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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.
Pharmacokinetics and adverse effects of butorphanol administered by single intravenous injection or continuous intravenous infusion in horses. To determine an infusion rate of butorphanol tartrate in horses that would maintain therapeutic plasma drug concentrations while minimizing development of adverse behavioral and gastrointestinal tract effects. Methods: 10 healthy adult horses. Methods: Plasma butorphanol concentrations were determined by use of high-performance liquid chromatography following administration of butorphanol by single IV injection (0.1 to 0.13 mg/kg of body weight) or continuous IV infusion (loading dose, 17.8 microg/kg; infusion dosage, 23.7 microg/kg/h for 24 hours). Pharmacokinetic variables were calculated, a...
Risk factors for reduced postoperative fecal output in horses: 37 cases (1997-1998). To determine prevalence and risk factors for development of ileus of the large intestine after surgery in horses, identified by reduced postoperative fecal output (RPFO). Methods: Retrospective study. Methods: 37 horses that developed RPFO after undergoing general anesthesia for reasons unrelated to the gastrointestinal tract. Methods: Fecal output was obtained from medical records as number of defecations per 24-hour period after surgery; RPFO was defined as or = 4 times during the same period. Demographic, clinical, and surgical variables were evaluated for their association with developmen...
Caecal impactions managed surgically by typhlotomy in 10 cases (1988-1998). Surgical management of caecal impactions has included several different procedures suggested over the years. Complete bypass of the caecum through an ileocolic or jejunocolic anastomosis has become common practice for first time caecal impaction management, especially when dysfunction is suspected. In our practice, however, caecal impactions have been managed surgically by typhlotomy alone and of the 10 cases (July 1988-June 1998), 9 underwent surgery for first time caecal impactions, received a typhlotomy, and had survived an average of 43 months at time of case review. At the time of surgery...
Abdominal radiography in monitoring the resolution of sand accumulations from the large colon of horses treated medically. This retrospective study consisted of 14 horses (age 6 weeks-12 years) with radiographically evident sand accumulations cranioventrally in the abdomen and clinical signs suggestive of sand enteropathy. The horses were treated medically and resolution of sand was monitored radiographically. Routine treatment consisted of psyllium mucilloid, combined with magnesium sulphate and/or mineral oilif needed. Initially, the number, size and shape of the sand accumulations showed large variation and the response to therapy was not predictable based on the initial appearance of the accumulation. In 2 foa...
Evaluation of uniformity of morphological injury of the large colon following severe colonic torsion. This report describes the evaluation of uniformity of morphological injury of the large colon following severe colonic torsion in 17 horses presented to the Veterinary Medical Teaching Hospital. In 16 horses, twist occurred at the colonic base and in 1 at the sternal and diaphragmatic flexure. Eleven of the 17 horses were subjected to euthanasia at surgery and 6 of 17 following surgical correction within 4 days postoperatively. The objective of this study was to determine if the degree of histological changes present at the pelvic flexure were uniformly distributed throughout the regions of th...
Equine lymphocytic-plasmacytic enterocolitis: a retrospective study of 14 cases. Lymphocytic-plasmacytic enteritis (LPE) is a morphological diagnosis given to a type of infiltrative intestinal disease classified within the complex of idiopathic inflammatory bowel disease (IBD). The purpose of this retrospective study was to describe the details of breed, age and sex, clinical and clinicopathological findings and outcome of horses diagnosed with LPE. Data were reported from 14 horses that had a histopathological diagnosis of LPE; the median age was 12 years, and there was no breed or sex predilection. Common clinical signs were weight loss (100%), diarrhoea (50%) and lethar...
The role of cyclooxygenase inhibitors in repair of ischaemic-injured jejunal mucosa in the horse. Cyclooxygenase inhibitors are administered to horses to prevent endotoxin-induced elaboration of prostaglandins. However, PGE2 and PGI2 stimulate repair of injured intestine. There are 2 isoforms of cyclooxygenase: COX-1, which constitutively produces prostaglandins and COX-2, which is induced by inflammation. We hypothesised that the nonspecific cyclooxygenase inhibitor flunixin meglumine would retard repair of ischaemic intestinal injury by preventing production of reparative prostaglandins, whereas the selective COX-2 inhibitor, etodolac, would permit repair as a result of continued COX-1 p...
[Diagnosis of stomach carcinoma in the horse]. In 10 horses, which were referred to the clinic with the suspicion of disorders of the gastrointestinal tract, gastroscopy revealed a gastric tumour. In ten cases the diagnosis of a squamous cell carcinoma was made on the basis of histology of biopsies or autopsy. The tumour always derived from the non-glandulary mucosa. The horses showed various clinical symptoms. All patients had a hypoalbuminemia and a hyperglobulinemia in the serum electrophoresis. This suggests that a gastric tumour can be suspected intra-vitam even without gastroscopy of the patient.
[Gastric ulceration in horses: etiology, diagnosis, and therapy: a review]. Since it has become possible to make an ante-mortem diagnosis of gastric ulceration in horses by means of endoscopy, interest in the presence and treatment of this syndrome has increased. Several endoscopic surveys have indicated that the frequency of gastric ulceration in Thoroughbreds in training is fairly high. Less is known about other breeds and horses that are kept under different (training) conditions. The equine stomach is covered by two different kinds of mucous membranes: squamous and glandular. These two areas differ from one another in the incidence and aetiology of ulceration and,...
Evidence for surfactant contributing to the gastric mucosal barrier of the horse. This study was undertaken to determine the hydrophobicity of the luminal surface of the equine stomach and to elucidate the ultrastructure of the lining imparting that property. Gastric and duodenal mucosal samples from 5 horses were collected immediately after euthanasia and subjected to surface contact angle measurement using a goniometer. Gastric mucosal samples from 4 horses and a foal were examined by electron microscopy following a fixation procedure known to preserve phospholipids and oligolamellar structures. Contact angles for the equine gastric glandular mucosal surface (mean +/- s.e...
Yohimbine ameliorates the effects of endotoxin on gastric emptying of the liquid marker acetaminophen in horses. The effect of yohimbine pretreatment on gastric emptying of a liquid marker in horses was evaluated by measuring serum concentrations of acetaminophen. Gastric emptying was determined in normal, fasted horses, in horses given endotoxin (E. coli 055 B5; 0.2 microg/kg) intravenously, and in horses given yohimbine (0.25 mg/kg, IV, over 30 minutes) plus endotoxin. Acetaminophen (20 mg/kg) was given by stomach tube 15 minutes after the endotoxin infusion. Blood samples for acetaminophen analysis were collected, and time to reach the peak serum concentration (Tmax), the maximum serum concentration (...
In vitro investigation of the effect of prostaglandins and nonsteroidal anti-inflammatory drugs on contractile activity of the equine smooth muscle of the dorsal colon, ventral colon, and pelvic flexure. To determine the in vitro effect of prostaglandin E2 (PGE2), PGF2alpha, PGI2; and nonsteroidal anti-inflammatory drugs (NSAID; ie, flunixin meglumine, ketoprofen, carprofen, and phenylbutazone) on contractile activity of the equine dorsal colon, ventral colon, and pelvic flexure circular and longitudinal smooth muscle. Methods: 26 healthy horses. Methods: Tissue collected from the ventral colon, dorsal colon, and pelvic flexure was cut into strips and mounted in a tissue bath system where contractile strength was determined. Incremental doses of PGE2, PGF2alpha,, PGI2, flunixin meglumine, carp...
Evaluation of substance P as a neurotransmitter in equine jejunum. To determine whether substance P (SP) functions as a neurotransmitter in equine jejunum. Methods: Samples of jejunum obtained from horses that did not have lesions in the gastrointestinal tract. Methods: Jejunal smooth muscle strips, oriented in the plane of the circular or longitudinal muscle, were suspended isometrically in muscle baths. Neurotransmitter release was induced by electrical field stimulation (EFS) delivered at 2 intensities (30 and 70 V) and various frequencies on muscle strips that were maintained at low tension or were under contraction. A neurokinin-1 receptor blocker (CP-96...
Entrapment of the small colon through a mesocolic rent in a mare. A 6-year-old mare was presented for acute abdominal pain unresponsive to analgesics. Exploratory laparotomy revealed entrapment of the small colon through a 12 cm rent in the mesocolon. The incarcerated small colon was manually reduced and the rent in the mesocolon was sutured closed. The mare made excellent postoperative recovery and was discharged from the hospital 4 days later. The cause of the rent, which was chronic in appearance, is unknown.
Idiopathic focal eosinophilic enteritis associated with small intestinal obstruction in 6 horses. To report the history, clinical findings, and outcome of horses with idiopathic focal eosinophilic enteritis associated with acute small intestinal obstruction. Methods: Retrospective study. Methods: Six horses with idiopathic focal eosinophilic enteritis. Methods: Retrospective review of medical records of horses with idiopathic focal eosinophilic enteritis, with acute abdominal pain and small intestinal obstruction, associated with a focal region of eosinophilic enteritis of unknown cause. Information retrieved from the medical records included signalment, physical examination, laboratory fi...
Effect of pyloric blockade and infusion of histamine or pentagastrin on gastric secretion in horses. To determine the origin of the nonacid (nonparietal) component of gastric secretions in horses induced by pentagastrin infusion. Methods: 6 horses. Methods: A Latin square design was used, involving 6 horses, 3 treatments, and 2 duodenal intubation conditions (catheter with balloon to obstruct pylorus [B] or without balloon allowing movement of contents between stomach and duodenum [NB]). Each horse had an indwelling gastric cannula and a catheter positioned in the duodenum. Gastric and duodenal contents were collected during 15-minute periods. Each experiment consisted of serial collection pe...
Functional morphology of the equine pelvic flexure and its role in disease. A review. The hindgut is the major site in the horse for nutrient digestion and absorption. Most of this activity occurs in the large intestinal compartments, i.e., cecum, right and left ventral colon and left and right dorsal colon. The colonic pelvic flexure is a short and narrow loop connecting the left ventral and left dorsal colon. It is not significant directly in digestive and absorptive processes but plays an important functional role in regulating colonic aboral and retropropulsive transit of digesta through its motility pacemaker activity. The pelvic flexure also contributes to the pathophysio...
The application of technetium-99m hexamethylpropyleneamine oxime (99mTc-HMPAO) labeled white blood cells for the diagnosis of right dorsal ulcerative colitis in two horses. The application of 99mTc-HMPAO labeled white blood cells to support the diagnosis of right dorsal ulcerative colitis was studied in two horses with a history and clinical signs consistent with phenylbutazone toxicity. These images were compared to a reference horse unaffected by right dorsal ulcerative colitis. Blood was collected aseptically in heparinized syringes from the patients for in vitro white blood cell (WBC) radiolabeling. The buffy coat was separated out and radiolabeled with 99mTc-HMPAO. The radiolabeled blood was re-injected i.v. and four images of the right and left side of the ...
Influence of bacitracin on microbial functions in the gastrointestinal tract of horses. This study investigated the influence of zinc bacitracin on the intestinal flora of horses. The functionally active intestinal flora was examined in 6 horses during treatment with zinc bacitracin. Utilising gas chromatography, spectrophotometry, gel electrophoresis and paper chromatography, samples were analysed on biochemical markers reflecting the action of parts of the intestinal flora. The following 5 flora-related functions were studied in faecal samples and intestinal samples from different sections of the hindgut: conversion of cholesterol to coprostanol and of bilirubin to urobilinogen...
In vitro evaluation of intraluminal factors that may alter intestinal permeability in ponies with carbohydrate-induced laminitis. To study the in vitro effects of cecal contents incubated with corn starch on colonic permeability in horses. Methods: 4 healthy adult ponies. Methods: Mucosal specimens were obtained from the right ventral colon and mounted in Ussing chambers. Changes in short circuit current, conductance, and large-molecule permeability in response to addition of cecal contents and cecal contents incubated with corn starch were evaluated for 120 minutes. Results: Incubation of cecal contents with corn starch for 8 hours resulted in a decrease in cecal content pH and an increase in lactic acid concentration. ...
Evaluation of diet as a cause of gastric ulcers in horses. To measure pH, volatile fatty acid (VFA) concentrations, and lactate concentrations in stomach contents and determine number and severity of gastric lesions in horses fed bromegrass hay and alfalfa hay-grain diets. Methods: Six 7-year-old horses. Methods: A gastric cannula was inserted in each horse. Horses were fed each diet, using a randomized crossover design. Stomach contents were collected immediately after feeding and 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, and 24 hours after feeding on day 14. The pH and VFA and lactate concentrations were measured in gastric juice Number and severity of gastri...
Risk factors for enterolithiasis among horses in Texas. To identify risk factors for enterolithiasis in horses. Methods: Matched case-control study. Methods: 26 horses with enteroliths, 104 horses with other causes of colic that underwent surgery (52 horses, surgical control group) or were treated medically (52 horses, nonsurgical control group). Methods: Medical records were reviewed for horses with enteroliths and control horses. Information collected included signalment, anamnesis, and findings on physical examination and clinicopathologic testing at admission. Horses with enteroliths and control horses were compared by means of conditional logi...
Chronic idiopathic inflammatory bowel diseases of the horse. A review of reported cases of inflammatory bowel diseases (IBDs) of horses for which no etiology was identified included cases of granulomatous enteritis (GE), multisystemic eosinophilic epitheliotropic disease (MEED), lymphocytic-plasmacytic enterocolitis (LPE), and idiopathic eosinophilic enterocolitis (EC). The terms EC and MEED were both used to describe a disease in horses characterized by infiltration of intestine and extraintestinal tissues with eosinophils. We use EC to describe IBD characterized by only intestinal infiltration by eosinophils. Horses with GE, MEED, or LPE are usually e...
Intracellular microelectrode recording to characterize inhibitory neuromuscular transmission in jejunum of horses. To evaluate electrical activity of jejunal circular muscle in horses and characterize electrical responses to stimulation by intrinsic inhibitory neurons. Methods: Portions of jejunum obtained from horses euthanatized for reasons other than gastrointestinal tract disease. Methods: Isolated circular muscle preparations were perfused with oxygenated modified Krebs solution. Glass microelectrodes were used for intracellular recording of membrane potentials from single smooth muscle cells. Electrical activity and responses to electrical field stimulation (EFS) of intrinsic neurons in the presence ...
Prokinetic effects of erythromycin on the ileum, cecum, and pelvic flexure of horses during the postoperative period. To evaluate the effect of erythromycin on motility of the ileum, cecum, and pelvic flexure of horses during the postoperative and post-recovery periods. Methods: 8 healthy adult horses. Methods: Horses were anesthetized and bipolar electrodes were implanted in smooth muscle of the ileum, cecum, and pelvic flexure. Approximately 4, 16, and 24 hours (postoperative recording sessions) and at least 8 days (post-recovery recording session) after surgery, myoelectric activity was recorded before and after administration of erythromycin (0.5 mg/kg). Results: Following erythromycin administration, myo...
In vitro effects of erythromycin, lidocaine, and metoclopramide on smooth muscle from the pyloric antrum, proximal portion of the duodenum, and middle portion of the jejunum of horses. To evaluate effects of erythromycin, lidocaine, and metoclopramide on smooth muscle of the pyloric antrum (PA), proximal portion of the duodenum (PD), and middle portion of the jejunum (MJ) of horses. Sample Population-Strips of smooth muscle from 7 horses. Methods: Isolated muscle strips were suspended in a bath and attached to isometric force transducers. Once stable spontaneous contractions were observed, agents were added. Isometric stress responses were compared with the amplitude of spontaneous contractions. Results: A single dose of erythromycin to the PA increased contractile amplitude...
