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THYROID SURVEY

THYROID STUDY COMPLETED
Helen Hamilton, DVM
Health Committee Chair

Project: Establishing Thyroid Normals in the Greyhound breed
Researcher:  Dr. Ray Nachinder – Michigan State University,

The study of Greyhounds and Thyroid Testing has been competed and the results reported in an article written by Dr. Marcus Rick and published in the GCA Fall 2005 Newsletter.  Of one hundred samples that were collected, 98 were analyzed statistically to establish a reference range of thyroid test results in the Greyhound.  The majority of the samples were from AKC registered Greyhounds, seven were from NGA dogs.  The results were then compared graphically with the reference range for the general dog population used at Michigan State University and the result ranges from three previous studies by other researchers.

Dr. Rick states “Overall it can be seen that the reference range of Greyhounds is considerably less than that of the general canine reference range.”  In very short summary he concludes:

1. Overall, hypothyroidism is very unlikely in the Greyhound, however well documented cases exist.
2. If either total T4 of free T4 by dialysis are detectable with the currently available assays (GT 6nmol/L, GT 2pmol/L, respectively) it is very likely that your Greyhound is NOT hypothyroid.
3. Lymphocytic thyroiditis is unlikely as well.  Of 1,409 Greyhound samples received at Michigan State University, 2 % were TgAA positive compared with 10 % of 143,800 dogs of the general dog population.  Of these 1,409, only 43 (3%) had thyroid results including elevated TSH consistent with hypothyroidism compared to 8 % of the general 143,800 samples.
4. Diagnosing hypothyroidism might be difficult due to decreased reference values that, in many cases, are below the detection limit of currently available assays.
5. Greyhound-specific complaints, including bald thigh syndrome, poor racing performance, and infertility do not have an association to thyroid hormone concentrations.  Supplementing these animals with thyroxine is not recommended.