Background: Cyathostomosis is the infection by nematode larvae of small strongyles belonging to the subfamily Cyathostominae(cyathostome). It is primarily a disease of young horses with global distribution. The parasites cause severe injuriesto the intestine and the clinically affected animals have severe diarrhea, colic, intussusception, and less frequently intestinalinfarction. The aim of this study is to describe the pathological findings of enteritis by cyathostome on a donkey in Brazil.Case: A donkey (Equus asinus), crossbred female mongrel, approximately four-months-old, was referred to the VeterinaryHospital of the Federal University of Campina Grande, Patos, PB, Brazil with a history of trauma. On clinical examination,complete fracture of the left femur was identified. After performing euthanasia the donkey was necropsied. The animal wasskinny with pale mucous membranes. The perineal region, base of the tail and hind limbs were dirty with yellowish fecalcontent. At necropsy, the large intestine had a pasty content and the mucosa was thickened with the multifocal whitish ordark red nodules. The cut surface of these nodules showed caseous material, sometimes associated with larvae in the submucosa.Microscopically, it was observed granulomatous and eosinophilic chronic multifocal associated with intralesionallarvae of cyathostome-like nematodes. In the mucosa and submucosa of the colon and cecum, there were multifocal tocoalescing granulomas composed by moderate inflammatory infiltrate composed of eosinophils, macrophages, epithelioidcells, neutrophils and occasional multinucleated giant cells, surrounded by fibrous tissue and infiltrated by lymphocytesand plasma cells. At the center of these granulomas transverse and longitudinal sections of nematode larvae with approximately160-550?m in diameter were observed within the necrotic material. The parasites presented a smooth, thick andeosinophilic outer cuticle, clear platymyarian muscles, internal cuticular crests, vacuolated lateral strings, and intestinecomposed of multinucleated cells in the large colon and caecum. There were no mature gonads, featuring the larval stage.Discussion: Parasitic infections are the most common diseases that threaten donkey health and performance. In this species,small strongyles infections are severe, since the larvae can infiltrate and form cysts in the wall of the large intestinecausing serious damage. The most common clinical signs caused by cyathostome are weight loss and diarrhea, which arenon-specific and consequently can lead to an underestimation of the disease occurrence. In this case, massive infection ofsmall strongyles was observed in the large colon and caecum. In contrast to the large strongyles, the small strongyles donot migrate through tissue but severely injure the large intestine of donkeys, zebras and horses. Other possible causes ofenteritis in horses include Salmonella spp., Rhodococcus equi, Clostridium perfringens, Clostridium difficile, Neorickettsia(Ehrlichia) ristcii infections, and idiopathic and neoplastic conditions (lymphoma). In the present report, the diagnosisof larval ciatostomose was based on clinical signs, and especially in the severity of pathological findings associated withmorphological characteristics of the larvae of nematodes compatible with cyathostome in the large intestine.