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Usefulness of scintigraphy in determining thyroid status in dogs
R. E. Shiel, M. Pinilla, H. McAllister, C. T. Mooney
IN dogs, hypothyroidism is most commonly diagnosed by measuring the serum concentrations of total or free thyroxine (T4) and canine thyroid-stimulating hormone (cTSH). In some cases, additional diagnostic tests are required. One option is scintigraphy, which involves measuring thyroidal uptake of a radionuclide as an indicator of thyroid function. This study assessed the value of technetium scintigraphy as a diagnostic test in dogs referred for investigation of thyroid dysfunction.
Twenty-one dogs showing signs compatible with hypothyroidism were investigated. The serum concentrations of total and free T4, cTSH and triiodothyronine (T3), and antibodies to thyroid hormones, were measured. The thyroid was examined by ultrasonography. Scintigraphy was performed in sedated dogs by injecting pertechnetate into the right cephalic vein and then acquiring images using a gamma camera. The scintigraphic images were assessed and the technetium thyroidal uptake (TCTU) calculated. The dogs were classified on the basis of the TCTU as euthyroid, equivocal or hypothyroid.
The total T4, free T4 and T3 concentrations were below the reference range in eight, seven and nine dogs, respectively; three dogs had autoantibodies to thyroid hormones …