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Objective—To determine the effects of 8 days of light to heavy exercise on gastric ulcer development in horses and determine the efficacy of omeprazole paste in preventing gastric ulceration. Design—Randomized, controlled, multicenter clinical trial. Animals—102 horses with normal-appearing gastric mucosa on endoscopic examination that were in light to heavy training. Procedures—Horses at 4 trial locations were allocated into replicates and sham dosed orally (empty syringe) or treated with a paste formulation of omeprazole (1 mg/kg [0.45 mg/ lb], PO) once daily for 8 days. Training regimens varied among locations and included early training for western performance events; walking, trotting, and cantering in a mechanical exerciser; and race training (2 locations). Prevalences of gastric ulceration at the completion of the 8-day treatment period were compared between groups. Results—At the end of the 8-day treatment period, the proportion of omeprazole-treated horses free from gastric ulceration (88%) was significantly higher than the proportion of sham-dosed horses free from gastric ulceration (27%). Conclusions and Clinical Relevance—Results showed that horses in light to heavy training for as short as 8 days were at risk of developing gastric ulcers and that administration of omeprazole paste decreased the incidence of gastric ulcers.

Gastroendoscopy was performed on 111 horses (1 to 22 years old) that had signs of abdominal discomfort of variable duration and severity. At least 1 episode of colic had been observed within 48 hours of examination in 31 horses. Recurrent episodes of colic were observed in 28 horses within 2 to 10 days of examination, 31 horses within 11 to 30 days, 12 horses within 31 to 60 days, and in 9 horses at more than 60 days after the initial examination. Gastric ulceration was found in 91 of 111 horses examined. Other abnormalities involving the gastrointestinal tract or other abdominal viscera were not found on examination in 57 of 91 horses with gastric ulcers. The most frequent concurrent abnormalities found in the remaining 34 horses with gastric ulcers were impaction of the large colon (n = 6), colonic tympany (n = 6), peritonitis (n = 6), gastric impaction (n = 4), ileocecal intussusception (n = 3), small-colon impaction (n = 4), and proximal enteritis (n = 2). Thirteen horses with gastric ulceration underwent abdominal surgery, and in 5 horses, lesions were not found at surgery. Gastric ulceration was determined to be the primary cause of colic in 31 horses on the basis of the lack of other abnormalities, clinical response to treatment with histamine type-2 receptor (H2) antagonists, and confirmation of improvement or resolution of gastric ulceration via endoscopy. Gastric ulceration was the suspected cause of colic in 26 other horses on the basis of the lack of other abnormalities, severity of lesions, and clinical response to treatment with H2 antagonists.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypothyroidism was diagnosed in a neonatal Thoroughbred foal that was weak, hypothermic, and septicemic. Administration of thyroid-releasing hormone elicited attenuated increases in concentrations of free and total triiodothyronine and thyroxine, as compared with a clinically normal, age-matched foal. The foal died of apparent respiratory insufficiency, pre- and postmortem findings compatible with hypothyroidism included hypothermia, large thyroid glands with distended, colloid-filled follicles, and severe, diffuse atelectasis, with thickened alveolar septae and degenerating alveolar squamous epithelial cells.

Gastroendoscopic examinations were conducted on thirty-two 2- to 60-day-old Thoroughbred foals on 5 breeding farms. Repeat gastroendoscopic examinations were performed 35 to 135 days after the initial examination, with the age of foals ranging from 39 to 190 days. On initial endoscopic examination, lesions consisting of ulcers and/or erosions were most prevalent in the stratified squamous epithelial mucosa adjacent to the margo plicatus along the greater curvature of the stomach (15 of 32 foals), and were observed much less frequently at other sites within the stomach. In addition to ulcers and erosions, squamous epithelial desquamation at the margo plicatus was observed in 16 of 19 foals less than 30 days old and in 3 of 13 foals 30 to 60 days old, and was not seen in any foal on repeat endoscopy. At the time of repeat endoscopic examination, the frequency of ulcers and erosions at the margo plicatus was significantly (P less than 0.01) less than at initial examination (4 of 32 foals vs 15 of 32 foals). Lesions had healed in 14 of the 15 foals with lesions at the margo plicatus on the initial examination. Lesions were observed in the glandular mucosa of the fundus in 3 of 32 foals on initial examination and in 6 of 32 foals reexamined. Lesions in the glandular fundus observed on initial examination had healed in 2 of 3 foals, and of the 6 foals with glandular mucosal lesions on reexamination, 5 had developed lesions since the initial examination.(ABSTRACT TRUNCATED AT 250 WORDS)

A 6-month-old Clydesdale filly had chronic abdominal distention and intermittent febrile episodes. Abdominal surgery revealed impaction of the right dorsal colon, which was relieved by evacuation of contents through an enterotomy. Four days after surgery, abdominal distention recurred and progressed. The filly was euthanatized. Necropsy revealed the right dorsal colon to be markedly distended with digesta. Microscopically, there was a marked reduction in myenteric ganglion cells in the right dorsal colon and cecum and mild to moderate reduction of myenteric ganglion cells in the left ventral and transverse colon.

A 4-year-old mixed-breed gelding was presented with colic-type behavior of 5 days' duration that included pawing, looking at the flank area, and kicking and biting at the abdomen and flank when it was eating hay or grain. Medical evaluation did not reveal the cause of the "colic." During its stay in the hospital, the horse improved as regarded the colic-type behavior while eating, but resumed this behavior when it was able to see hay that it was not allowed to eat. It was determined that the persistent colic-type behavior developed as a result of the horse having been repeatedly displaced from its food by other horses. When the horse performed the colic-type behavior, the owner would remain with it and effectively protect it from competitors. The initial bout of colic may have been a result of true colic, psychosomatic colic secondary to stress, redirected aggression, or displacement activity.

Of 183 foals examined by use of gastroendoscopy during 1987 and 1988, 94 had gastric lesions. Sixty-eight of 120 foals in the 1- to 85-day-old age range had endoscopically confirmed gastric lesions, and 26 of 63 foals in the 90- to 310-day-old age range had gastric lesions. Lesions were observed most frequently in the stratified squamous mucosal epithelium, particularly adjacent to the margo plicatus. Lesions were observed in the gastric glandular mucosa in 26 of the 94 foals with gastric lesions, and with a greater frequency in foals with a clinical disorder than in foals with no disorder (27% vs 3%). In young foals, lesions were consistently observed in the stratified squamous mucosal epithelium adjacent to the margo plicatus along the greater curvature of the stomach at 2 specific sites. These lesions were frequently associated with desquamation of the stratified squamous mucosal epithelium, which was observed in 69 of the 82 foals less than or equal to 30 days old and in 13 of the 101 foals greater than 30 days old. Lesions in the stratified squamous mucosal epithelium adjacent to the margo plicatus were associated with concurrent clinical disorders in foals greater than 90 days old, but developed with identical frequency in foals less than 90 days old with or without a clinical disorder. Lesions in the stratified squamous mucosal epithelium along the lesser curvature of the stomach were observed only in foals with concurrent clinical disorder, and with a higher frequency in foals greater than 90 days old than in younger foals (24% vs 3%).

A 3-month-old foal with a history of persistent fever and leukocytosis was found to have pneumonia, ulceration of the squamous portion of the stomach, and dilatation of the distal portion of the esophagus. The foal was euthanatized and necropsied. The distal portion of the esophagus was severely dilated, and there was severe ulceration and mural thickening of the stomach at the cardia. Because of the severe gastric ulceration and mural thickening, the gastroesophageal junction was fixed in an open position, permitting gastroesophageal reflux. The megaesophagus and pneumonia were considered to have resulted from chronic gastroesophageal reflux.