Endogenous calcitriol production and ionized hypercalcemia in 7 dogs with chronic dermatopathy of infectious and noninfectious etiology (2016-2024).

Measure calcitriol in hypercalcemic dogs with granulomatous skin disease for accurate diagnosis.

This descriptive case series describes 7 hypercalcemic dogs with chronic dermatopathies presenting with ionized hypercalcemia mediated by extrarenal calcitriol production. Five dogs had histologically confirmed panniculitis (4 idiopathic, 1 presumed bacterial), while 2 had severe demodicosis with concurrent mange and pyoderma. Initial laboratory evaluation revealed parathyroid-independent ionized hypercalcemia, suppressed PTHrP concentrations, and low to low-normal 25-hydroxyvitamin D levels in all cases. Six dogs demonstrated elevated calcitriol concentrations at presentation, with the seventh showing near-upper reference limit values 29 days later. Significantly, normalization of calcium and vitamin D homeostasis correlated with clinical improvement following appropriate treatment of underlying skin conditions. This report establishes that excessive extrarenal calcitriol production represents a clinically relevant mechanism of hypercalcemia in granulomatous dermatopathies. The authors recommend including calcitriol measurement in comprehensive metabolic workups for unexplained hypercalcemia concurrent with chronic skin disease, improving diagnostic accuracy and understanding of pathophysiology in these cases.

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