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.
Davies JV, Gerring EL.Motility patterns in the equine small intestine were investigated in eight ponies. Muscular activity was assessed by means of extramural strain gauge transducers, bi-polar electrodes and in three of the animals, fitted with Thiry-Vella loops, the transit of fluid. Circular muscle contractions were preceded by spiking superimposed on the slow wave and fluid transit in the loops correlated with both these events.
MacKay RJ, French TW, Nguyen HT, Mayhew IG.The effects of large doses of phenylbutazone were evaluated in clinically normal horses. The drug was given to 4 groups of 2 horses each at the rate of 30 mg/kg of body weight, orally, or 30, 15, or 8 mg/kg IV daily for up to 2 weeks. All horses became anorectic and depressed after 2 to 4 phenylbutazone treatments, and the horses given 15 or 30 mg/kg died on or between days 4 and 7 of treatment. A decrease in total blood neutrophil count occurred in all horses, and was associated with toxic left shift in horses given the 2 larger dosage schedules. The horses also had progressive increases in s...
Hackett RP.Nonstrangulated colonic displacement was diagnosed by exploratory celiotomy in 32 horses with acute abdominal pain. Clinical signs progressed slowly and included evidence of mild to moderate abdominal pain, good cardiovascular status, reduced intestinal sounds, and normal peritoneal fluid, and resembled those of colonic impaction. In most horses, rectal palpation supported a diagnosis of colonic obstruction but not a diagnosis of colonic impaction.
Ducharme NG, Fubini SL.Atropine sulfate was given at 2 dosages (0.044 mg/kg, 0.176 mg/kg) to clinically normal ponies in order to evaluate the drug's effect on the gastrointestinal tract. Intestinal motility, as assessed by ausculation of borborygmus, was stopped 30 minutes after injection, but it gradually returned to normal within 12 hours. Signs of abdominal pain developed in 3 of 10 ponies. In 3 clinical cases of gastrointestinal disorder, prior atropine treatment was confusing to the diagnostician and resulted in delayed surgical treatment in 1 case. It was concluded that atropine should not be used for allevia...
Guerrero J, Michael BF, Rohovsky MW, Campbell BP.Eighteen pony foals were experimentally infected with 500 third stage larvae of Strongylus vulgaris at 2 weeks, and at 2, 4, 6 and 8 months after birth. For the duration of the study, all foals were kept in the same pasture with their mothers to allow natural infection with other parasites by exposure to a contaminated environment. Twelve of the foals were utilized in groups of 3 and treated orally five times at two month intervals starting at one month of age with closantel at doses of 5, 10, 20 or 40 mg kg-1. Ten months after birth the foals were necropsied to determine the parasitic burdens...
Hoffmann WE, Dorner JL, Morris H.Antiserum directed against equine intestinal Alkaline Phosphatase (ALP) was produced in rabbits and used to develop a sensitive and quantitative assay for the detection of intestinal ALP in equine serum. This assay was then used to measure the half-life of intravenously injected intestinal ALP and to determine if the intestinal ALP was present in normal horse sera, sera from horses presented for lesions not involving the gastrointestinal tract and sera from horses presented with lesions involving the gastrointestinal tract. The results suggest that intestinal ALP is not likely to appear in equ...
Slocombe JO, McCraw BM, Pennock PW, Vasey J.Twelve pony foals were reared worm-free and inoculated with Strongylus vulgaris. Approximately 8 weeks after they were inoculated, 6 foals were given ivermectin IM at a dosage rate of 200 micrograms/kg of body weight and 6 were given a placebo. All foals were necropsied 35 days after treatment. Ivermectin was 98.9% effective in eliminating later 4th-stage S vulgaris larvae located near the origin of major intestinal arteries and in reducing clinical signs and permitting resolution of lesions associated with verminous arteritis. One pony foal reared on pasture and with evidence of arteritis of ...
Pass DA, Bolton JR.Four cases of chronic eosinophilic gastroenteritis in horses are described. The disease was manifested clinically by weight loss, malabsorption and diarrhea of soft, formless feces. A chronic inflammatory reaction, with diffuse and focal eosinophilic infiltrates, was present in the esophagus, stomach, small and large intestine, and mesenteric lymph nodes. The cause of the lesion was not determined but was thought to the due to an ingested allergen, as the lesion is indicative of an on-going, immediate hypersensitivity reaction. One horse had generalized acanthosis, hyperkeratosis, and ulcerati...
Torbert BJ, Kramer BS, Klei TR.A controlled test was used in ponies to compare the antiparasitic efficacy of ivermectin (22,23-dihydro-avermectin B1) in an injectable micelle solution administered IM with the efficacy of the same drug in an oral paste formulation. Parasite infections were naturally acquired in southern Louisiana. The drug was tested in both formulations at a dosage level of 0.2 mg/kg of body weight. Ivermectin in both formulations tested had an efficacy greater than 98% against Gasterophilus intestinalis and G nasalis larvae. Trichostrongylus axei, Habronema spp, Strongylus vulgaris, S. edentatus, and speci...
Hall GM, Adrian TE, Bloom SR, Lucke JN.Venous blood samples were collected before and immediately after an 80 km ride and a 42 km race. They were analysed for blood glucose and lactate, and for plasma non-esterified fatty acids, insulin, pancreatic glucagon, pancreatic polypeptide, gastrin, gastric inhibitory peptide, somatostatin and vasoactive intestinal polypeptide concentrations. The 80 km ride was associated with marked hypoglycaemia and a slight lactic acidaemia together with an increase in plasma glucagon, somatostatin, pancreatic polypeptide and vasoactive intestinal polypeptide values. The 42 km race produced hyperglycaemi...
Canning JF.Bile flow, during feeding and fasting, was studied in three ponies in which catheters, maintained in the bile duct over 1-2 months, drained all bile continuously. During experiments bile was returned to the small intestine, via a second catheter, by means of a small pump which also measured bile flow rates. The mean +/- S.E. of the mean rate of bile flow in fed ponies with an intact enterohepatic circulation of bile salts was 1.33 +/- 0.10 ml/kg . h, n = 13; mean +/- S.E. of the mean concentration of bilirubin in bile was 10.82 +/- 0.91 mg/dl, n = 13. The effect on bile flow and bilirubin excr...
Barclay WP, Phillips TN, Foerner JJ.Intussusception associated with Anoplocephala perfoliata infection was found in 5 horses. The unusual types of intussusception and the presence of tapeworms at the leading edge of the intussuscipiens suggested tapeworms as the cause of the problem. Lesions attributable to tapeworm attachment on the mucosa were found to fit a mechanical model of intussusception. Treatment of two of the horses and some of their pasturemates with pyrantel pamoate caused elimination of intact tapeworms.
Sellers AF, Lowe JE, Drost CJ, Rendano VT, Georgi JR, Roberts MC.The circular and longitudinal muscle coats of equine "midcolon" were found to be directly electrically coupled. They appear to act in concert, in healthy animals, as a pacemaker in the area of the large colon pelvic flexure, for retropulsive-propulsive myoelectrical events. The retropulsive events keep the cecum and right ventral and left ventral divisions of the colon filled, imposing a delay time for fermentation of cellulose and for bacterial protein synthesis. Point-to-point involvement of adjacent colon sections was slowed by cooling the intestinal contents with no adverse clinical signs....
Wierup M, DiPietro JA.The fecal flora of 56 clinically healthy and 23 sick horses were examined bacteriologically for counts of Clostridium perfringens, molds, coliforms, alpha- and beta-hemolytic streptococci, and microbes belonging to genus Bacillus, as well as for the presence of Salmonella spp. Of the healthy horses, 85.7% had a C perfringens count less than 10(1) colony-forming units/g of feces. Of the healthy horses, lowest counts were found in race-horses. Of the sick horses, equine intestinal clostridiosis was diagnosed in 2 horses with large C perfringens counts (10(4) to 10(7) colony-forming units/g) and ...
Manneveau GB, Robert MP, Tessier C, Bizon-Mercier C.This report describes a rare case of gastric impaction caused by a trichophytobezoar in a foal. This case highlights the difficulty in diagnosing this condition and reports surgical removal via a gastrotomy after failure of medical treatment. Ablation chirurgicale d’un trichophytobézoar gastrique chez un poulain. Ce rapport décrit un rare cas d’obstruction gastrique causé par un trichophytobézoar chez un poulain. Ce cas souligne la difficulté à diagnostiquer cette affection et fait rapport sur l’ablation chirurgicale lors d’une gastrotomie après l’échec du traitement médical...
Trostle SS, Markel MD.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...
Grieve RB, Moore BG, Bradley RE.A critical test was performed to evaluate the anthelmintic properties of an injectable butamisole formulation and to compare the efficiency with that of a commercially available piperazine-thiabendazole anthelmintic. The test was done in 10 horses and 15 ponies with naturally acquired parasitic infections. Butamisole was administered at the dose level of 2.5 or 3.75 mg/kg of body weight by either subcutaneous or deep intramuscular injection. Given at the dose level of 2.5 mg/kg, butamisole was highly effective (99%) against Strongylus vulgaris and moderately effective (49%) against Parascaris ...
Fintl C, Pearson GT, Mayhew IG, Hudson NP.The generation and maintenance of intestinal motility patterns involve the complex interactions of several components including the gastrointestinal pacemaker cells (interstitial cells of Cajal, ICC). Central to ICC function is the generation of rhythmic pacemaker currents, namely slow waves, which represent the rate limiting step for intestinal smooth muscle contractions. Currently, intracellular slow wave activity has not been demonstrated in the equine colon. Objective: To characterise the in vitro myoelectrical activity of the equine pelvic flexure using intracellular recording techniques....
van der Kolk JH, Grinwis GC.A three-year-old pregnant Dutch Warmblood mare was referred to the Department of Large Animal Medicine and Nutrition, Faculty of Veterinary Medicine, because of weight loss for 1 month. The main clinical features were (beside weight loss) moderate ventral oedema, enlarged mesenteric lymph nodes, and uniform thickening of the wall of the jejunum. Haematological evaluation revealed leukocytosis (15.9 G.l-1 with 18% lymphocytes and 1% eosinophils) and a decreased total serum protein and albumin concentration (35 g.l-1 and 36.3% albumin). At necropsy transmural eosinophilic enteritis was found in ...