Vitamin D‐Mediated Hypercalcemia in a Dog With Putative Cutaneous Pythiosis

A 12-month-old dog was diagnosed with cutaneous pythiosis after presenting with a nonhealing metatarsal wound, an inguinal mass, and regional lymphadenopathy. Both cytology of the abnormal lymph nodes and histopathology of the inguinal mass showed granulomatous inflammation. ELISA serology was positive for <i>Pythium insidiosum.</i> The dog developed hypercalcemia secondary to excessive vitamin D production. This conclusion was based on the combination of hyperphosphatemia, suppressed parathyroid hormone, suppressed 25-hydroxyvitamin D level, and a calcitriol level at the high end of the reference interval. This case report describes the protracted diagnosis of vitamin D-mediated hypercalcemia in conjunction with cutaneous pythiosis infection. As this was not a known risk in pythiosis cases, delayed diagnosis and treatment of hypercalcemia, along with delayed diagnosis of the pythiosis infection and use of compounded itraconazole, contributed to a poor outcome.