Successful treatment of peritoneal nocardiosis caused by Nocardia paucivorans in a dog

Authors: Mund GM, Haussler TC, Aurich SH, Ewers C, Thiel C
Publication: New Zealand Veterinary Journal, Volume 69, Issue 6, pp 355-360, Nov 2021
Publisher: Taylor and Francis

Animal type: Dog
Article class: Clinical Communication

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Abstract:

Case history: A 7-year-old neutered female Labrador Retriever from Hesse (Germany) was referred for evaluation of peritoneal nodular masses identified by the referring veterinarian during an investigation for a 2-month history of lethargy.

Clinical findings and treatment: Ultrasonographic examination of the abdomen showed multiple cavernous nodules in the intra-abdominal fat and greater omentum surrounded by free fluid. These findings were suspicious of steatitis and fatty tissue necrosis in the cranial abdomen. Cytologic and microbiological analysis of fine-needle aspirates of the fatty tissue and abdominal fluid revealed septic pyogranulomatous inflammation caused by Nocardia paucivorans. The septic abdomen indicated surgical management was appropriate and a celiotomy was performed, which revealed an inflammed mass attached by fibrous tissue to the spleen, stomach and liver. All abnormal tissue including parts of the greater omentum and the spleen, were removed and samples taken for histopathology and microbial culture. Following surgery, the dog was treated with amoxicillin/clavulanic acid. After initially improving, the dog's condition deteriorated 3 months later. Based on ultrasonographic and cytologic findings, and bacterial culture, recurrence of peritoneal nocardiosis was confirmed. In a second celiotomy, multiple inflammatory mass lesions inflammed masses in the remaining greater omentum were removed. After surgery, antimicrobial therapy was changed to trimethoprim/sulfamethoxazole for a 10-month period. No recurrence of clinical signs was reported 6, 12 and 27 months after the initial surgery.

Diagnosis: Peritonitis caused by Nocardia paucivorans.

Clinical relevance: To our knowledge, this is the first published report of canine infection with Nocardia paucivorans and the first case of peritoneal nocardiosis successfully treated in a dog. This report indicates that reducing the microbial burden by surgical debridement of affected tissues and peritoneal lavage followed by long-term treatment with a suitable antimicrobial may be an effective treatment for peritoneal nocardiosis in dogs.

Keywords: Peritoneal nocardiosis, Nocardia paucivorans, celiotomy, trimethoprim/sulfamethoxazole

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