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.
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...
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.
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...
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.
Gastric hyperplastic polyp in a horse. An unusually large, pedunculated (20 cm long) mass arising the gastric pylorus which produced complete obstruction of the proximal duodenum and severe gastric distension was found in a 13-year old castrated male Arabian horse. The histological diagnosis was gastric hyperplastic polyp, which has not been reported previously in the horse. The clinico-pathological findings in this horse are compared with hyperplastic (inflammatory) gastric polyps of man.
The role of intestinal microflora in the metabolism of trichothecene mycotoxins. The role of faecal and intestinal microflora on the metabolism of trichothecene mycotoxins was examined in this study. Suspensions of microflora obtained from the faeces of horses, cattle, dogs, rats, swine and chickens were incubated anaerobically with the trichothecene mycotoxin, diacetoxyscirpenol (DAS). Micro-organisms from rats, cattle and swine completely biotransformed DAS, primarily to the deacylated deepoxidation products, deepoxy monoacetoxyscirpenol (DE MAS) and deepoxy scirpentriol (DE SCP). By contrast, faecal microflora from chickens, horses and dogs failed to reduce the epoxide ...
Detection of endotoxin in cases of equine colic. The Limulus amoebocyte lysate assay was used to test for the presence of endotoxin in 37 clinical cases of equine colic. Positive plasma titres were detected in 10 cases and the presence of endotoxin was significantly correlated with a high heart rate, a high packed cell volume and a poor prognosis. High levels of endotoxin were detected in gut contents taken from several sites in the gastrointestinal tract of normal horses.
Enumeration of anaerobic bacterial microflora of the equine gastrointestinal tract. Samples from the duodenum, jejunum, and ileum, as well as from the cecum and colon, were obtained from 11 mature grass-fed horses. Viable counts of total culturable and proteolytic bacteria were made on habitat-simulating media containing 40% clarified ruminal fluid. The mean pHs in the duodenum, jejunum, and ileum were 6.32, 7.10, and 7.47, respectively; the mean pH decreased to 6.7 in the hindgut. The acetate concentration increased along the length of the small intestine and was the only volatile fatty acid present in this gut segment. Molar proportions of acetate, propionate, and butyrate ...
The arrangement of the muscle layers at the equine ileocaecal junction. The muscle layers of the ileocaecal junctions of horses (n = 18), plains zebras (Equus burchelli antiquorum) (n = 3), mountain zebras (Equus zebra zebra) (n = 2), and a donkey were examined macroscopically and microscopically. The muscular tunic of the ileocaecal papilla was made up of 3 layers: an innermost circular layer which was a continuation of the circular muscle of the ileum, a central longitudinal layer which was a continuation of one part of the longitudinal layer of the ileum and an outermost layer, composed of two collateral semicircular lips, formed by the circular layer of the ca...
Examination of the horse with colic. The purpose of this detailed description of the clinical examination of the colic patient is to arrive at a specific diagnosis. However, this is hardly ever possible, but the practitioner should be in the position to establish the suspicion of an intestinal obstruction or to rule out its presence during the course of the development. Single clinical findings should not be interpreted in isolation but in relation to one another, so that a false diagnosis is not made. All clinical findings should be documented, so that when repeated examinations are carried out, findings can be compared with one...
Initial treatment of colic. This article discusses some of the rationales for the medical management of colic during the initial treatment period. The issue of colic pain control and the masking of clinical signs that may indicate severe gastrointestinal disease is addressed. Therapeutic considerations related to dehydration, metabolic imbalances, hemostatic disorders, antimicrobial therapy, fecal consistency, gastrointestinal decompression, and regulation of intestinal motility are reviewed.
Selected aspects of the clinical pharmacology of visceral analgesics and gut motility modifying drugs in the horse. Comparison of the visceral analgesic effects of xylazine, morphine, butorphanol, pentazocine, meperidine, dipyrone, and flunixin in a cecal distention model of colic pain indicated that xylazine produces the most relief from abdominal discomfort. Repeated administration of xylazine may reduce visceral pain so effectively that the seriousness of abdominal disease is obscured. Xylazine decreased propulsive motility in the jejunum and pelvic flexure of healthy ponies. Morphine and butorphanol also gave relief from visceral pain in the cecal distention model. Morphine may inhibit colonic, and buto...
Alternative diagnoses in the colic patient. Despite clinical signs compatible with obstruction or ischemia of the gastrointestinal tract, the clinician occasionally is unable to identify a gastrointestinal cause for colic. In this article, disorders not originating from obstruction or ischemia of the gastrointestinal tract but causing real or apparent abdominal pain are presented as alternative causes of colic. In addition, colic of gastrointestinal origin may be the primary inciting factor or a secondary complication of an alternative disorder, causing colic-like signs. Recognition of alternative diagnoses relies on a thorough and cons...
Equine large intestinal volvulus. A review of 124 cases. The average age of 122 horses with ascending colon volvulus was 6.6 +/- 0.4 years. Gastric reflux was a presenting sign in 35% of the cases. Peritoneal fluid protein levels had a mean of 2.54 +/- 0.14 g/dl and 20 horses had grossly normal peritoneal fluid at the time of presentation. Ascending colon volvulus was most commonly found at the level of the cecocolic fold with the initial ventral colon movement in a dorsomedial direction about the ascending mesocolic axis. The overall survival rate was 34.7% with a recurrence rate of only 4.9%.
Sudden and unexpected death in horses and ponies: an analysis of 200 cases. An analysis was made of the causes of death in horses and ponies over one year of age which died suddenly (Group 1) or were found dead but were considered normal when last seen (Group 2). There were 49 animals in Group 1. Thoroughbreds were overrepresented, but there were no ponies in this group. No cause of death was found in 30.6 per cent of cases and 16.3 per cent died from each of the following causes: haemorrhage in the respiratory system, central nervous system, and adverse drug reactions. Cardiovascular lesions were the cause of death in 14.4 per cent and the remaining 3.1 per cent had ...
Septicemic salmonellosis and suspected phenylbutazone toxicosis in an aged pony. A 16-year-old pony with signs of intermittent abdominal pain was treated with phenylbutazone in excess of the recommended dosage. Endoscopy revealed ulceration of the esophagus, stomach, and proximal portion of small intestine. The pony developed diarrhea. Salmonella typhimurium was isolated from the blood and feces. Treatment included fluids, trimethoprim-sulfadiazine, sucralfate, and ranitidine hydrochloride. The diarrhea resolved, as did the gastrointestinal ulceration. This case was unusual because septicemia with salmonellosis is an uncommon finding in adult equids. Also, complications co...
Duodenal impaction in a horse. An 8-cm compressed mass of dry cracked corn was found obstructing the duodenum of a horse with signs of colic. The mass was manipulated aborally and removed through jejunal enterotomy. The horse recovered and the impaction did not recur.
Ciliated protozoa in the colonic wall of horses. Ciliated protozoa of several morphological types were found in the colonic tissue of 8 horses, mostly immature Standardbreds. Most of the protozoa observed appeared similar to those normally found as commensals in the equine large intestinal lumen. In all cases, organisms were located in the lamina propria; organisms were also found in the submucosa of 2 horses. The association of colonic disease with the presence of intramural ciliates was unclear.
Survival rates and post-operative complications after equine colic surgery. A retrospective analysis of 74 cases that underwent surgery for colic was undertaken to determine short and long term survival rates and the incidence of post-operative complications. In 28 cases colic was related to small intestinal lesions and in 46 cases to large intestinal lesions. Pre-operative packed cell volume and heart rate were found to be inversely related to short-term survival. Twenty-five horses (34%) recovered from surgery and were discharged. Of 18 of these cases with available histories, 6 subsequently had one or more episodes of colic since surgery of which 5 eventually died ...
Megaesophagus and aspiration pneumonia secondary to gastric ulceration in a foal. 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 ...
Morphologic effects of experimental distention of equine small intestine. The morphologic effects of induced intraluminal hydrostatic pressures (IHPs) of 0, 9, and 18 cm H2O were evaluated in 33 isolated equine jejunal segments. Fifteen segments were distended with Tyrode's solution for 1 hour and nine segments for 4 hours. Tyrode's solution was added as needed to maintain the prescribed pressures. Nine other segments were left undisturbed for 4 hours after the initial distention period. On decompression of the intestinal segments, progressive peristaltic contractions resumed in all segments. Evaluation of intestinal sections by light microscopy and transmission ele...
[The anterior enteritis syndrome in the horse]. The anterior enteritis syndrome in the horse is reviewed with reference to the aetiology, pathogenesis, clinical findings, laboratory findings, diagnosis, treatment, prognosis and post mortem findings.