Why Your Dog’s Anti-Thyroid Antibody Test Is Positive

Why Your Dog’s Anti-Thyroid Antibody Test Is Positive

Ron Hines DVM PhD

See What Normal Blood & Urine Values Are

The Causes Of Most Abnormal Blood  & Urine Tests

See How Tests Are Grouped

Anti-Thyroid Antibodies In Your Pet’s Blood

Your veterinarian can identify most hypothyroid dogs (and even the much rarer hypothyroid cat) with a one to three tests,  Free T4, T3, and, when required, a TSH stimulation test.

However, a few cases that your veterinarian sees have all the common symptoms of hypothyroidism – but they can’t seem to be confirmed hypothyroid with those first three tests alone. Other dogs are checked for the presence of anti-thyroid antibodies because they haven’t responded satisfactorily to a standard veterinary dose of thyroid medication.

In some of those dogs – particularly golden retrievers, Shetland and Old English sheepdogs, and doberman pinschers – anti-thyroid antibodies that destroy the dog’s own thyroid hormones as well as thyroid supplements are to blame. The anti-thyroid antibody test can help identify those dogs. 

In another situation, potential breeding dogs can be screened for genetic susceptibility to this form of hypothyroidism. Elevated anti-thyroid antibody often appears in dogs before actual disease becomes evident and before T3 and T4 levels become subnormal. Hypothyroidism is extremely rare in cats so I can not tell you much about the test’s use in felines.

Complementary Tests:

Most likely, a complete thyroid panel would have been run before an anti-thyroid antibody test was suggested. An exception would be dogs being screened for a tendency toward hypothyroidism.


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