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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 rupture in horses: 50 cases (1979-1987). A computer-based search was conducted of medical and necropsy records of horses admitted to the teaching hospital from Jan 1, 1979, to Dec 31, 1987, to obtain the records of all horses admitted to the hospital for colic and subsequently found to have gastric rupture. Fifty cases of gastric rupture were found. The records were reviewed to obtain data regarding peritoneal fluid analysis. Cell counts of these samples were often erroneous because debris and clumps of bacteria were counted when most WBC were lysed. A cross-sectional study of gastric rupture cases versus all other colic cases regard...
Leiomyosarcoma of the duodenum in two horses. Two horses affected by chronic, intermittent colic were found, at post-mortem examination, to have localized annular thickening of a segment of the duodenum. Histological examination of the lesion in both cases revealed a tumour composed of bundles of oval or spindle-shaped cells that stained as muscle with van Gieson stain. The histological diagnosis was leiomyosarcoma. The tumour had caused partial bowel obstruction in both horses.
Pharmacokinetic studies of cimetidine hydrochloride in adult horses. Histamine type II (H2) antagonists inhibit gastric acid secretion and are useful in treating gastric and duodenal ulcer disease. To provide some information on the pharmacokinetics of the H2 antagonist cimetidine, adult horses were given 3.3 mg/kg cimetidine intravenously (iv) or 3.3 and 10 mg/kg orally. Plasma cimetidine concentrations after 3.3 mg/kg orally were too low to measure. Following 3.3 mg/kg iv, cimetidine displayed two-compartment characteristics with a t1/2 of 0.083 +/- 0.039 h and t1/2 of 2.23 +/- 0.64 h. The total body clearance was 0.443 +/- 0.160 litre/h/kg and the mean resid...
Molecular forms of gastrin in antral mucosa of the horse. The predominant form of gastrin in the antral mucosa of the stomach of virtually all species previously examined is the 17 amino acid peptide little gastrin (G17). This report describes the occurrence in equine antral mucosa of an immunoreactive form of gastrin with elution properties on Sephadex G-50 superfine similar to human unsulfated big gastrin (G34-I). This putative equine big gastrin was a major component of the gastrin immunoreactivity present. A second peak of activity in equine antral mucosa eluted in an identical manner to human little gastrin (hG17-I). Inhibition curves of equine ...
Prevalence of gastric lesions in foals without signs of gastric disease: an endoscopic survey. Gastroendoscopic examinations were conducted on 75 Thoroughbred foals aged two to 85 days on seven breeding farms in England and Ireland. The foals showed no signs of gastric disease. There was no significant difference between lesion prevalence in foals in England (16 of 28 foals; 57 per cent) or Ireland (22 of 47 foals; 47 per cent). Neither was there any sex predilection (18 of 36 males; 20 of 39 females). Lesions were most prevalent in foals under 10 days old (8 of 9) and least prevalent in foals older than 70 days (3 of 10). Lesions occurred most frequently in the squamous mucosa immediat...
[The occurrence of feed-induced stomach ulcers in horses]. Ponies were fed hay (n = 21) or mixed feed (n = 27; 128 g crude protein, 175 g crude fibre/kg dry matter) for at least 14 days (treatment against parasites with ivermectin before the experimental period). The feeding level was 18 g dry mater/kg body weight/day. After the feeding period (the experiments were conducted to investigate the water and electrolyte content of the alimentary tract in dependence on feed, feeding time and physical exercise) the ponies were slaughtered and the stomachs were visually controlled for the occurrence of ulcers. In the hay group no gastric ulcers were observed,...
Ileocecal intussusception in horses: 26 cases (1981-1988). The case records of 26 horses with ileocecal intussusception over a 7-year period were reviewed to determine clinical features of the disease and response to treatment. The median age of horses with ileocecal intussusception was 1 year and ranged from 2 weeks to 19 years. There was no apparent gender or breed predisposition to this disease. An acute form of ileocecal intussusception was diagnosed in 19 horses with signs of moderate to severe abdominal pain of less than or equal to 24 hours' duration, and a chronic form was diagnosed in 7 horses with signs of intermittent, mild to moderate abdo...
Microvascular circulation of the ascending colon in horses. Microvascular circulation of the ascending colon in healthy horses was studied using microangiography, light microscopy, and scanning electron microscopy. The pelvic flexure with 30 cm of ventral and dorsal colon attached was removed from 14 adult horses immediately after horses were euthanatized. The lumen was flushed with warm water, and this section of the ascending colon was placed in a 37-C bath of isotonic NaCl. In sections from 8 horses, colic vessels were perfused with a radio-opaque medium for microangiography. After angiographic evaluation, tissue sections were prepared for light mic...
Effects of misoprostol and omeprazole on basal gastric pH and free acid content in horses. The basal gastric pH and free acid contents from five young adult healthy horses were determined at one hour intervals for eight hours. The basal gastric pH and free acid contents varied from 1.63 +/- 0.06 to 1.97 +/- 0.11 and 26.42 +/- 4.14 to 17.92 +/- 5.28 mmol litre-1, respectively. Misoprostol, a methylester analogue of prostaglandin (5 micrograms kg-1, orally) produced a time-dependent increase in the basal gastric pH to above 3.5 (P less than 0.05) at three, four and five hours after administration with a concomitant reduction of 80 to 90 per cent in the basal gastric free acid contents...
Further experiences with non-surgical correction of nephrosplenic entrapment of the left colon in the horse. Non-surgical correction of nephrosplenic entrapment of the left colon was attempted in 27 cases. In two cases the method failed and a laparotomy was necessary. Two other horses had a recurrence, one of which underwent laparotomy because of torsion of the caecal body.
Internal parasites of horses on mixed grassveld and bushveld in Transvaal, Republic of South Africa. Between 1980 and 1982, the gastrointestinal tracts of 17 horses which had been grazing on mixed grassveld at Potchefstroom and bushveld at Onderstepoort in the province of Transvaal, Republic of South Africa, were examined at necropsy and processed for parasite recovery. The large strongyles and their prevalences were as follows: Strongylus vulgaris and associated lesions (88-94%), Strongylus edentatus (24%), Strongylus equinus (30%), Triodontophorus nipponicus (35%) and Craterostomum acuticaudatum (18%). The seven most prevalent and abundant cyathostomes collected were Cylicostephanus longibu...
Endoscopic appearance of gastric lesions in foals: 94 cases (1987-1988). 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...
Histochemistry of complex carbohydrates in the horse duodenal gland. Complex carbohydrates were examined in glandular cells of the horse duodenal gland by using lectin histochemical techniques. In the horse, the duodenal gland was distributed in the area from the uppermost part of the small intestine to a point about 6m caudal to the pylorus. It consisted of two types of cells, mucous and serous cells. The former was found in glands distributed almost all over this part, but the latter was present in glands distributed restrictedly to the uppermost part of the small intestine at a point about 10 cm caudal to the pylorus. The cytoplasm of the mucous cell contain...
Fluorometric evaluation of large and small intestinal ischaemia in the horse. Arteriovenous (ischaemic strangulating obstruction, ISO) and venous obstructions (haemorrhagic strangulating obstruction, HSO) were created for 70 min in the small intestine of eight anaesthetised horses, and ISO was created in four horses for 2 h and four horses for 3 h at the sternal and diaphragmatic flexures of the large colon. Five minutes following release of the occlusions, sodium fluorescein 20 per cent (0.5 mg/kg bodyweight intravenously) was administered. Serial quantitative measurements of serosal surface fluorescence of the injured segments and a control segment were made at 2, 10,...
Large intestinal capacity, retention times, and turnover rates of particulate ingesta associated with extensive large-colon resection in horses. Fecal excretion of a particulate marker, ytterbium (Yb), was evaluated in 9 horses before surgery and 3 weeks, 3 months, and 6 months (4 trials) after sham-operation (group 1; n = 3) or extensive large colon resection (group 2; n = 6). Fecal excretion curves of total Yb excretion, loge Yb excretion, % Yb excretion, loge % Yb excretion, and cumulative % Yb excretion were evaluated, and kinetic analysis was performed on the loge Yb excretion curves to detect mixing pools and to calculate the fractional rate of particulate passage, turnover rate, and pool size. Calculations were performed to dete...
Upper gastrointestinal surgery for ulcer disease in foals. The goals of surgical therapy in foal gastroduodenal ulcer disease are the elimination of abdominal pain, healing of mucosal ulcerations, and prevention of complications. Gastrojejunostomy has been used with success in both pyloric and duodenal ulcerations that have progressed to gastric outflow obstruction. Gastrojejunostomy has resulted in rapid healing of gastritis and esophagitis and resolution of aspiration pneumonia and biliary stasis without recurrence of duodenal ulceration.
Normal intestinal motility. Perhaps because of the inherent difficulty in using horses as experimental animals, only a relatively small amount of data is as yet available regarding normal equine gut motility. However, it is clear that the horse is fundamentally similar to other mammalian species studied. The neural and humoral control of gut activity requires much exploration; it is likely that, in the horse, some of this information will be derived during the investigation of the effects of various substances that might have clinical relevance. This is alluded to in the chapter that follows (The Effects of Pharmacologic...
Determination of intestinal viability. Operations for intestinal ischemia are frequently done by veterinarians. In equine surgery those conditions commonly producing ischemia are intussusception, volvulus, bowel obstructions, and incarcerated hernias. In an attempt to predict intraoperative bowel viability after the restoration of circulation, a variety of adjuvant methods have been investigated. There is little question that of the techniques currently available, sodium fluorescein injected intravenously approaches the ideal in predicting nonviability in humans and in most animal models. Furthermore, it is safe, takes little opera...
Surgical diseases of the equine cecum. Cecal impaction and cecal perforation, the two most common equine cecal diseases, are thought to develop after slowing or interruption of a single progressive motility pattern, which begins in a pacemaker area near the apex, occurs once every 3 minutes, and propels ingesta from the cecum to the right ventral colon. Rectal examination in horses with cecal impaction is the most useful technique to grade the severity of the condition. Medical treatment is undertaken if the impaction is judged to be mild to moderate. Surgical correction of cecal impaction in severe cases requires a ventral midline...
Effects of pharmacological agents on gastrointestinal motility. The control mechanisms of gastrointestinal motility are complex. Extrinsic neurohormonal effects modulate an intrinsic system, often called the "gut brain," composed of nervous and neuropeptide components. To exert pharmacologic influence on GI motility, use is made of agents that mimic the external control system. Agents that stimulate opioid receptors, block adrenoceptors, block or facilitate acetylcholine action, or antagonize the action of prostaglandins are used to effect changes in GI motility. The major indications for pharmacologic intervention are to increase motility in constipation,...
Use of a linear stapling device to construct an inverted, triangulated, end-to-end anastomosis of the equine jejunum. An inverting, triangulated, stapled, end-to-end anastomosis technique was evaluated in the jejunum of four horses. None of the horses showed evidence of gastrointestinal disturbance after surgery; however, stricture and adhesion formation were pronounced in three animals examined 10 days, one month, and two months after surgery. The animal examined four months after surgery had no adhesions present at the anastomosis, and only mild narrowing of the intestinal lumen. Histologic examination of the anastomoses showed lack of a normal mucosal lining in some examined sections up to two months posts...
Postprandial serum gastrin concentrations in normal foals. Postprandial gastrin concentrations were assayed in serum samples from a group of six foals at one day, one week, one month and three months of age. Before sampling, each foal was prevented from feeding for 2 h and was then allowed to suck for 15 mins. Blood samples were taken at the start of the meal and at 30 min intervals for the next 3 h. Feeding increased serum gastrin concentrations at one day, one week and one month, with the greatest increases detected at one day. Mean pre-feeding gastrin concentrations were 25.2 +/- 2.3 pg/ml at one day, 22.8 +/- 3.9 pg/ml at one week, 15.2 +/- 2.3 pg...
Treatment of gastric ulcers in horses with histamine type 2 receptor antagonists. Of 55 horses treated with histamine type 2 (H2) receptor antagonists for gastric ulcers, 32 were examined by gastroendoscopy before and after treatment. Distribution and severity of lesions in the squamous fundus (sf), margo plicatus (mp), glandular fundus (gf), lesser curvature (lc) and cardia (car) were recorded. Severity of the lesions was scored 0-4 (0 = no lesions, 4 = most severe). On initial examination, lesions were most frequently observed at the mp (28/32) and least frequently observed in the gf (5/32). There was endoscopic confirmation of improvement in lesion scores in each region,...
A device and technique for gastrointestinal lavage in the horse. A device and technique for intra-operative gastro-intestinal lavage was developed to remove ingesta from the stomach, large intestine and caecum of horses. The Gastro-Intestinal Lavage System (GILS) is composed of a nozzle connected to both water under pressure and suction. Water jets across an intake portal in the nozzle, breaks up food and debris within the nozzle and is evacuated under negative pressure into the aspirating tube which is connected to a collection drum. The GILS nozzle was introduced at the pelvic flexure through a sterile enterotomy cuff and plastic sleeve. Water was first a...
The effect of Strongylus vulgaris larvae on equine intestinal myoelectrical activity. The myoelectrical activity of the ileum, caecum and large colon was monitored from Ag-AgCl bipolar recording electrodes in four conscious 'parasite-naive' weanling foals. All foals were inoculated with 1000 infective 3rd-stage Strongylus vulgaris larvae and alterations to the myoelectrical activity observed. The frequencies of caecal and colonic spike bursts increased significantly in all post infection periods coinciding with assumed larval penetration into the intestinal mucosa and migration through the vasculature. Peaks in caecal and colonic activity occurred at Days 1 to 5 post infection....
Observations on the colic motor complex in a pony with a small intestinal obstruction. Characteristic motility patterns were seen throughout the gastrointestinal tract in a pony prepared chronically with electromechanical recording devices after developing a simple obstruction of the small intestine. Gross distension of the stomach with fluid produced loss of gastric contractile activity and a chaotic electrogram. These changes were reversed instantaneously when the stomach was decompressed. In the jejunum, proximal to the obstruction, the unique 'colic motor complex' was observed with contractions of longer duration arranged in characteristic pulses of activity. The left dorsal...
Gastric ulcers in horses: a comparison of endoscopic findings in horses with and without clinical signs. Gastroendoscopic examinations were performed on 187 horses, ranging from one to 24 years. Eighty-seven horses had clinical problems including chronic, recurrent colic for seven or more days (25), one or more episodes of colic within the previous seven days (13), or acute colic (10), diminished appetite (53), poor bodily condition (40), and/or chronic diarrhoea (9). One hundred horses that had no signs of gastrointestinal problems were examined as part of a gastroendoscopic survey. Lesions observed in the squamous fundus, squamous mucosa adjacent to the margo plicatus along the greater curvatur...
