One thing that turned up on Rosie’s blood-work was something that I had suspected: Rosie was hypothyroid.

The thyroid, a bi-lobed gland in the neck, produces thyroid hormone. Thyroid hormone functions as a master controller of the body’s metabolic system and there is no tissue or organ system in the body that is not affected by thyroid hormone.

It seems that such an important hormone that does so much would show obvious symptoms when not present in the correct amounts. But the gradual onset and widespread effects, make it difficult to detect initially.

Hypothyroidism, producing too little thyroid hormone, can masquerade as old age in animals. A hypothyroid dog is often lethargic, mentally dull, tends to gain weight, fatigues easily, and has poor cold tolerance. Essentially, they turn into slow motion, heat-seeking missiles, always looking for a warm place to sleep. Classic hypothyroid changes in dogs can be seen in the coat, including hair loss, a dry scaly coat, and recurrent skin infections. Behavioral changes may include increased irritability (“crabby”) or less enthusiasm, which may be described as “sad” as my friend Melodie noticed in Rosie.

One would think that a disease with such far-reaching effects would be easy to recognize and diagnose. But sadly, this is not the case. Accurately diagnosing hypothyroidism can be a complex combination of observing clinical signs and sometimes several laboratory tests (luckily, with Rosie we found it easily). Sometimes, if the clinical picture and test results are ambiguous or don’t agree, the diagnosis has to be made by doing a short trial therapy and looking at the response.

There is controversy about the prevalence as well. Many veterinarians believe that hypothyroidism in dogs is over-diagnosed; while others believe that it is under-diagnosed. In all reality, probably both viewpoints are accurate; there are likely hypothyroid dogs who are not recognized and diagnosed, while there are also cases of dogs who were not, it turned out, actually hypothyroid.

A majority of hypothyroid cases in mature dogs is a result of deterioration of the thyroid gland itself, making it unable to provide the body with the thyroid hormones it needs. The cause of this is unknown. What is known, is that life-long, thyroid supplementation will be necessary. A daily dose of the correct amount of supplemental thyroid (as determined by your veterinarian) will keep hypothyroid dogs healthy and happy for years.

I am grateful to my friend for alerting me to a problem that was right under my nose when I had on the blinders of familiarity. Likely we would have caught this eventually, but for Rosie’s sake, sooner was better than later.