Thyroid testing in Sloughis

Background: Thyroid hormone concentrations were found to be different in Greyhounds and Whippets compared with nonsight hound dogs. Hypothesis: In Sloughis, thyroid hormone concentration is lower than in nonsight hounds and comparable to Greyhounds. Animals: Fifty-one Sloughis with no evidence of disease and a mean age of 4 years (range, 1-12 years). Methods: Thyroid profiles consisting of total thyroxine (tT4), free thyroxine (fT4), free thyroxine after equilibrium dialysis (fT4 after ED), canine thyroid stimulation hormone (cTSH), and thyroglobulin antibodies as well as CBC and serum biochemistry results of Sloughis were compared with those of normal dogs. In 8 Sloughis, TSH stimulation tests were performed. Results: In Sloughis, tT4 concentrations and fT4 concentrations measured by chemiluminescence were lower than those of controls (1.13 +/- 0.65 mu g/dL compared with 2.9 +/- 0.8 mu g/dL, P < .0001 and 11 +/- 4.3 pmol/L compared with 16.7 +/- 5.2 pmol/L, P < .0001, respectively). Concentrations of fT4 after ED and TSH were increased in Sloughis, when compared with controls (41.3 +/- 26.9 pmol/L compared with 20.98 +/- 10.29 pmol/L, P < .0001 and 0.22 +/- 0.15 pmol/L compared with 0.15 +/- 0.13 pmol/L, P = .0138, respectively). T4 concentration after TSH stimulation increased from 1.5 mu g/dL (range, 0.2-2.7 mu g/dL) to 2.7 mu g/dL (range, 1.2-4.7 mu g/dL); the recommended post-TSH T4 concentration was achieved by only 3 of 8 Sloughis. Hemoconcentration was found in 84.3% and hypoglobulinemia in 80.3%. Conclusions and Clinical Importance: When evaluating Sloughis for hypothyroidism, veterinarians should be aware that these dogs have different thyroid hormone concentrations than nonsight hound dogs.