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Originally Posted by bchgirl  A friend's yorkie was recently diagnosed with hypothyroidism. There's a more detailed test available than just the panel and it can also determine whether or not the thyroid condition is genetic or not. |
The recommended blood test for screening purposes is the total T4. This test is indicated for dogs that have findings suggestive of hypothyroidism on physical examination. A normal T4 is fairly conclusive evidence that the dog does not have hypothyroidism. However, a low-normal or below normal level does not mean the dog is hypothyroid, because concentrations below normal are common for many reasons other than hypothyroidism.
To avoid overdiagnosing and overtreating the disease, it is important to confirm the significance of a low T4 using a more accurate thyroid function test, such as the FT4, by equilibrium dialysis. Other blood tests also are available for diagnosing hypothyroidism. One is an assay for thyroglobulin autoantibodies; these autoantibodies are present in about 50 percent of cases of autoimmune thyroiditis. This test must be sent to a special laboratory for analysis.