Suspected calcitriol‐mediated hypercalcaemia and postmortem diagnosis of histiocytic sarcoma in a dog

Abstract This report describes a case of refractory ionised hypercalcaemia, of 12 months duration, in an 11‐year‐old, male, neutered beagle diagnosed with metastatic histiocytic sarcoma at postmortem examination. In this case, the parathyroid hormone levels were at the lower end of the reference interval, the parathyroid hormone‐related peptide was unmeasurable/Low, and 25‐hydroxycholcalciferol was within reference range, while calcitriol levels were inappropriately high (although at the top of reference range), suggesting that the ionised hypercalcaemia was mediated via excessive calcitriol secretion.