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

BACKGROUND

Hypercalcemia associated with granulomatous disease in dogs can present a diagnostic challenge.

HYPOTHESIS/

OBJECTIVES

Excessive endogenous, extrarenal calcitriol production is a potential mechanism of ionized hypercalcemia in dogs with granulomatous skin conditions.

ANIMALS: Hypercalcemic client-owned dogs (n = 7) with chronic skin disease seen in general and specialty practices with calcium profiles submitted to a university veterinary diagnostic laboratory by the attending clinician.

METHODS

Descriptive case series reporting clinical presentation, laboratory findings, treatment, and outcome of 7 hypercalcemic dogs with dermatopathies of varying etiology.

RESULTS

Panniculitis was confirmed histologically in 5 dogs (idiopathic, n = 4; presumed bacterial, n = 1). The other 2 dogs had severe generalized demodicosis (n = 1) and demodectic/sarcoptic mange with superficial and deep pyoderma (n = 1). Initial testing showed clinically relevant parathyroid-independent ionized hypercalcemia, undetectable parathyroid hormone-related protein concentration, and 25-hydroxyvitamin D concentration close to or below the lower reference limit in all dogs. Calcitriol concentration was above reference interval in 6 dogs at initial testing, and near the upper reference limit in 1 dog 29 days after presentation. In all cases, normalization of calcium and vitamin D homeostasis paralleled clinical improvement with appropriate therapy for the underlying skin condition.

CONCLUSIONS AND CLINICAL

IMPORTANCE

Ionized hypercalcemia apparently mediated by excessive extrarenal calcitriol production can be seen in dogs with granulomatous skin disease. Calcitriol measurement should be included with other calcium-related testing in the workup of unexplained hypercalcemia with concurrent chronic skin disease.