Disseminated abdominal actinomycosis with urinary tract involvement in a dog

Abstract

A 2.5-year-old, female, neutered, Shih Tzu presented with a 4-month history of pollakiuria, abdominal pain and lethargy. Physical examination identified abdominal discomfort and multiple palpable abdominal masses. Abdominal computed tomography confirmed multifocal masses, one of which was adhered to the urinary bladder wall, while another was causing right-sided ureteral obstruction and hydronephrosis. The dog underwent exploratory laparotomy to perform partial excision of some of the masses and also to acquire samples for histopathology and culture. Histopathology documented severe pyogranulomatous peritonitis and steatitis, while tissue culture yielded Actinomyces viscosus. The dog was treated with amoxicillin/clavulanic acid, based on culture and sensitivity testing, for 7 consecutive months, 1 month beyond resolution of ultrasonographic evidence of disease. There were no signs of relapse 6 months after discontinuation of treatment. This is a unique case report of canine disseminated abdominal actinomycosis demonstrating successful long-term management following treatment with surgery and antimicrobial therapy.