Thyroid Hormone Concentrations in Healthy Adult Dogs in Yola, Adamawa State

Thyroid hormones, particularly triiodothyronine and thyroxine, regulate metabolic rate, reproductive function, and cardiovascular homeostasis in dogs. Hypothyroidism is one of the most commonly diagnosed endocrine disorders in canine practice globally, and its diagnosis depends on comparing individual patient values against established reference intervals. Reference intervals for thyroid hormones in dogs in Nigerian tropical environments, where temperature and nutrition differ markedly from temperate settings, have not been defined. This study measured serum total triiodothyronine, total thyroxine, and free thyroxine concentrations in 60 apparently healthy adult mixed-breed dogs in Yola, Adamawa State, North East Nigeria. Dogs were examined clinically to exclude systemic illness, and body condition score was recorded. Blood was collected from the cephalic vein, and serum hormone concentrations were quantified using a validated enzyme-linked immunosorbent assay. Mean total thyroxine was 22.3 nmol/L with a 95 percent reference interval of 12.8 to 39.1 nmol/L. Mean free thyroxine was 16.7 pmol/L. Total triiodothyronine mean was 1.4 nmol/L. Age was inversely correlated with thyroxine concentrations in dogs above seven years. Body condition score showed a positive correlation with total thyroxine. These reference data provide a baseline for interpreting thyroid function in dogs in Yola and the North East, supporting more accurate clinical diagnosis of thyroid disorders in canine patients under Nigerian conditions. Keywords: thyroid hormones, dogs, thyroxine, reference interval, Yola.