Epidemiological and pathological aspects of noninfectious diseases of the gastrointestinal tract in 114 horses in Southern Brazil

Abstract

ABSTRACT: Equine colic is one of the most common cause of death in horses, but few studies have investigated specifically the conditions at the necropsy. This study aimed to describe the epidemiological and pathological features of noninfectious diseases of the gastrointestinal tract in horses. A retrospective study was conducted in search of cases of these diseases affecting horses from 2005 to 2017. During this period, 114 horses died of noninfectious diseases of the gastrointestinal tract, and the main causes were: primary gastric dilation (27/114), volvulus (27/114), enterolithiasis (20/114), rectal (colonic) perforation (15/114), gastric or cecocolonic impaction (10/114), incarcerations (6/114), intussusception (4/114), and others (5/114). Mixed breeds horses (56/114) and males (69/114) were mostly affected. The horses had a median and mean age of 10 and 10.9-years old, respectively. Primary gastric dilation was characterized by distension of the stomach by moderate to large amounts of content, which in 21 cases caused tearing of the stomach wall at the greater curvature (peritonitis), and the main predisposing factor was alimentary overload (17/27). Intestinal volvulus occurred within the small intestine (14 cases) and within the large intestines (13 cases). Grossly, there was intestinal ischemia with reddened to deep-black serosa and diffusely red mucosae. Enterolithiasis caused partial or complete obstruction of the right dorsal colon (9/20), transverse colon (4/20), small colon and right dorsal colon (3/20), rectum and right dorsal colon (2/20), and small colon (2/20). Viscera perforation and peritonitis occurred in 11 cases. Rectal (colonic) perforation involved the rectum (10/15), rectum/small colon (4/15), and the small colon (1/15). It was characterized by a focally extensive transmural tearing, associated with reddened borders, and retroperitoneal to diffuse peritonitis. Palpation related iatrogenic injuries (11/15) were the main cause. Impactions affected the large colon (7/10), the cecum (2/10), and the stomach (1/10). Incarcerations consisted of inguinoscrotal hernias (2/6), small intestine entrapment by a mesenteric failure (2/6), diaphragmatic hernia, and umbilical eventration. Grossly, the organs were constricted by a hernial ring, with intestinal ischemia and reddened to dark-red serosa. Predisposing factors included previous surgeries (2/6) and patent inguinal ring (1/6). Intussusception involved the small intestine (3/4) and ileocecum (1/4). Foals with lack of colostrum intake and concomitant pneumonia was a characteristic presentation (3/4). Grossly, the intussusceptum slipped into intussuscipiens, with diffuse deep black-red discoloration. Other causes included large colon displacement (2/5), extrinsic and intrinsic obstruction of the small intestine (2/5), and an intestinal adenocarcinoma. Noninfectious gastrointestinal diseases are major causes of death in horses. Epidemiological and gross features of the conditions should be accounted to obtain a final diagnosis of the cause of the colic.