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Yep. Not only do I find this disease of slow-metabolism to be one many of us humans wish we had (especially when at a loss to explain why we gained so much weight over the holidays)—hypothyroidism is an illness pet owners increasingly want their overweight pets tested for.

Wielding the “I only feed this much” hammer I’m so commonly hit with, they want Fido or Fluffy screened for the disease well-known to cause weight gain, skin problems, hair loss, inactivity, a sub-normal appetite and maybe even behavioral problems.

As in…“He’s got to be hypothyroid, Doc! How else could he get soooo fat. I mean, I only feed him this much.” (Now make the universal hand signal for about half a cup and you’ll get the picture.)

And while Fido may well be hypothyroid, most overweight and obese pets are not. In fact, cats hardly ever get hypothyroidism—rather, they tend to get hyperthyroidism, the speedy metabolism disease, typically with advancing age. The underactive thyroid of hypothyroidism is mostly a middle-aged dog disease—as well as one we humans have long recognized among our own species.

It’s true that our pets are growing more obese every year. And it’s also true that hypothyroidism is statistically on the rise in our dog populations. Researchers, however, submit that increased screening and overdiagnosis (by means of inadequate or insufficient testing), are hugely on the rise, too, likely inflating the numbers of affected dogs relative to earlier years.

If my clients’ express requests for thyroid testing are any measure, I can see why researchers might pose this concern when evaluating the true prevalence of the disease.

Thyroid hormone testing (the standard T4) has now become part of many vets’ core screens. Anytime we see this hormone looking low or low-ish, we tend to take note, especially in dogs with clinical signs like obesity. But thyroid hormone levels go up and down throughout the day. That’s why one single test is considered inadequate to establish a diagnosis.

More advanced testing is often necessary to look at different thyroid-related levels before making a diagnosis and treating the disease. Many specialists even suggest that the T4 is a more misleading metric than we’d previously thought. Instead, they want us to look at “free T4” (the unbound version of thyroid hormone) and TSH (thyroid stimulating hormone).

But those tests aren’t in our standard screens, which often means owners have to bring their dogs back for another blood draw—or change our standard protocols in favor of more expensive tests ($75 instead of $20). Many owners won’t do this. They’d rather have you prescribe a drug and be done with it, the way we did in years past.

Which brings me to treatment of the condition: It’s fairly simple. Give a pill a couple of times a day—a thyroid hormone replacement with zero side effects. Zero, that is, as long as you have the right diagnosis. If you’re wrong and you prescribe the drug, long-term effects can be serious, especially with advancing age as organs and tissues get over-stimulated with an overabundance of thyroid hormone.

Nonetheless, it’s still the disease we wish for to explain away the obesity we’re too often convinced has nothing to do with our dogs’ normal metabolism, diet, innate indolence, osteoarthritis or lack of exercise.

It’s not shocking, really, that so many pet owners want to find problems that are easily solved with pills and quick fixes. And it’s not surprising that vets might want to please their clients by indulging their hopes (I’m guilty as charged).

Despite our tendency to want to solve problems and gratify, its our responsibility as health professionals to get better at screening our patients. In the long run it helps us not at all to cave to our clients’ desires at the expense of our patients’ health.

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