Hypercalcaemia in a dog with hypothyroidism

A 5‐year‐old, entire, female Greenland dog was presented with polyuria and polydipsia. A mildly increased circulating concentration of ionised calcium, mild non‐regenerative anaemia, mild hypercholesterolemia and mild increases in liver enzyme activity were detected. Parathyroid hormone, plasma parathyroid hormone‐related protein and vitamin D were analysed in a blood sample, with all results below the lower limit of the reference range. Further investigation with abdominal ultrasonography, fine‐needle aspiration for cytology of the liver and spleen, thoracic radiography, adrenocorticotropic hormone‐stimulation and serum protein electrophoresis could not detect any disease. During the next months, the dog developed coat changes that clinically corresponded to an endocrinopathy. Analysis of thyroxine and thyroid‐stimulating hormone was performed. Thyroxine was less than 6 nmol/L and thyroid‐stimulating hormone was 1.5 µg/L, which indicated primary hypothyroidism. Treatment with l‐thyroxine resulted in normalisation of the hypercalcaemia. Moreover, the polyuria and alopecia resolved.