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.
Van Hoogmoed LM, Snyder JR, Harmon FA.To evaluate the effect of 2 cyclooxygenase (COX)-2 inhibitors on contractile activity of the circular smooth muscle layer of the equine dorsal and ventral colon. Methods: Samples of the dorsal and ventral colon obtained from 10 healthy horses. Methods: Full-thickness tissue samples were collected from the dorsal colon in the area of the diaphragmatic flexure and the ventral colon in the area of the sternal flexure. Samples were cut into strips oriented along the fibers of the circular muscle layer and mounted in a tissue bath system for determination of contractile strength. Incremental amount...
Koenig JB, Cote N, LaMarre J, Harris WH, Trout DR, Kenney DG, Monteith G.To identify and characterize motilin receptors in equine duodenum, jejunum, cecum, and large colon and to determine whether erythromycin lactobionate competes with porcine motilin for binding to these receptors. Methods: Specimens of various segments of the intestinal tracts of 4 adult horses euthanatized for reasons unrelated to gastrointestinal tract disease. Methods: Cellular membranes were prepared from smooth muscle tissues of the duodenum, jejunum, pelvic flexure, and cecum. Affinity and distribution of motilin binding on membrane preparations were determined by use of 125I-labeled synth...
Lorenzo-Figueras M, Merritt AM.To assess effects of exercise on a treadmill with changes in gastric volume and pH in the proximal portion of the stomach of horses. Methods: 3 healthy adult horses. Methods: A polyester bag of approximately 1,600 mL was placed into the proximal portion of the stomach of each horse via a nasogastric tube. Changes in bag volume, determined by an electronic barostat, were recorded before, during, and after a training session on a treadmill with and without prior withholding of food. In separate experiments, pH in the proximal portion of the stomach was continuously recorded during exercise for f...
Nieto JE, Spier S, Pipers FS, Stanley S, Aleman MR, Smith DC, Snyder JR.To compare effects of a commercially available omeprazole paste and a compounded omeprazole suspension on healing of gastric ulcers in Thoroughbred racehorses in active training. Methods: Randomized controlled trial. Methods: 32 horses with gastric ulcers. Methods: Horses were assigned to 2 groups on the basis of endoscopic gastric ulcer severity. Group-1 horses were treated with omeprazole suspension for 30 days and with omeprazole paste for an additional 30 days. Group-2 horses were treated with omeprazole paste for 30 days and omeprazole suspension for an additional 30 days. Serum omeprazol...
Rabuffo TS, Orsini JA, Sullivan E, Engiles J, Norman T, Boston R.To determine associations between age, sex, or medical treatment and prevalence and severity of gastric ulceration in Standardbred racehorses in training. Methods: Cross-sectional study. Methods: 224 Standardbred racehorses in training. Methods: Gastroscopy was performed on each horse, and mucosal ulceration was graded from 0 (normal mucosa, no lesions) to 3 (extensive, often coalescing, lesions with areas of deep ulceration). Associations between age, sex, or treatment and prevalence and severity of ulcers were evaluated. Results: Prevalence of gastric ulceration was 87%. Although there was l...
Van Hoogmoed LM, Nieto JE, Snyder JR, Harmon FA.To evaluate the efficacy of intraluminal administration of a customized solution during low-flow ischemia and reperfusion in the jejunum of horses. Methods: Segments of jejunum obtained from 13 healthy adult horses. Methods: In isolated segments of jejunum maintained in an extracorporeal circuit, arterial flow was reduced to 20% of baseline for 40 minutes (ischemia) followed by 60 minutes of reperfusion. In 2 groups, a customized solution (concentrations, 12.5 and 25%, respectively) was placed in the lumen prior to low-flow ischemia and maintained during reperfusion. The control group received...
Sutton DG, Preston T, Christley RM, Cohen ND, Love S, Roussel AJ.The aim of this study was to measure the effects of specific commonly used sedative protocols on equine solid phase gastric emptying rate, using the 13C-octanoic acid breath test (13C-OABT). The gastric emptying of a standard 13C-labelled test meal was measured once weekly in 8 mature horses over two 4 week treatment periods. Each horse acted as its own control. In treatment Period 1, saline (2 ml i.v.), xylazine (0.5 mg/kg i.v.), detomidine (0.01 mg/kg i.v.) or detomidine/butorphanol combination (0.01/0.02 mg/kg i.v.) was administered in randomised order after ingestion of the test meal. Duri...
Little D, Blikslager AT.Deal impaction is prevalent in the south-eastern USA, where feeding of Coastal Bermuda hay has been implicated as a risk factor. Alternatively, infection with the tapeworm Anoplocephala perfoliata has been identified as a risk factor for ileal impaction in the UK. We hypothesised that feeding Coastal Bermuda hay and failure to administer routinely an anthelmintic with efficacy against tapeworms would place horses at risk of developing ileal impaction in the USA. Seventy-eight horses, with surgically confirmed ileal impaction and 100 horses admitted for colic that did not have an ileal impactio...
Andrews FM, Reinemeyer CR, McCracken MD, Blackford JT, Nadeau JA, Saabye L, Sötell M, Saxton A.Equine gastric ulcer syndrome (EGUS) represents a major health problem in performance horses. Much debate exists regarding endoscopic gastric ulcer scoring systems and their ability accurately to predict severity or depth of gastric ulcers. The purpose of this study was to evaluate the ability of an endoscopist to count gastric ulcers and predict gastric ulcer severity or depth using 2 endoscopic scoring systems and compare them to the same gastric ulcers see on necropsy and histopathology. Endoscopic examination of the stomach was performed under general anaesthesia on 23 mixed breed yearling...
Campbell NB, Jones SL, Blikslager AT.A potential adverse effect of cyclo-oxygenase (COX) inhibitors (nonsteroidal anti-inflammatory drugs [NSAIDs]) in horses is colitis. In addition, we have previously shown an important role for COX-produced prostanoids in recovery of ischaemic-injured equine jejunum. It was hypothesised that the nonselective COX inhibitor flunixin would retard repair of bile-injured colon by preventing production of reparative prostaglandins, whereas the selective COX-2 inhibitor, etodolac would not inhibit repair as a result of continued COX-1 activity. Segments of the pelvic flexure were exposed to 1.5 mmol/l...
Korolainen R, Ruohoniemi M.In order to investigate the reliability of ultrasonography in revealing intestinal sand accumulations, the cranioventral parts of the abdomen of 32 horses (age 3-20 years) with signs suggestive of gastrointestinal sand were examined radiographically and ultrasonographically. The amount of sand and its localisation, relative to the ventral abdominal wall, were evaluated radiographically and graded (scale 0-4). Motility of the intestine and whether it was lying against the ventral abdominal wall were evaluated ultrasonographically and the findings summed and graded (scale 0-3) to express the lik...
Morton AJ, Blikslager AT.Although short-term survival rates following small intestinal resection reportedly range from 48-88%, there is little information on predicting which horse may or may not survive small intestinal (SI) resection and anastomosis. The aim of this study was to identify factors that contribute to nonsurvival in horses following small intestinal resection. Medical records of horses which recovered from anaesthesia following SI resection were reviewed. Clinical and surgical variables were evaluated for their association with short-term survival using logistic regression and were reported as odds rati...
Lopes MA, Walker BL, White NA, Ward DL.Although large intestine impactions are commonly treated with i.v. fluids combined with the osmotic laxative MgSO4, enteral fluids are less expensive and also appear to be efficacious for impactions. Therefore, this study was conducted to compare the systemic and gastrointestinal effects of enteral fluids with the changes produced by i.v. fluids combined with MgSO4. Four horses with a fistula in the right dorsal colon alternately received both treatments in 2 periods one week apart. Sixty litres of fluids were administered continuously (10 l/h) through a venous catheter or a nasogastric tube. ...
Lorenzo-Figueras M, Jones G, Merritt AM.To assess gastric tone in the proximal portion of the stomach in horses during and after ingestion of 4 diets (2 diets of grain and 2 diets of hay). Methods: 6 adult horses. Methods: A polyester bag with a volume of approximately 1,600 ml was inserted through a gastric cannula into the proximal portion of the stomach of each horse. Internal pressure of the bag was maintained at 2 mm Hg by use of an electronic barostat, and changes in bag volume were recorded before, during, and after horses consumed diets of grain or hay. Each horse was fed 0.5 and 1.0 g of grain/kg and 0.5 and 1.0 g of hay/kg...
Faleiros RR, Macoris DG, Alessi AC, Saquetti CH, Rasera L.To determine the effect of experimental intraluminal distention on microvascular perfusion of the small colon in horses. Methods: 6 mixed-breed healthy horses (mean age [+/- SDI, 9.1 +/- 2 years). Methods: Under general anesthesia, the small colon was exposed by celiotomy and 3 segments were demarcated. In 1 of these segments, intraluminal obstruction was created by placement of a latex balloon inflated to a pressure of 40 mm Hg (obstructed segment). The other segments were the sham-operated segment and the control segment. Microvascular perfusion was evaluated in the mucosal, submucosal, musc...
Loesch DA, Rodgerson DH, Haines GR, Watt BC.To report the postoperative outcome in horses undergoing jejunoileal anastomosis performed with a 2-layer simple continuous technique. Methods: Retrospective study. Methods: 7 horses. Methods: Information regarding signalment, clinical signs, findings at surgery, and postoperative complications was obtained from medical records of horses that underwent exploratory ventral midline celiotomy, small intestinal resection, and jejunoileal anastomosis to correct various small intestinal strangulating lesions. Follow-up information was obtained via telephone conversations with owners or trainers. Res...
Shibahara T, Kuwano A, Ueno T, Anzai T, Kuwamoto Y, Sato H, Maeda T, Ishikawa Y, Kadota K.A 21-month-old Thoroughbred colt showed continuous diarrhea and developmental retardation for 7 months, and was thereafter subjected to euthanasia for necropsy and laboratory examinations. At necropsy, the cecal and colonic mucosae were diffusely rough and hyperemic. Histopathologically, the mucosa and submucosa were edematous and were infiltrated by numerous lymphocytes and macrophages. Meanwhile, three morphological types of Brachyspira antigen-containing spirochetes were found to be numerous in the crypts and in the mucus layer over the epithelium in the cecal and colonic lesions. They were...
Semevolos SA, Ducharme NG, Hackett RP.To compare postoperative complications, short- and long-term survival, and surgical times for hand-sewn end-to-end (EE), stapled functional end-to-end (FEE), and stapled side-to-side (SS) anastomotic techniques for jejunal resection in horses. Methods: Retrospective study. Methods: 59 horses. Methods: Medical records were reviewed to obtain signalment, diagnosis, treatment, and outcome for horses that underwent jejunojejunostomy in our hospital. Only horses that recovered from anesthesia were included in the study. Results: Among the 59 horses, there were 33 EE, 15 FEE, and 11 SS anastomoses. ...
Richter RA, Freeman DE, Wallig M, Whittem T, Baker GJ.To study the functional and structural responses of the right dorsal colon (RDC) of ponies to phenylbutazone (PBZ) in vitro at a concentration that could be achieved in vivo. Methods: 8 adult ponies. Methods: Short circuit current and conductance were measured in mucosa from the RDC. Tissues incubated with and without HCO3- were exposed to PBZ, bumetanide, or indomethacin. Bidirectional Cl- fluxes were determined. After a baseline flux period, prostaglandin E2 (PGE2) was added to the serosal surfaces and a second flux period followed. Light and transmission electron microscopy were performed. ...
Dyer J, Fernandez-Castaño Merediz E, Salmon KS, Proudman CJ, Edwards GB, Shirazi-Beechey SP.Dietary carbohydrates, when digested and absorbed in the small intestine of the horse, provide a substantial fraction of metabolisable energy. However, if levels in diets exceed the capacity of the equine small intestine to digest and absorb them, they reach the hindgut, cause alterations in microbial populations and the metabolite products and predispose the horse to gastrointestinal diseases. We set out to determine, at the molecular level, the mechanisms, properties and the site of expression of carbohydrate digestive and absorptive functions of the equine small intestinal brush-border memb...
Franz S, Baumgartner W.Oesophageal endoscopy in cattle has been rarely reported in the literature. It has, however, been used for many years as an aid to the diagnosis and treatment of illnesses of the upper gastrointestinal tract in small animals and horses. We have assessed the potential value of oesophagoscopy on 120 bovine patients presented at the 2nd Medical Clinic for Ruminants and Swine at the University of Veterinary Medicine, Vienna, over a period of three years. In the course of the study, cattle exhibiting symptoms such as salivation, regurgitation or swelling in the neck region were referred for endosco...
Garrett LA, Brown R, Poxton IR.This study compares quantitatively the microbiota of the gastrointestinal tract of healthy horses with that of horses with equine grass sickness (EGS). Faecal and ileal samples were cultured quantitatively on selective and non-selective media. Confirmed anaerobes were identified to species level. Overall faecal counts gave a ratio of aerobes:anaerobes of approximately 1:1. However, the mean counts in healthy horses of 4.4x10(8) aerobes:3.7x10(8) anaerobes per gram wet weight were different from counts in EGS (means were 10-100-fold higher), with statistically significant differences for the an...
Davidson AJ, Edwards GB, Proudman CJ, Cripps PJ, Matthews JB.The aim of this study was to investigate cytokine expression patterns in the large intestinal mucosa of horses, particularly in diseases associated with inflammation. Many cases of equine colitis remain without a definitive diagnosis and survival rates are poor. In humans, colitis is associated with increased expression of pro-inflammatory cytokines. To examine if similar responses occur in horses, we investigated il -2, il -4, il -5, il -10, tnfalpha, ifngamma and tgfbeta messenger rna expression in large intestinal mucosa. Samples were obtained from animals with large intestinal disease (n=1...
Malone E, Graham L.Choice of an analgesic for gastrointestinal pain requires consideration of the cause of the pain, desired duration of pain relief, need for sedation, and potential side effects and toxicity, particularly in light of other drugs being used and effects on the gastrointestinal tract. It is imperative that close monitoring be continued to ensure that surgical lesions or worsening conditions are detected. Recent research in the field may lead to new drugs, drug combinations, and avenues of treatment that minimize the side effects of these drugs while maximizing their efficacy.
Bennett RC, Steffey EP.REGIONAL ADMINISTRATION: There is limited, but convincing, evidence that epidural administration of morphine and some other mu-agonist opioids consistently relieves regional pain in horses. In addition, this effect is not accompanied by notable undesirable effects. On the other hand, a clinically important analgesic action has not been demonstrated for similarly administered kappa-agonist opioids. There has been little objective data presented to support the analgesic effectiveness of intra-articularly administered opioids in horses. However, the evidence of local opioid receptors legitimately...
Widenhouse TV, Lester GD, Merritt AM.To determine the effect of pH with or without pepsin or taurocholic acid on the bioelectric properties of gastric squamous mucosa in horses. Methods: Gastric tissues obtained from 16 adult horses that did not have evidence of gastric disease. Methods: Bioelectric properties of squamous mucosa were determined, using modified Ussing chambers. Tissues then were exposed to mucosal pepsin (1 mg/ml) or taurocholic acid (2.5 mM) under neutral (pH 74) or acidic (pH 1.7) conditions. Results: Exposure of mucosal sheets to an acidic pH resulted in an immediate and sustained decrease in transmembrane pote...
Freeman DE.Intravenous lidocaine is widely used to prevent or treat postoperative ileus in horses. Clinical studies that support this approach are flawed and contradicted by others. Also, physical obstruction could be more important in causing postoperative reflux than postoperative ileus in the horse. The antiinflammatory properties of lidocaine and the role of inflammation from intestinal handling in the genesis of postoperative reflux are questionable. Because of cost and questionable efficacy of lidocaine, a well-designed clinical trial is required to support its continued use. However, lidocaine cou...
Newman SJ.Equine pancreatic disease is considered rare, and successful treatment is limited. Additionally, antemortem diagnosis of equine pancreatitis is difficult because of the lack of definitive diagnostic tests. Although a paucity of information exists on this entity in the horse, pancreatic disease has typically been shown to be secondary to other gastrointestinal, hepatic, and endocrine conditions. No predisposition based on age, sex, or breed appears to exist, but several conditions predispose a horse to pancreatitis, including grain overload, endocrine disease, and parasite migration. A retrospe...
Rodrigues NL, Doré M, Doucet MY.In order to study the evolution of histopathological and immunohistochemical changes in the gastric mucosa of horses with EGUS (equine gastric ulcer syndrome), a feasible, useful, valid and safe in vivo gastric biopsy technique is required. Objective: To determine the average gastric mucosal healing time following endoscopic gastric biopsy sampling, and evaluate the feasibility, safety and usefulness of samples obtained by this method for histopathological analysis. Methods: Six mature mares from the Faculté de Médecine Vétérinaire research herd were used. Transendoscopic gastric biopsy wa...
Campbell-Thompson ML, Merritt AM.Equine gastric secretion was studied using a gastric cannula model after fasting (basal) and pentagastrin infusion. Gastric secretory rate, pH, osmolality, and electrolyte concentrations and outputs were determined over a 5-h period. Dose-response tests estimated that the maximally effective intravenous dose of pentagastrin was between 3 and 6 micrograms.kg-1.h-1. Basal secretory rate was 278 +/- 29 (SE) ml/15 min, and the pH was 2.00 +/- 0.31. Pentagastrin infusion at 6 micrograms.kg-1.h-1 increased secretory rate to 533 +/- 60 ml/15 min and decreased pH to 1.41 +/- 0.11. Basal gastric acid c...
Kitchen DL, Merritt AM, Burrow JA.To determine gastric secretory responses in horses treated with histamine and to determine the dose of histamine needed to elicit maximal gastric secretion. Methods: 6 adult horses with an indwelling gastric cannula. Methods: Gastric contents were collected in 15-minute periods, and volume, pH, hydrogen ion concentration, hydrogen ion output, sodium concentration, and sodium output were determined. Values were determined without any treatment (baseline), after administration of pyrilamine maleate (1 mg/kg of body weight, i.v., given during a 15-minute period), and during 1-hour infusions of hi...
Knych HK, Stucker K, Gretler SR, Kass PH, McKemie DS.In humans, codeine is a commonly prescribed analgesic that produces its therapeutic effect largely through metabolism to morphine. In some species, analgesic effects of morphine have also been attributed to the morphine-6-glucuronide (M6G) metabolite. Although an effective analgesic, administration of morphine to horses produces dose-dependent neuroexcitation at therapeutic doses. Oral administration of codeine at a dose of 0.6 mg/kg has been shown to generate morphine and M6G concentrations comparable to that observed following administration of clinically effective doses of morphine, witho...
Lester GD, Merritt AM, Neuwirth L, Vetro-Widenhouse T, Steible C, Rice B.To determine the effect of erythromycin lactobionate (ERY) on ileocecocolic myoelectric activity and passage of radiolabeled markers from the cecum. Methods: 6 healthy adult ponies. Methods: After a 12-hour nonfeeding period, 370 MBq of technetium 99m-labeled sulfur colloid in egg albumen and 37 MBq of indium 111-labeled diethyltriaminepentaacetic acid in 60 ml of water were administered directly into the cecal apex. The following drug concentrations were tested: ERY, 0.01, 0.10, 1.0, and 10.0 mg/kg of body weight; ERY, 0.10 mg/kg bolus; and saline (0.9% NaCl) solution, 10 ml. All treatments, ...
Jeffrey SC, Murray MJ, Eichorn ES.Growth factors are important in healing and restoration of injured gastrointestinal tissues and, therefore, we characterised temporally the distribution and density of epidermal growth factor receptor (EGFr) in normal and peptic-injured gastric squamous epithelium of horses. Lesions were induced in the equine gastric squamous epithelium using a feed deprivation protocol that results in prolonged increased gastric acidity. Fifteen mature horses, 9 geldings and 6 mares, age 3 to 20 years, were used and divided into 3 groups: Group 1 (n = 5) were subjected to euthanasia for problems unrelated to ...
van Hoogmoed LM, Boscan PL.Although potent analgesics, opioids decrease intestinal activity, leading to ileus in many species. N-methylnaltrexone (MNTX), an opioid antagonist which does not cross the blood-brain barrier and antagonises the morphine effect on the intestine, directly stimulates motility and restores function without affecting analgesic properties. While its use has been reported in human subjects, there is no information with regard to its usage in the horse. Objective: To determine whether MNTX has an effect on contractile activity of the equine jejunum and pelvic flexure. Methods: Using circular smooth ...
King JN, Gerring EL.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...
Orsini JA, Haddock M, Stine L, Sullivan EK, Rabuffo TS, Smith G.To determine the odds of moderate or severe gastric ulceration in racehorses treated with various antiulcer medications. Methods: Unmatched case-control study. Methods: 798 horses in active race training (252 Thoroughbreds and 546 Standardbreds). Only horses that had been receiving a single antiulcer medication or no antiulcer medication for at least 2 weeks prior to examination were included. Methods: Gastroscopy was performed on each horse by a single individual who was not aware of the horses' antiulcer treatments, and severity of gastric ulceration was scored. Signalment and medication his...
Meuten DJ, Butler DG, Thomson GW, Lumsden JH.Chronic granulomatous enteritis associated with weight loss and hypoproteinemia was identified in 2 horses. Both horses continued to have normally formed feces. Malabsorption of carbohydrate and lipid, with concomitant gastrointestinal protein loss was demonstrated in 1 case. One horse was treated symptomatically and gained 108 kg. In both cases, principal gastrointestinal lesions were partial to total villus atrophy and transmural mononuclear leukocytosis, with lymphocytes and histiocytes predominating. The cause of the condition was not identified in either case.
Maher O, Nieto JE, Stanley SD, Dore E, Snyder JR.To determine the effect of ranitidine on gastric emptying in horses. Methods: 11 adult horses. Methods: In vitro, isolated muscle strips from the pyloric antrum and duodenum of 5 horses were suspended in baths and attached to isometric force transducers. Once stable spontaneous contractions were observed, ranitidine or diluent was added at cumulative increasing concentrations. Isometric stress responses were compared. In vivo, 6 horses were assigned to a group in a prospective randomized crossover study design with a wash-out period of 2 weeks between trials. Ranitidine (2.2 mg/kg) or saline (...
Symm WA, Nieto JE, Van Hoogmoed L, Snyder JR.To describe a novel stapling technique for creation of a complete cecal bypass, without ileal transection in horses. Methods: Experimental study. Methods: Four adult horses. Methods: Through a ventral median celiotomy, jejunocolostomy was made with an intraluminal anastomosis device (ILA-100) and oversewn with a Cushing pattern to reinforce the staple line. Immediately distal to the anastomosis, 4 rows of staples were applied using a thoracoabdominal stapling device (TA-90) to occlude the lumen of the distal jejunum and proximal ileum. Necropsy exams were performed at least 60 days after surge...
Morris DD, Moore JN.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...
Ethell MT, Hodgson DR, Hills BA.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...
Malone ED, Kannan MS, Brown DR.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...
Wolfman EF.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...
Fiege JK, Hackett ES, Rao S, Gillette SC, Southwood LL.To report the results of a survey of opinions on current treatments and estimated outcomes of ascending colon volvulus in horses. Methods: Web-based survey. Methods: American College of Veterinary Surgeons (ACVS) Diplomates (n = 151) who perform gastrointestinal surgery in horses. Methods: ACVS Diplomates with credentials in the large animal specialty obtained by examination in 2010 or earlier (n = 410) were solicited by e-mail to complete a web-based survey designed to determine ascending colon volvulus treatment preferences and outcomes. Results: Responses were obtained from 162 ACVS Diploma...
Orr EL, Staniar WB, Smarsh DN.Various aspects of nutritional management can impact both a horse's gastrointestinal (GI) health and caretaker costs. The objective of this study was to characterize the feeding management and GI issues of horses in Pennsylvania (PA). An online survey was distributed from February 27th to August 31st, 2020. Kruskal-Wallis and Mann-Whitney tests were used to analyze the data. Nonparametric statistics were used when data were not normally distributed. From 470 responses collected, the average horse age was 15.7 ± 7.5 years, and the most common breeds were the Quarter Horse and Thoroughbred. Of ...
MacNicol JL, Murrant C, Pearson W.G's Formula is a novel equine feed additive formulated to promote optimal GI function. The objective of this study was to determine whether the addition of a simulated digest of the composite feed additive G's Formula (FA) would alter the contractile response of gastric smooth muscle to acetylcholine (Ach). Smooth muscle strips from porcine stomachs were excised and attached to an isometric force transducer. An experiment was run to compare tissue contraction between tissue exposed to FA (FA; n = 8, simulated digest of FA was added to the bath) and control tissue (CO; n = 8, no additions m...
Tomlinson JE, Blikslager AT.To determine whether ischemia and flunixin affect in vitro lipopolysaccharide (LPS) absorption in samples of the jejunum of horses. Methods: 12 horses. Methods: Horses were anesthetized, a midline celiotomy was performed, and the jejunum was located. Two 30-cm sections of jejunum (60 cm apart) were selected. One segment was designated as control tissue; ischemia was induced in the other segment for 120 minutes. Horses were then euthanatized. Mucosa from each jejunal segment was mounted on Ussing chambers and treated with or without flunixin. Tissues from 6 horses were used to assess permeabili...
van Harreveld PD, Gaughan EM, Valentino LW.To review the outcome of cases of left dorsal displacement of the large colon (LDDLC) treated with phenylephrine HCl and mild exercise. Methods: Physical parameters, laboratory data, ultrasonographic findings and outcome were analysed in a retrospective study of 12 horses with a confirmed diagnosis of LDDLC which were treated with phenylephrine HCl and mild exercise. Results: Administration of phenylephrine HCl and mild exercise resulted in the resolution of LDDLC in 11 of 12 treated horses. One horse failed to resolve the entrapment and required surgical correction. Conclusions: Administratio...
Lorenzo-Figueras M, Preston T, Ott EA, Merritt AM.To evaluate the effect of ingestion of a high-carbohydrate versus a high-fat meal on relaxation of the proximal portion of the stomach and subsequent gastric emptying in horses. Methods: 6 healthy adult horses. Methods: The study consisted of 2 phases. In phase I, horses were offered a high-fat (8% fat) or a high-carbohydrate (3% fat) pelleted meal (0.5 g/kg) of identical volume, caloric density, and protein content. In phase II, meals consisted of a commercial sweet feed meal (0.5 g/kg) or this meal supplemented with corn oil (12.3% fat) or an isocaloric amount of glucose (2.9% fat). Proximal...
Bauer C, Cirak VY, Hermosilla C, Okoro H.The efficacy of moxidectin was evaluated in young ponies naturally infected with gastrointestinal parasites. Eight animals were treated orally with moxidectin at 0.4 mg/kg bodyweight and eight received only the vehicle. They were all necropsied two weeks later. Faecal samples were examined daily for egg counts and larval cultures. Parasites were recovered from total faecal samples collected daily and from the gastrointestinal tracts at necropsy. Moxidectin reduced the strongyle egg counts by > 99 per cent from three days after treatment but some individuals remained positive for 10 days. Th...
Davidson AJ, Edwards GB, Proudman CJ, Cripps PJ, Matthews JB.The aim of this study was to investigate cytokine expression patterns in the large intestinal mucosa of horses, particularly in diseases associated with inflammation. Many cases of equine colitis remain without a definitive diagnosis and survival rates are poor. In humans, colitis is associated with increased expression of pro-inflammatory cytokines. To examine if similar responses occur in horses, we investigated il -2, il -4, il -5, il -10, tnfalpha, ifngamma and tgfbeta messenger rna expression in large intestinal mucosa. Samples were obtained from animals with large intestinal disease (n=1...
Lem MF, Vincent KP, Pone JW, Joseph T.It is important to understand the biology and health impact of parasites affecting horses in the Western highlands of Cameroon. Objective: to evaluate the prevalence and intensity of infection of gastrointestinal helminths in these animals. Methods: A total of 894 horses (367 males and 527 females), and aged ≤1 to ≥7 years old were examined. A parasitological investigation of faeces was carried out using two techniques: concentration method of Full Born Willis (flotation in saturated solution of sodium chloride) and Mc Master Technique. Conclusions: From the results the overall prevalence ...
MacAllister CG, Sangiah S.Thirty young ponies were examined endoscopically for evidence of gastric ulceration. Seven ponies had noninduced gastric ulcers present at the initial examination and were eliminated from the study. In an attempt to induce gastric ulcers experimentally, flunixin meglumine (1.1 mg/kg of body weight, IM, q 8 h) was administered for 7 days to the 23 ponies with endoscopically normal gastric mucosa. During the 7 days of flunixin administration, 11 ponies developed gastric ulcers that were appropriate for study. The 11 ponies were randomly allotted to 2 groups. Group-A (n = 5) and group-B (n = 6) p...
Jacobs RD, Gordon MBE, Vineyard KR, Keowen ML, Garza F, Andrews FM.Low gastric pH for extended periods of time can increase the risk of gastric ulceration in horses. Therefore, nutritional interventions that buffer stomach acid may be helpful to decrease ulcer risk. The objective of this trial was to evaluate whether the incorporation of calcified Lithothamnion corallioides and Phymatolithon calcareum (Calmin; Celtic Sea Minerals, Cork, Ireland) into an equine ration would buffer equine gastric juice. Nine mature, Thoroughbred-cross horses, including 6 geldings and 3 mares (524 ± 49 kg) were housed in stalls and fed 2 kg/day of a texturized concentrate (Pu...
Woods LW, Filigenzi MS, Booth MC, Rodger LD, Arnold JS, Puschner B.Three horses died as a result of eating grass hay containing summer pheasant's eye (Adonis aestivalis L.), a plant containing cardenolides similar to oleander and foxglove. A 9-year-old thoroughbred gelding, a 20-year-old appaloosa gelding, and a 5-year-old quarter horse gelding initially presented with signs of colic 24-48 hours after first exposure to the hay. Gastrointestinal gaseous distension was the primary finding on clinical examination of all three horses. Two horses became moribund and were euthanatized 1 day after first showing clinical signs, and the third horse was euthanatized af...
