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Topic:Gastrointestinal Health
Gastrointestinal health in horses encompasses the study of the structure, function, and disorders of the equine digestive system. The equine gastrointestinal tract is complex, consisting of the stomach, small intestine, cecum, and large intestine, each playing a specific role in digestion and nutrient absorption. Research in this area often focuses on common disorders such as colic, gastric ulcers, and parasitic infections, which can impact a horse's overall health and performance. Investigations examine factors affecting gastrointestinal health, including diet, management practices, and the microbiome. This page compiles peer-reviewed research studies and scholarly articles that explore the physiology, pathology, and management of gastrointestinal health in horses.
Gastric pH monitoring in healthy, suckling pony foals. Gastric pH was monitored in neonatal foals from birth to 3 months of age. Background pH decreased, especially during the first week of life. Milk had complex effects that depended on pH prior to sucking, confounded by the age of the foal: nearly neutral background pH tended to be acidified after milk intake; moderately acid background pH tended to be neutralized; low background pH was only slightly increased by milk. Absolute magnitude of the effects of milk decreased with age. Existence of a proulcerative intragastric environment in preweaning foals is postulated, but this must be considered ...
Neuropeptide distributions in the colon, cecum, and jejunum of the horse. The pelvic flexure portion of the equine large colon is the proposed location of a pacemaker mechanism. This study was conducted to ascertain whether the distribution of certain putative neurotransmitters differs at the pelvic flexure compared to other sampling sites. Tissue samples were collected from the intestinal tracts of six horses. Serial sections from these samples were reacted with primary antisera specific for substance P, vasoactive intestinal polypeptide (VIP), methionine-Enkephalin, and calcitonin gene-related peptide (CGRP). The regional distribution of immunoreactive neuronal el...
Pharmacokinetics and metabolism of avermectins in livestock. The kinetics of avermectin disposition and metabolism in ruminant livestock and horses are reviewed with particular emphasis on the influence of route of administration and formulation on persistence of residues in tissues and excretion in faeces. Because information is not publicly available on other compounds in this class currently under development (e.g. moxidectin, doramectin), ivermectin only is considered. The biological half-life of ivermectin in plasma is similar in cattle and sheep but because of a larger volume of distribution, plasma clearance is more rapid in sheep. However, injec...
Morphologic characterization of castor oil-induced colitis in ponies. Ten ponies (160-250 kg, ages 17 months to 20 years) developed severe diarrhea within 24 hours of castor oil administration (2.5 ml/kg orally). The diarrhea was most severe between 24 and 48 hours post-dosing and subsided by 72 hours. Ponies were euthanatized at 24, 48, and 72 hours post-dosing and intestine was evaluated histologically and ultrastructurally. Twenty-four hours after dosing, the mucosa of the cecum and ventral colon had extensive superficial epithelial erosion and neutrophil infiltration. In the ileum, the epithelium of villous tips was separated from the lamina propria. Scannin...
Effect of sucralfate on healing of subclinical gastric ulcers in foals. The effect of sucralfate on healing of subclinical gastric ulcers and gastric inflammation was investigated in twelve 6- to 7-month-old foals. Foals with endoscopically evident gastric lesions on day 0 were assigned to 1 of 2 groups, on the basis of mucosal inflammation and number and severity of ulcers, to create groups of foals with approximately equal severity of lesions. None of these foals had clinical signs of gastroduodenal ulcer disease. Groups were assigned to receive sucralfate (22.0 mg/kg of body weight) or corn syrup for 14 days, PO, every 8 hours. On day 15, gastroscopic examinati...
Comparative immunohistolocalization of carbonic anhydrase isozymes I, II and III in the equine and bovine digestive tract. Immunohistochemical localizations of carbonic anhydrase isozymes (CA-I, CA-II and CA-III) in equine and bovine digestive tracts were studied. In the horse, epithelial cells in both the oesophagus and non-glandular part of the stomach lacked all three isozymes. In contrast, surface epithelial and parietal cells in the glandular region of the stomach showed reactivity for CA-II. In the small intestine, absorptive columnar cells covering the villi in the duodenum were positive for CA-II. The epithelium of the jejunum and ileum lacked all three isozymes. In the large intestine, CA-II was detected ...
Some aspects of perinatal maturation and adaptation. Physiological challenges facing the perinatal individual are huge. This is partly because of the marked and abrupt change from the intrauterine to the extrauterine environment, but also because the physiological responses to that change depend upon systems whose maturation is affected markedly by birth. Perinatal maturation appears, therefore, both to precede and accompany the physiological adaptations required for neonatal survival. This review does not provide a comprehensive coverage of perinatal physiology but directs attention towards evaluating constraints on foetal and neonatal thermoge...
Serological titers of equine monocytic ehrlichiosis associated with gastro-intestinal disorders and serological follow-up on two endemic farms. The purpose of this work was to study the association of positive serological titers to Ehrlichia risticii, the causative agent of equine monocytic ehrlichiosis (EME) with gastro-intestinal disorders in hospitalized horses referred to The Ohio State University College of Veterinary Medicine Teaching Hospital (OSU VMTH). In addition, serological titers for E. risticii were monitored in two horse populations with endemic EME for one season to monitor temporal changes in titers. A statistically significant difference was found between the proportion of the total hospitalized horse population pres...
Use of a modified Roux-en-Y procedure for treatment of pyloroduodenal obstruction in a horse. A modification of the Roux-en-Y anastomosis procedure was used to bypass a pyloroduodenal mass in a 12-year-old Arabian stallion. Clinical signs had consisted of a 4-week progression of ventral and hind limb edema, hypoproteinemia, fecal occult blood, intermittent abdominal pain, weight loss, and gastric reflux. On exploratory celiotomy, an obstructive mass was found in the pylorus and proximal portion of the duodenum. Gastrojejunostomy and duodenojejunostomy were performed by use of stapled side-to-side anastomosis techniques. Inaccessibility of the obstructed pyloric region prevented resecti...
Duodenal perforations and gastric ulcers in foals. The history, clinical signs, post mortem and histopathological findings from two foals with perforating gastroduodenal ulcers and one foal with a non-perforating gastric ulcer are compared with those of other species with similar lesions. Two of the foals had several erosions in the oesophageal mucosa and the condition had been associated with strictures in the duodenum. The cause of the disease remains obscure but a possible connection with stress has been suggested.
Duodenal leiomyoma associated with colic in a two-year-old horse. A 2-year-old horse with signs of colic, reflux on nasogastric intubation, and large colon distention on transrectal palpation was found to have a leiomyoma involving the duodenum. The mass was excised without penetration of the lumen of the small intestine, and the horse recovered without complications.
Incarceration of the large colon in the gastrosplenic ligament of a horse. Incarceration of the large colon through a rent in the gastrosplenic ligament of a horse was surgically corrected via ventral midline celiotomy. Clinical signs were similar to those in other horses with nonstrangulating large colon disorders. Diagnosis of large colon incarceration in the gastrosplenic ligament was determined by surgical abdominal exploration. The findings of medial deviation of the spleen, location of the large colon lateral to the stomach and caudolateral to the spleen, and caudocraniad passage of the large colon through the gastrosplenic ligament are similar to findings in h...
Pathological lesions associated with Anoplocephala perfoliata at the ileo-caecal junction of horses. The intestinal tracts of 20 horses, killed at a local abattoir and of unknown age, sex and previous clinical history were examined for the presence of Anoplocephala perfoliata attached to the ileo-caecal junction. Four horses had no tape-worms, nine had one to 20 tapeworms attached to the mucosa and seven had more than 100 attached to the mucosa. The histological changes of thickening, ulceration and eosinophil infiltration of the mucosa at the ileo-caecal junction were more severe when more than 100 parasites were present.
Clostridium difficile associated with typhlocolitis in an adult horse. No abstract available
Technique for long-term right dorsal colon fistulization in ponies. Right dorsal colon fistulas, 2.5 cm in diameter, were created in 2 healthy ponies, using a 2-stage surgical procedure. The first stage consisted of resection of portions of the 16th and 17th ribs on the right side, followed by surgical creation of a 6- to 8-cm-diameter adhesion between the right dorsal colon and the body wall. Fistulas were created approximately 2 weeks after the first surgery by sharp dissection through the adhesion into the lumen of the colon. The fistulas have been satisfactorily maintained for > 2 years by de Pezzer catheters (45 F). Ponies with fistulas have been used ...
Comparison of adverse effects of phenylbutazone, flunixin meglumine, and ketoprofen in horses. The relative toxicity of phenylbutazone, flunixin meglumine, and ketoprofen was studied in healthy adult horses. Sixteen horses were randomly assigned to receive 10 ml of physiologic saline solution, or ketoprofen (2.2 mg/kg of body weight), flunixin meglumine (1.1 mg/kg), or phenylbutazone (4.4 mg/kg) IV, every 8 hours, for 12 days. Results of CBC, serum biochemical analyses, and fecal occult blood tests were monitored. On day 13, all horses were euthanatized and complete necropsy examinations were performed. Mean CBC values remained within normal limits for all groups. Phenylbutazone-treated...
Segmental ischemic necrosis of the small intestine in two postparturient mares. Two mares developed segmental ischemic necrosis of the small intestine after parturition. In one mare, the mesentery of the small intestine apparently tore during parturition, after which necrosis developed in a 52-cm segment of the distal portion of jejunum. In the other mare, a 52-cm segment of the proximal portion of ileum tore during parturition. Three weeks later, a 40-cm segment of the distal portion of jejunum became incarcerated in the mesenteric rent and twisted 360 degrees on its mesentery. Both mares recovered after resection of affected intestine and are functioning as broodmares.
Jejunal intussusception in adult horses: 11 cases (1981-1991). Medical records of 11 adult horses with jejunal intussusception examined at 5 veterinary teaching hospitals between 1981 and 1991 were reviewed. Nine of 11 horses had signs of acute abdominal discomfort for < 24 hours, whereas 2 horses had a history of chronic signs. Five of 11 horses had an intraluminal or intramural mass associated with the jejunal intussusception. Two horses died or were euthanatized prior to surgery. Partial jejunal resection and jejunojejunal anastomosis were performed in 9 horses. One horse died during surgery and 2 were euthanatized prior to hospital discharge becaus...
Characteristics of L-glutamine transport in equine jejunal brush border membrane vesicles. The sodium-dependent transporter system responsible for L-glutamine uptake by brush border membrane vesicles prepared from equine jejunum was characterized. Vesicle purity was ascertained by a 14- to 17-fold increase in activity of the brush border enzyme markers. Glutamine uptake was found to occur into an osmotically active space with negligible membrane binding. The sodium-dependent velocity represented approximately 80% of total uptake and demonstrated overshoots. Kinetic studies of sodium-dependent glutamine transport at concentrations between 5 microM and 5 mM revealed a single saturable...
Incarceration of the small intestine in the epiploic foramen. Report of 19 cases (1983-1992). The medical records of 19 horses referred for colic and subsequently found (18 confirmed, 1 suspected) to have small intestinal incarceration through the epiploic foramen were reviewed. These horses were of various ages and breeds; they had clinical signs of colic for an average duration of 13.5 hours before examination. Seventeen horses had nasogastric reflux, and 15 had palpable small intestinal distention. Three horses were killed during surgery because of severe intestinal damage. Of the remaining 16 horses, 13 required intestinal resection and anastomosis. The length of incarcerated small...
Ultrastructural mucosal injury after experimental ischemia of the ascending colon in horses. The ultrastructural injury that develops sequentially in the ascending colon during experimentally induced ischemia was examined in 6 halothane-anesthetized horses. Colonic ischemia was created by 2 types of vascular occlusion 24 cm proximal and distal to the pelvic flexure. In all horses, transmural vascular compression was created. The colonic venous circulation was obstructed in 3 horses, whereas in the other 3 horses, arterial and venous circulation was obstructed. Two additional horses were anesthetized as controls for determination of any morphologic alterations associated with the exper...
Ultrastructure of Brunner’s glands in the horse. Investigation of the duodenal submucosal glands of Brunner in the horse for the first time at the ultrastructural level has clarified some of the unique features of these equine glands. The horse is one of the very few mammals in which Brunner's glands are comprised of both mucous and serous tubuloacinar glands. Although the ultrastructural differences between the serous and mucous cell types are marked, particularly with respect to secretory granules and rough endoplasmic reticula, these cell types closely correspond to serous and mucous cells in the upper digestive system of other mammals. A...
Effect of the somatostatin analogue octreotide on gastric fluid pH in ponies. The effect of the somatostatin analogue, octreotide, on gastric fluid pH was investigated in 4 ponies. Gastric fluid pH was determined after SC administration of octreotide or physiologic saline solution (control). A baseline sample of fluid was obtained, the agent was given, and 8 additional samples were collected hourly. Administration of octreotide at all dosages tested (0.1, 0.5, 1.0, and 5.0 micrograms/kg of body weight) increased gastric pH to > 5.0. Baseline values were consistently 4.0 for 2.4 +/- 1.2, 4.8 +/- 0.8, 5.7 +/- 1.3, and 5.4 +/- 2.6 (mean +/- SD) continuous hours, respec...
Arteriovenous differences for glutamine in the equine gastrointestinal tract. Glutamine has been shown to be an important metabolic substrate of enterocytes in many animals, including cats, dogs, hamsters, human beings, monkeys, rabbits, rats, and sheep. To determine whether glutamine is important in the metabolism of cells of the equine gastrointestinal tract, we examined transintestinal differences in glutamine concentrations in the arterial and venous circulation, and measured activity of the major glutamine catabolizing enzyme, glutaminase. Arteriovenous differences provide an index of the amount of a given substrate removed by the tissue across which the measuremen...
Colopexy in broodmares: 44 cases (1986-1990). Colopexies were performed in 44 broodmares requiring abdominal surgery for large colon volvulus or right dorsal displacement of the large colon. Colopexies were performed by suturing the lateral bands of the left and right ventral colon to the ventral abdominal wall. Forty-seven percent of the mares in which a colopexy was performed had previous surgery for a large colon volvulus or right dorsal displacement of the large colon. Postoperative complications considered directly associated with the colopexy procedure were intermittent abdominal pain in 7, reoperation in 5, subcutaneous fistulous t...
Cholelith causing duodenal obstruction in a horse. A 10-year-old Appaloosa stallion was referred for evaluation of colic. At admission, the heart rate, capillary refill time, respiratory rate, and rectal temperature were high. Fifteen liters of reflux was obtained by nasogastric intubation. Palpation of an abdominal mass per rectum elicited signs of pain. At exploratory laparotomy, a mass was palpated in the ascending portion of the duodenum. The small intestine ruptured at the site of obstruction during manipulation. The horse was euthanatized. A large cholelith was the cause of the duodenal obstruction. At necropsy, multiple choleliths of va...
Effect of a histamine H2 type receptor antagonist (WY 45, 727) on the healing of gastric ulcers in ponies. Using video gastroscopy, the efficacy of a Histamine-H2 type receptor antagonist (WY 45, 727) was investigated in young ponies with spontaneous and experimentally induced gastric ulcers. Oral administration of WY 45, 727 at 2 mg/kg and 10 mg/kg of body weight every 12 hours for 14 days resulted in complete healing of spontaneous gastric ulcers in the non-glandular portion of the stomach in 2/5 (40%) and 3/4 (75%) of the ponies, respectively, compared (P < 0.05) to 0/5 (0%) placebo-treated ponies. After intramuscular administration of flunixin meglumine at 1.5 mg/kg body weight every 8 hours...
Effects of general anesthesia on myoelectric activity of the intestine in horses. Myoelectric activity was monitored from the terminal ileum, cecum, and colonic pelvic flexure by use of AgpAgCl bipolar electrodes in 4 adult horses before, during, and after general anesthesia. Horses were anesthetized by way of 3 commonly used regimens, including xylazine (1.1 mg/kg of body weight) and ketamine hydrochloride (2.2 mg/kg); thiopental sodium (7.7 mg/kg), followed by halothane vaporized in oxygen; and thiopental sodium (2.5 g) in guaifenesin (100 mg/ml) solution given to effect, followed by halothane in oxygen. All 3 anesthetic regimens decreased intestinal spike-burst activity ...
