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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.
Regional gastric pH measurement in horses and foals. The pH of the gastric mucosal surface and gastric content was measured in 18 foals (mean age: 20 days) and 27 horses (mean age: 2.9 years) with a pH electrode passed through an endoscope biopsy channel. A reference electrode was attached to a shaved area on the neck. pH Measurements of the gastric mucosal surface at the dorsal squamous fundus (SF), squamous mucosa adjacent to the margo plicatus (MP), glandular fundus (GF) and the fluid or feed contents of the stomach were recorded in duplicate for each animal. In adult horses, the SF pH was greatest (5.46 +/- 1.82), with a decreasing pH ventra...
Antibody titres to core lipopolysaccharides in horses with gastrointestinal disorders which cause colic. Serum immunoglobulin (Ig) titres to core lipopolysaccharide (LPS) were determined in 102 horses admitted to a university referral hospital during a 12-month period for evaluation of colic. Serum samples were collected again 10-14 days later from 84 of the horses. Titres to core LPS were quantitated by an indirect enzyme-linked immunosorbent assay (ELISA), utilising the J-5 mutant of Escherichia coli 0111:B4 as the solid-phase antigen. All horses had natural antibodies to core LPS at the time of admission and the titre was not affected significantly by age, sex or type of gastrointestinal disor...
Cisapride in the prophylaxis of equine post operative ileus. Cisapride and domperidone were both effective in restoring electrical and mechanical activity, coordination between gastric and small intestinal activity cycles and the stomach to anus transit time in three ponies in which post operative ileus was induced experimentally. Cisapride (0.1 mg/kg bodyweight intramuscularly) for three to eight doses prevented idiopathic post operative ileus in 22 clinical cases requiring colic surgery. The only side effects after cisapride were increased bowel sounds and slight, transient sounds of discomfort. No adverse side effects were seen in 16 cases following ...
Correlative morphometry and morphology of normal equine intestinal mucosa and comparison after adaptation to extensive large colon resection. Light microscopy, morphometry and scanning electron microscopy (SEM) were used to examine the mucosal morphology of seven intestinal specimens (three from the small intestine and four from the large intestine) from two horses not subjected to surgery and three horses one year after sham-operation for colon resection. Qualitative and quantitative evaluation revealed similar morphology for all horses except that the unoperated horses had significantly (P < 0.05) fewer goblet cells in the crypts of the large intestine. In the small intestine, SEM demonstrated that villus shape varied and range...
Plasma endotoxin concentrations in experimental and clinical equine subjects. Endotoxin (LPS) was quantitated in experimental subjects and in horses with naturally occurring gastrointestinal strangulation obstruction and/or septicaemic diseases to establish the fate of LPS and the clinical usefulness of the Limulus amoebocyte lysate (LAL) assay. The assay was validated for sensitivity (10 pg/ml), recovery (90 to 106 per cent), intra-assay precision (CV = 5.5 per cent) inter-assay precision (CV = 11 per cent), and stability of diluted, heat treated, frozen samples (at least 90 days). Plasma concentrations of LPS after sublethal (3 micrograms/kg) jugular or portal vein bo...
Comparison of age, sex, breed, history and management in 229 horses with colic. A study, at a university in south eastern USA, aimed to determine whether age, sex, breed, management and history differed in colic cases. A detailed history was obtained for 229 horses between January 1987 and June 1988. Causes for colic determined by clinical examination, exploratory laparotomy and/or necropsy included: gastric rupture (GR, 6); ileal impaction (II, 17); small intestinal strangulating obstruction (SIO, 22); proximal enteritis (PE, 16); transient small intestinal distension (TSID, 18); large colon displacement (LCD, 52); large colon impaction (LCI, 34); colitis (8); small colo...
Effects of diet and feeding on postprandial serum gastrin and insulin concentration in adult horses. Gastrin is the only hormone known to stimulate secretion of hydrochloric acid. It also has trophic effects on specific parts of the mucosa of the gastrointestinal tract. Using radioimmunoassay techniques, postprandial serum gastrin and insulin concentrations were measured in six adult horses to establish effects of different diets on gastrin concentrations. Insulin concentrations were measured to provide support to the patterns of gastrin secretion because patterns of insulin secretion were already known. The horses were fed coastal bermuda hay, or twice daily 5 kg of a complete pelleted ratio...
Effect of butorphanol on equine antroduodenal motility. Six healthy six to eight-month-old horses were surgically prepared with Ag bipolar electrodes sutured to the gastric antrum and duodenum. Leads from the electrodes were exteriorised through a stab incision in the flank. During experimental sessions the horses were lightly restrained in stocks and electrode leads were connected to a physiograph to record antroduodenal myoelectrical activity. Intravenous (i.v.) injection of 0.05 mg/kg bodyweight (bwt) of the opioid agonist/antagonist, butorphanol was followed within 2 to 3 mins by a normal appearing period of repetitive spike activity, or phase ...
Castor-oil induced diarrhoea in ponies: a model for acute colitis. A reproducible, reversible model of colitis induced in ponies by administering castor oil (2.5 ml/kg bodyweight [bwt] per os) was characterised by abdominal pain, fever, watery diarrhoea, dehydration, hypovolaemia, toxaemia, leucopenia, decreased serum Cl, Na and K levels and metabolic acidosis. The signs were most severe between 24 and 48 h post induction, stabilisation was frequently observed after 72 h, although diarrhoea could persist beyond 96 h. Morphological and in vitro transport studies (right ventral colon) were conducted on tissues from animals destroyed at 24, 48 and 72 h. In the c...
Effect of xylazine treatment on equine proximal gastrointestinal tract myoelectrical activity. Five 5 to 6 month old horses were surgically prepared with silver electrodes sutured to the serosa of gastric antrum, duodenum and proximal portions of the jejunum. Normal migrating motility complex (MMC) periodicity was determined during daytime hours in horses that were fed and horses from which food was withheld for 24 hours. Periodicity was defined as time span from the end of one period of regular spike activity (RSA) to the end of the next RSA in the MMC. The periodicity was 120.5 +/- 9.5 (SEM) minutes in horses from which food was withheld, and was 125.7 +/- 20.3 minutes in horses fed h...
Antagonism of endotoxin-induced disruption of equine bowel motility by flunixin and phenylbutazone. Post operative ileus is a serious complication of abdominal surgery in horses and there is evidence that endotoxin plays a significant role in its pathogenesis. Pre-treatment with intravenous (i.v.) flunixin (1.1 mg/kg bodyweight [bwt]) or phenylbutazone (4.4 mg/kg bwt) significantly antagonised the acute disruption of gastric, small intestinal and large intestinal motility induced by 0.1 microgram/kg bwt i.v. endotoxin in ponies implanted with gastrointestinal strain gauges. Phenylbutazone was more effective than flunixin and this was significant (P < 0.01) for the stomach and left dorsal ...
Surgical management of duodenal obstruction in an adult horse. A 3-year-old Standardbred stallion was admitted for treatment of acute enterocolitis. The horse improved in response to empiric treatment, but subsequently developed ventral edema, scrotal abscessation, and severe laminitis. Improvement again was seen, but on day 29 of hospitalization, the horse developed rapid heart rate and signs of abdominal pain. Exploratory celiotomy revealed complete obstruction of the descending portion of the duodenum, 20 cm caudal to the duodenal sigmoidal flexure. Three-tier duodenojejunostomy and jejunojejunostomy were performed to bypass the duodenal obstruction.
Observations on gamma-glutamyl transferase, 5′-nucleotidase and leucine aminopeptidase activities in the plasma of the horse. In 18 horses there was no effect of age or sex on plasma activities of gamma-glutamyl transferase (gamma-GT), 5'-nucleotidase (5'-NT) and leucine aminopeptidase (LAP). All the enzymes were equally stable after storage for one month at -20 degrees C and there was no significant difference between their activities in serum and plasma in clinically normal horses. The pattern of release of gamma-GT, 5'-NT and LAP into plasma was studied in 114 horses which had a variety of orthopaedic, gastrointestinal, cardiovascular and hepatic (necrosis, lipidosis, neoplasia and cirrhosis) conditions. A definit...
The protective effects of sucralfate and ranitidine in foals experimentally intoxicated with phenylbutazone. The effects of sucralfate and ranitidine on the gastrointestinal manifestations of phenylbutazone (PBZ) toxicity in horse foals were determined by complete blood count, serum chemistry profile, and gross and histological necropsy examinations. Twenty-eight, three to four month old Belgian-cross foals were randomly assigned to one of four groups. Phenylbutazone was administered at a dosage of 10 mg/kg of bodyweight (BW) per day, intravenously (IV), in equally divided doses to three of the groups. In addition to PBZ, ranitidine was administered at 2 mg/kg BW, IV, twice daily, to one group of sev...
Clinical and pathological effects of flunixin meglumine administration to neonatal foals. The effects of daily intravenous administration of flunixin meglumine at dosages of 0.55, 1.1, 2.2 and 6.6 mg/kg for five days were examined in neonatal foals. Six two day old foals were used to evaluate the effect of each dosage. Foals were examined every day and blood samples collected on days 1, 3 and 6. All foals were euthanized after six days, necropsied and examined for lesions. The major clinical abnormality was diarrhea, but the incidence was not related to the dosage of flunixin meglumine administered. The foals receiving 6.6 mg/kg of flunixin meglumine had significantly more gastroin...
Vascular anatomy of the descending colon of the horse. The blood supply to the descending colon of the horse was studied by gross dissection and methyl methacrylate corrosion casts. The arterial supply is derived from the left colic artery and cranial rectal artery with the left colic artery supplying approximately the proximal three fourths. Each artery gives off four to eight arcuate arteries that form a series of anastomosing arcades. The arcade pattern continues to form a marginal artery that parallels the long axis of the colon. Small branches from the marginal artery anastomose with adjacent branches to form a secondary arcade. The secondary...
Caecal intussusceptions in horses and the significance of Anoplocephala perfoliata. A caecocaecal intussusception in a pony and a caecocolic intussusception in a horse, both infected with Anoplocephala perfoliata, are described and the relevance of tapeworms in such intestinal disease of horses is reviewed.
Hepaticojejunostomy for treatment of common hepatic duct obstructions associated with duodenal stenosis in two foals. Two female Standardbred foals 2 and 3 months of age were presented with signs of gastroduodenal obstruction that was confirmed with contrast radiography and exploratory surgery. Ventral midline celiotomy was performed, showing stenosis of the duodenum proximal and distal to the hepatopancreatic ampulla. The common hepatic duct, the pancreatic duct, and the sigmoid section of the duodenum proximal to the stenosis were greatly dilated. To bypass the intestinal obstruction, a side-to-side duodenojejunostomy was performed. Obstruction of the common hepatic duct was relieved by side-to-side hepatic...
Abdominal auscultation in the detection of experimentally induced gastrointestinal sand accumulation. A blind study was designed to determine if abdominal auscultation is an effective method for detecting the presence of intestinal sand. Fifteen horses divided into two groups were used in the study. There were seven horses in Group 1 and eight horses in Group 2. All horses were auscultated and determined to be free of sand sounds before initiation of Trial 1. Group 1 horses were given 4.2 g/kg body weight of sand via nasogastric tube using carboxymethylcellulose (CMC) as a suspending agent at 9.0 ml/kg body weight. Group 2 horses were given CMC only. Horses remained in the same group through a...
Evaluation of two techniques for large intestinal resection and anastomosis in the horse. Six normal adult horses had large colon resections at the sternal and diaphragmatic flexures. Stainless steel staples were used to close the stumps of the dorsal and ventral colons in all six. Intestinal continuity was restored with a side-to-side anastomosis of the dorsal and ventral colons. Three of these anastomoses were performed with staples, and three with a double inverting suture pattern. After one month, the horses were surgically reevaluated, and the anastomotic sites were examined. There was no significant difference between the stoma sizes in the two groups. No complications were o...
Ileal impaction in the horse: 75 cases. Records of 75 horses with ileal impactions were examined retrospectively. There was a sex predilection towards mares. Arabians were over-represented compared to the hospital population. The average age was 8.3 years. Abdominal pain was observed in 96% of horses. Nasogastric reflux was present in 56% of horses, small intestinal distention was found on rectal palpation in 96% and an ileal impaction in 25%. Exploratory celiotomy was performed in 69 horses, the mass was reduced by extramural massage in 67 horses, and ingesta was removed via enterotomy in 2. Jejunocecostomies were performed in 47 h...
Biphasic disruption of fasting equine gut motility by dopamine–a preliminary study. Dopamine was infused intravenously (1, 5 and 10 micrograms/kg/min) for 60 min in three fasted ponies. A dose-dependent increase in heart rate occurred that was rapid in onset and termination at the start and end of the infusions, respectively. Dose-dependent changes in gastric and small intestinal motility were observed. An initial marked inhibition of gastric contraction amplitude was followed by a secondary prolonged period of activity. At the same time the small intestine showed a prolonged period of irregular activity (phase II) and a marked increase in the interval between successive phas...
Prokinetic effects of cisapride, naloxone and parasympathetic stimulation at the equine ileo-caeco-colonic junction. The electromyogram of the terminal ileum, the caecum and the proximal right ventral colon was recorded in fasted conscious ponies receiving intravenously equiactive doses of pilocarpine (0.05 mg/kg) and carbachol (0.01 mg/kg) as acetylcholine analogues; cisapride (0.1 mg/kg) and metoclopramide (2 mg/kg) facilitating acetylcholine release from myenteric neurones and naloxone (0.05 mg/kg) as an antagonist of the endogenous inhibitory opioid system. Both cisapride and naloxone induced typical migrating spike bursts in the colon associated with contractions of caecal body and caecal base. Both pil...
Actions of the novel gastrointestinal prokinetic agent cisapride on equine bowel motility. The effect of cisapride was evaluated on the normal fasting bowel motility of four ponies with chronically implanted electromechanical transducers. Cisapride was infused over 60-min periods at 0.05 mg/kg (n = 4), 0.1 mg/kg (n = 5) and 0.25 mg/kg (n = 5). It produced marked and prolonged increases in electrical and mechanical activity at all sites examined. In the stomach there was increased total contraction activity with increased contraction amplitude and a slight reduction in rate. In the small intestine there was an increase in irregular (phase II) activity with an increase in number and a...
Diarrhea associated with sand in the gastrointestinal tract of horses. Four horses with diarrhea had radiographic evidence of large quantities of sand in the gastrointestinal tract. Initially, none of the horses had sufficient fecal sand quantity to suggest sand enteropathy. Diarrhea resolved in all horses within 2 days of oral administration of psyllium hydrophilic mucilloid. Historically, all 4 horses had lost weight or had difficulty maintaining weight. After treatment was administered, the horses either gained weight or were easier to maintain in good condition.
Hematochezia attributable to cranial mesenteric arterial aneurysm with connecting tracts to cecum and ileum in a horse. A cranial mesenteric arterial aneurysm with fistulous tracts to the cecum and ileum was discovered in a Missouri Fox Trotter stallion. The principal clinical sign was hematochezia, observed at 7- and 10-day intervals. The lesion may have been attributable to arteritis caused by fourth-stage larvae of Strongylus vulgaris.
A comparison of enterotomies through the antimesenteric band and the sacculation of the small (descending) colon of ponies. Three pairs of longitudinal enterotomies were performed in the small colon of 10 ponies. Each pair consisted of one enterotomy through the antimesenteric band and one through the sacculation. The ponies were destroyed 96 h after surgery. The enterotomies in the two sites were compared for: speed of surgery, adhesions, bursting wall tension, neovascularisation by micro-angiography, and histological reaction. Enterotomies made through the antimesenteric band were superior because they were quicker to perform, stronger, more accurately apposed, and had less inflammation than those made through th...
Diagnosis and surgical treatment of functional obstruction of the right dorsal colon in a horse. Functional obstruction of the right dorsal colon was found at surgery in a 6-year-old American Saddlebred gelding with a history of anorexia, depression, weight loss, and intermittent colic. Side-to-side anastomosis of the right dorsal colon to the small colon was done to bypass the obstruction. Histopathologic findings of the right dorsal colon and regional colonic lymph nodes were unremarkable. Surgical treatment was successful.
