EXPRESS: Severe Hypercalcemia in a Cat Following Treatment with Antibiotic Impregnated Calcium Sulfate Carrier Material for Chronic Pyogranulomatous Panniculitis

A three year old female spayed Domestic Shorthair with seven months of pyogranulomatous panniculitis was referred following culture isolation of Actinomyces species. Despite initial improvement, clinical resolution was not achieved with the dosage and duration of clindamycin therapy previously reported as adequate for actinomycosis. Surgical resection with antibiotic impregnated calcium sulfate carrier material for local delivery of ampicillin-sulbactam was pursued. The patient developed severe hypercalcemia (21.6 mg/dL; reference interval 7.8-11.3 mg/dL) following surgery, resolving after seven days of 0.9% saline diuresis and bisphosphonate therapy. Mycobacterium abscessus was isolated from tissue culture. Following five months of clarithromycin therapy, clinical resolution of mycobacteriosis panniculitis was achieved. This case documents the management of a potential complication of calcium sulfate carrier material, a local antibiotic delivery material that is increasingly used for chronic soft and osseous tissue infection management. This case documents the management of a medically refractory case of infectious feline panniculitis specifically as a result of complex bacterial culture interpretation specific to rapid-growning non-tuberculosis mycobacterium.