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 Pythium insidiosum. 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.