Pitiose gástrica em cão: Relato de caso

Abstract

Pythiosis is a progressive granulomatous disease caused by Pythium insidiosum, a microorganism belonging to the class of Qomycetes. This disease is common in horses, in the cutaneous form, and rarely affects dogs, having a gastrointestinal form. In canine gastrointestinal pythiosis, clinical manifestations are nonspecific and include vomiting, bloody diarrhea and weight loss. The disease has an unfavorable prognosis and is often diagnosed after the death of the animals, through histopathological and immunohistochemical or molecular findings. This study aimed to report the clinical, ultrasonographic and anatomopathological findings of gastric pythiosis in a dog. A six-year-old mixed breed female dog was treated at the Veterinary Hospital of the Federal University of Paraiba with a history of hematemesis, melena and progressive weight loss. Due to the lack of diagnosis in hematological and ultrasound examinations or effectiveness of clinical treatment, an exploratory laparotomy was performed. Given the unfavorable prognosis, the patient was euthanized and referred for anatomopathological examination. Macroscopically, the stomach had an irregular serous surface, diffuse transmural thickening with irregular cutting edges and a gelatinous and translucent appearance; the mucosa was diffusely thickened with reddish, multifocal, firm nodules, measuring between 0.8 and 1.51 cm in diameter, multifocal to coalescing yellowish-white granular areas, and reddened focally extensive areas. On microscopy, diffuse and transmural inflammation was observed, from the mucous layer to the serosa, predominantly composed of eosinophils, macrophages, neutrophils and plasma cells, associated with collagenolysis and multifocal areas with elongated tubular structures with basophilic outer membrane and pale interior, similar to hyphae , surrounded by a radiating sosinophilic mass (Splendore-Hoepplin), confirmed by Grocott-Gomori silver methenamine staining (GMS), being compatible with Pythium sp. The observed changes are compatible with infection by Pythium sp., restricted to the stomach. This is a rarely reported presentation in dogs, intestinal involvement being more common.