Treatment of intestinal pythiosis in a dog with a combination of marginal excision, chemotherapy, and immunotherapy.

CASE DESCRIPTION: A 1.5-year-old mixed-breed dog was examined because of a 1-month history of anorexia, vomiting, diarrhea, and weight loss. CLINICAL
FINDINGS: The dog was very thin on physical examination (body condition score, 3/9). Results of all diagnostic tests were within reference limits except intestinal thickening and lymphadenopathy were identified on abdominal ultrasound examination. During exploratory laparotomy, thickening at the ileocecal-colic junction and within the transverse colon and mesenteric lymphadenopathy were identified, and the ileocecal-colic junction was resected. Histopathologic evaluation of the ileocecal-colic junction and full-thickness biopsy specimens from other sites as well as results of a serum ELISA were diagnostic for gastrointestinal Pythium insidiosum infection. TREATMENT AND OUTCOME: Pythiosis was initially treated medically with administration of itraconazole and terbinafine by mouth, but the colonic lesion was progressive with this regimen. Two months after diagnosis, a subtotal colectomy was performed; marginal excision (0.6 cm) was obtained at the aboral margin. The dog was treated with 3 doses of a pythiosis vaccine beginning approximately 2 weeks after surgery and was continued on itraconazole and terbinafine for 5 months. Parenteral and enteral nutrition as well as considerable general supportive care were required postoperatively. Six months after treatment, the dog had a normal serum ELISA titer. Two years after treatment, the dog had returned to preoperative weight and was clinically normal. CLINICAL RELEVANCE: This patient had an unusually positive therapeutic response to chronic, extensive, marginally excised gastrointestinal pythiosis.