Septic Peritonitis Secondary to Neoplasia in Two Canine Cancer-Bearing Patients Lacking Gastrointestinal and Hepatic Organ Rupture.

In this case report, we describe the presentation, diagnosis, and outcome of septic peritonitis secondary to neoplasia in patients lacking evidence of gastrointestinal content leakage, liver abscessation, or other treatment-associated risk factors. Two dogs presented with a diagnosis of neoplasia and nonspecific clinical signs such as lethargy, hyporexia, vomiting, and discomfort that was localized to the abdomen. The diagnoses at presentation consisted of a perianal tumor consistent with apocrine gland anal sac adenocarcinoma and systemic mastocytosis. Neither of the dogs was considered systemically immunocompromised or had received recent cytotoxic chemotherapy treatment or surgical procedures. A common finding on blood work in the two dogs was the presence of band neutrophils. The diagnosis of septic peritonitis via fluid analysis and cytology was delayed in both cases. No treatment for the supposed underlying cause of septic peritonitis was pursued and euthanasia was pursued in both cases owing to poor prognosis. On necropsy, one dog was suspected to have developed septic peritonitis because of an abscessed lymph node, and in the other case, no definitive source was identified. Septic peritonitis can arise secondary to neoplasia that is not primarily involving the liver or gastrointestinal tract in canine patients that lack treatment-associated risk factors.