation? I ask this because Gracie is so young and has no symptoms. 

I would not want to irradiate her thyroid if there is any possibility of this being a "passing phase" in her life. However, I am quite aware of the dangers and complications of hyperthyroidism, and do not want to play around with her health. With everything else so "normal," I would be willing to wait a month or two and recheck her if you think there's any hope in doing so. Are you aware of any current research indicating that T4 numbers can fluctuate in a young cat? More than any other factor, it is her young age that makes me question whether these T4 readings are permanent. 

My Response:
No, I've never seen a hyperthyroid cat go into remission. Cats with hyperthyroidism all have one or more benign thyroid nodules, generally benign tumors or adenomas (see Figure below). These thyroid tumors will not go away spontaneously once they have formed (1-4). The only way to cure this disease is by use of radioiodine (I-131) to irradiate the adenomatous thyroid nodule(s), or by use of surgery to remove the abnormal thyroid gland (1-6).

Palpating a large thyroid nodule (adenoma) in a hyperthyroid cat

It's not unusual for middle-aged cats (like Gracie) to be relatively asymptomatic for quite a while during the early stages of the disease, as the problem is just starting to manifest itself. Geriatric cats aren't able to compensate as well and they show more obvious signs earlier in the course of the disease.

It's sounds like you think that a cat of 8-year's of age is too young to develop hyperthyroidism. But we do occasionally see cats as young as 6 years of age, and very rarely, even as young as a year or two (1-4,7).

That all said, I'm bothered that your veterinarian is not able to palpate an enlarged thyroid tumor with a T4 value that is clearly quite high. You might want to have another veterinarian palpate Gracie's neck to see if they can identify one or more thyroid nodules. If they cannot and the serum T4 remains high, it would be very useful to do thyroid scintigraphy (ie, a thyroid scan) to document the presence or absence of a thyroid tumor. Thyroid scintigraphy is the most sensitive diagnostic test we have to confirm the presence of hyperthyroidism in cats (8-10), and we use this procedure routinely in my practice.

You certainly could monitor the T4 value again in a month or two, especially since Gracie is stable. But it certainly does sound like she has hyperthyroidism and will need to be treated at some time in the near future.

References:

1. Peterson ME: Hyperthyroidism, In: Ettinger SJ, Feldman EC (eds): Textbook of Veterinary Internal Medicine: Diseases of the Dog and Cat (Fifth Edition). Philadelphia, WB Saunders Co. 2000; pp 1400-1419.
2. Peterson ME: Hyperthyroidism in cats. In: Melian C (ed): Manual de Endocrinología en Pequeños Animales (Manual of Small Animal Endocrinology). Multimedica, Barcelona, Spain, 2008, pp 127-168.
3. Baral R, Peterson ME. Thyroid gland disorders. In: Little, S.E. (ed), The Cat: Clinical Medicine and Management. Philadelphia, Elsevier Saunders 2012; 571-592. 
4. 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. 
5. Peterson ME: Radioiodine treatment for hyperthyroidism. Clinical Techniques in Small Animal Practice 2006;21:34-39.
6. Peterson ME, Broome MR: Radioiodine for hyperthyroidism. In: Bonagura JD, Twedt DC (eds): Current Veterinary Therapy XV. Philadelphia, Saunders Elsevier, 2012, in press.
7. Broussard JD, Peterson ME, Fox PR. Changes in clinical and laboratory findings in cats with hyperthyroidism from 1983 to 1993. Journal of the American Veterinary Medical Association 1995;206:302-305. 
8. Broome MR. Thyroid scintigraphy in hyperthyroidism. Clinical Techniques in Small Animal Practice 2006; 21:10-16. 
9. Daniel GB, Brawnier WR. Thyroid scintigraphy In: Daniel GB, Berry CR, eds. Textbook of Veterinary Nuclear Medicine. 2nd ed. Harrisburg, PA: American College of Veterinary Radiology, 2006;181-199.
10. Peterson ME, Broome MR. Thyroid scintigraphic findings in 917 cats with hyperthyroidism. Journal of Veterinary Internal Medicine 2012; in press.

Can Chronic Stress and Cortisol Resistance Make Your Pet Sick?

It is well known that chronic stress and illness are related. For example, psychological stress in humans raises the risk of heart disease, colds and flu. And chronic stress in animals is also well known to lead to diseases such as upper respiratory or lower urinary tract infections.

But how does such stress lead to illness? New research published recently in the Proceedings of the National Academy of Sciences (1) found that the adrenal hormone cortisol plays a critical role in the illness caused by stress.

Released in greater amounts in times of stress, cortisol helps suppress the body’s immune response to infections, suppressing inflammation responses like coughing, sneezing, or fever. But when levels of cortisol remain high, the body may become less sensitive to it — a condition called cortisol or glucocorticoid "resistance."

So in other words, when we are stressed out, we overproduce cortisol, making our immune system incapable of turning "off" the inflammation response. If we're exposed to a virus while we are also dealing with chronic stress, the study found that we'd also be much more likely to get sick and suffer from more intense symptoms (1).

In other words, many of the symptoms of a cold, for example, are not caused directly by the virus, but rather, they're caused by the inflammatory response to the infection. We want the body to produce enough of inflammation to fight off the infection, but not so much that we experience worsened symptoms.

The Bottom Line:
Chronic stress may raise the risk of sickness by creating a state of resistance to the hormone cortisol, which, in turn, interferes with appropriate regulation of inflammation.  Because inflammation plays an important role in the onset and progression of a wide range of diseases, this model may have broad implications for understanding the role of stress in health.

Although we do no know if the same phenomenon of stress-induced cortisol resistance exists in animals, it is certainly possible. We certainly do know that physical and psychological stress can induce disease in domestic animals (2-4).

References:

1. Cohen S, Janicki-Deverts D, Doyle WJ, et al.  Chronic stress, glucocorticoid receptor resistance, inflammation, and disease risk.  Proceedings of the National Academy of Sciences (PNAS) 2012; ,doi:10.1073/pnas.1118355109.
2. Westropp JL, Kass PH, Buffington CA. Evaluation of the effects of stress in cats with idiopathic cystitis. American Journal of Veterinary Research 2006;67:731-6.
3. McCobb EC, Patronek GJ, Marder A, et al. Assessment of stress levels among cats in four animal shelters. Journal of the American Veterinary Medical Association 2005;226:548-555.
4. Stephens DB. Stress and its measurement in domestic animals: a review of behavioral and physiological studies under field and laboratory situations. Advanced in Veterinary Science and Comparative Medicine 1980;24:179-210.

Proper Nutrition and Lifestyle Essential for Cats

Cats have lived on the outer edges of human society for many thousands of years. However, domestication has changed cats relatively little. Diet options for cats in the wild have included consumption of small mammals, birds, and insects. These are meat or protein-based diets that contain little carbohydrate.

Cats, as a species, are strictly carnivorous. In many societies, they have been removed from their former free-roaming, active existence to a captive, indoor, sedentary one. They have also gone from consuming frequent, small meals of animals they could catch and kill to consuming prepared diets of human choosing.

Proper nutrition plays a key role in the prevention and management of many common feline endocrine disorders, including obesity, diabetes mellitus, and hyperthyroidism.

For more information, see this interesting blog post published last week in Cat Health News from the Winn Feline Foundation entitled, Cats: nutrition and lifestyle choices.

Related articles: 

• Zoran DL and Buffington CAT. 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. 
• Zoran D. The carnivore connection to nutrition in cats. Journal of the American Veterinary Medical Association 2002; 221: 1559-67.

Steve Dale Interviews Dr. Peterson About Treatment Options for Feline Hyperthyroidism

Dr. Mark Peterson was recently interviewed by Steve Dale about the options available for treating feline hyperthyroidism.

You may click through to subscribe to the Animal Endocrine YouTube Channel, as well as Steve Dale's YouTube Channel, to keep on top of new video uploads. Dr. Peterson and the Animal Endocrine clinic can also be followed on our Animal Endocrine blog, our blog for vets, our website, on Facebook and on Twitter.