Topic:Colon
The colon in horses is a significant component of the equine digestive system, responsible for the fermentation and absorption of nutrients from fibrous plant materials. It is a complex organ that plays a key role in the digestion process by hosting a diverse microbiome that aids in breaking down cellulose and other carbohydrates. The colon's structure and function are critical for maintaining overall gastrointestinal health and ensuring the efficient utilization of feed. Conditions affecting the colon, such as impactions, displacements, or inflammation, can lead to colic, a common and potentially serious health issue in horses. This page gathers peer-reviewed research studies and scholarly articles that explore the anatomy, physiology, and pathophysiology of the equine colon, as well as strategies for prevention and management of colonic disorders.
A comparison of the microbiome and the metabolome of different regions of the equine hindgut. The microbiome and associated metabolome of faecal samples were compared to those from the caecum and right dorsal colon of horses and ponies euthanised for nonresearch purposes by investigating the microbial population community structure as well as their functional metabolic products. Through the use of 16S rRNA gene dendrograms, the caecum microbiome was shown to cluster separately from the other gut regions. 16S rRNA gene-based quantitative PCR (q-PCR) also demonstrated differences between the caecum and the other gut regions. Metabolites as identified by Fourier transform infrared cluster...
Effects of ischemia and reperfusion on production of nitrotyrosine, activation of eosinophils, and apoptosis in the large colonic mucosa of horses. To assess the effects of ischemia and reperfusion on indicators of oxidative stress, activation of eosinophils, and apoptosis in the large colonic mucosa of horses. Methods: 40 horses. Methods: In 1 or two 20-cm-long segments of the pelvic flexure, ischemia was induced for 1 or 2 hours followed by no reperfusion or 30 minutes and 18 hours of reperfusion in anesthetized horses. Mucosal specimens were collected before (controls; n = 20 horses) and after each period of ischemia, and full-thickness tissue samples were collected after each period of reperfusion. Sections of colonic tissues were sta...
Effects of flunixin meglumine on recovery of colonic mucosa from ischemia in horses. To examine the effects of flunixin meglumine (FM) on recovery of colonic mucosa from experimentally induced ischemia in horses. Methods: 14 research horses. Methods: Ischemia was induced in the colons of anesthetized horses for 2 hours. Afterward, horses received saline (0.9% NaCl) solution (12 mL, IV, q 12 h; n = 7) or FM (1.1 mg/kg, IV, q 12 h; 7) and were allowed to recover for 18 hours after termination of the ischemic event. Postoperative pain scores were recorded every 4 hours throughout the recovery period. At the end of the recovery period, horses were anesthetized, and ischemic and no...
Effect of live yeast culture supplementation on apparent digestibility and rate of passage in horses fed a high-fiber or high-starch diet. Eight crossbred male horses aged 12 +/- 5 yr and with BW of 305 +/- 18 kg were used in pairs in a 4 x 4 Latin square design with 4 ground and pelleted diets. Each pair included a cecum and right ventral colon-fistulated animal and a cecal-fistulated animal. The 4 horse diets were a high-fiber diet (HF+0) based on dehydrated alfalfa, a high-starch diet based on barley and wheat bran (HS+0), and the HF or HS diets supplemented with Saccharomyces cerevisiae (SC) CBS 493.94 (HF+SC and HS+SC). The probiotic preparation contained 4.5 x 10(9) cfu/g of live yeast mixed with the culture medium, and was...
Distribution of CCR3 mRNA expression in horse tissues. CCL11 (also known as eotaxin) is a very potent and selective mediator of eosinophil migration which exerts its effects through its receptor, CCR3. In this study we report the cloning of an equine CCR3 cDNA sequence and investigation of the localization of CCR3 mRNA expression in horse tissues. Equine CCR3 displayed high levels of sequence identity with CCR3 sequences in other species. RT-PCR analysis revealed the expression of CCR3 in colon, lung and spleen of normal horses. In situ hybridisation experiments indicated that expression of CCR3 mRNA in colon was predominantly in eosinophils and t...
Effect of a preparation of Saccharomyces cerevisiae on microbial profiles and fermentation patterns in the large intestine of horses fed a high fiber or a high starch diet. Eight horses were allotted into pairs consisting of one cecum- and right ventral colon-fistulated animal and one cecum-fistulated animal. They were fed daily at the same level of intake either a high-fiber (HF) or a high-starch (HS) diet without or with 10 g of a Saccharomyces cerevisiae preparation, in a 4 x 4 Latin square design. The HS diet provided a starch overload (i.e., 3.4 g starch x kg(-1) BW x meal(-1)) while maintaining a high amount of fiber intake (i.e., dietary NDF/starch ratio was 1.0). A 21-d period of adaptation to the treatments occurred before cecal and colonic contents were...
[Functional morphology of the large intestinal mucosa of horses (Equus przewalskii f. caballus) with special regard to the epithelium]. The mucous membrane of the caecum and colon ascendens of adult horses was first studied using light and transmission electron microscopy. In the surface epithelium there was an inconspicuous constellation of organelles, otherwise there was a lot of mitochondria as a source of energy for absorptive performances. Moreover, enlarged intercellular spaces exist as an indication of an increased uptake of water and electrolytes. In the basal region of Lieberkühn's crypts there were single enteroendocrine cells and numerous granules in the apical epithelial cytoplasm. The functional meaning of these ...
Methanogenesis in monogastric animals. Studies of methanogenic bacteria present in monogastric animals are still scarce. Methanogens have been isolated from faeces of rat, horse, pig, monkey, baboon, rhinoceros, hippopotamus, giant panda, goose, turkey and chicken. The predominant methanogen in all except the chicken and turkey is species of Methanobrevibacterium. The chicken and turkey harbour species of Methanogenium. In pig the population of methanogenic bacteria is more than 30 times as dense in the distal colon as in the caecum. This finding is in agreement with the finding that the rate of methane production is much higher in...
Laparoscopic anatomy of the equine abdomen. Laparoscopy was performed on 6 horses (2 mares, 2 geldings, 2 stallions) to determine the normal laparoscopic anatomy of the equine abdomen. After withholding feed for 36 hours, horses were examined from the left and right paralumbar fossae, and the visceral anatomic structures were recorded by videotape and photography. One mare developed emphysema located subcutaneously at the primary laparoscopic portal; otherwise, there were no complications. The anatomic structures of diagnostic importance that were observed in the left half of the abdomen were the hepatic duct; left lateral and quadrate ...
Small intestine and small colon neuropathy in equine dysautonomia (grass sickness). The number of neurons in the coeliacomesenteric ganglia and the myenteric and submucosal plexuses of the jejunum, ileum and small colon, and the pathological changes induced in them, were studied in various types of equine dysautonomia. In all forms of dysautonomia, severe and extensive neuron loss and damage occurred in the ileum. In acute and subacute dysautonomia, jejunal neuron loss and damage were severe, but in chronic cases significantly less loss or damage occurred. The damage followed the same pattern in the small colon but it was always less obvious than in the jejunum. The distribut...
Unidirectional fluxes of short-chain fatty acids across segments of the large intestine in pig, sheep and pony compared with guinea pig. Unidirectional fluxes of short-chain fatty acids across pig, sheep and pony caecum, proximal and distal colon were studied under short-circuit current conditions in Ussing chambers. Findings are compared with results from guinea pig. Marked species differences are apparent; highest mucosal-to-serosal fluxes of acetate, propionate and butyrate were seen in guinea pig, lower values in pig and smallest fluxes in sheep and pony. Segmental differences between caecum, proximal and distal colon exist mainly in guinea pig and are less developed in pig, sheep and pony. Inhibition of Na+/H+ exchange by ...
Effects of diet and hindgut defaunation on diet digestibility and microbial concentrations in the cecum and colon of the horse. The effects of diet and hindgut defaunation (removal of protozoa from the hindgut) on diet digestibility (Trial 1) and on total and cellulolytic bacterial and fungal concentrations in the cecum and colon (Trial 2) were investigated. A high-forage (HF) diet, 90% alfalfa hay-10% concentrate, or a higher-concentrate (HC) diet, 60% alfalfa hay-40% concentrate, was limit-fed. In Trial 1, defaunation resulted in a slight decrease in DM digestibility (P < .1) and had no effect on cellulose digestibility. Dry matter digestibility was higher (P < .001) with the HC diet; however, no differences were obs...
Blockade of endotoxin-induced cecal hypoperfusion and ileus with an alpha 2 antagonist in horses. Stimulation of alpha 2 adrenergic receptors inhibits colonic motility and may constrict some peripheral vascular beds. Endotoxemia elicits release of sympathetic neurotransmitters and increases sympathetic nerve activity, which may result in stimulation of alpha 2 adrenergic receptors. The objective of this study was to determine whether blockade of alpha 2 adrenergic receptors would restore cecal motility and blood flow during endotoxemia in horses. Strain-gauge force transducers and ultrasonic flow probes were used to measure cecal and colonic mechanical activity and lateral cecal arterial b...
Effects of xylazine and/or butorphanol or neostigmine on myoelectric activity of the cecum and right ventral colon in female ponies. Effects of xylazine HCl (0.5 mg/kg of body weight, IV) and/or butorphanol tartrate (0.04 mg/kg, IV) or neostigmine methylsulfate (0.022 mg/kg, IV) on myoelectric activity of the cecum and right ventral colon were studied in 4 conscious female ponies. Eight bipolar Ag/AgCl electrodes were sequentially placed on the seromuscular layer of the cecum (6 electrodes) and right ventral colon (2 electrodes). Recordings began 30 minutes before and continued for 90 minutes after drug administration. Each drug or drug combination was studied on 2 occasions in each pony. Two major patterns of coordinated s...
The effects of slow infusion of a low dosage of endotoxin in healthy horses. The effects of slow intravenous (i.v.) infusion of a very low dosage of endotoxin (a cumulative dosage of 0.03 microgram/kg bodyweight [bwt] infused over 60 mins) were evaluated in six conscious healthy horses. Duodenal, right ventral colon, and caecal contractions were detected with strain gauge force transducers. Lateral caecal arterial blood flow was measured using transit time ultrasonic blood flow probes. Duodenal contractile activity was not significantly altered by infusion of endotoxin. In contrast, the contractile activity of the right ventral colon 90 and 270 mins after infusion of e...
Lymphocytic enteritis in a filly. A yearling Hanoverian filly had intermittent colic for 6 weeks, chylous peritoneal effusion, and a firm mass palpable per rectum. Exploratory laparotomy revealed mesenteric lymphadenopathy, adhesion of the mesenteric root to the duodenum and jejunum, distention of the mesenteric veins and lymphatic vessels, and increased jejunal venous pressure. Lesions in the duodenum, jejunum, and colon included infiltration of lymphocytes and plasma cells in the lamina propria.
Megacolon with myenteric hypoganglionosis in a foal. A 6-month-old Clydesdale filly had chronic abdominal distention and intermittent febrile episodes. Abdominal surgery revealed impaction of the right dorsal colon, which was relieved by evacuation of contents through an enterotomy. Four days after surgery, abdominal distention recurred and progressed. The filly was euthanatized. Necropsy revealed the right dorsal colon to be markedly distended with digesta. Microscopically, there was a marked reduction in myenteric ganglion cells in the right dorsal colon and cecum and mild to moderate reduction of myenteric ganglion cells in the left ventral a...
Origin an importance of increased alkaline phosphatase activity in peritoneal fluids of horses with colic. The origin of increased alkaline phosphatase (ALP) activity in peritoneal fluid (PF) of horses with clinical signs of abdominal pain was investigated to determine the usefulness of measuring ALP in PF in the diagnosis of small intestinal injury. The ALP isoenzymes in PF from 10 clinically normal horses and from 50 horses with clinical signs of acute abdominal pain were analyzed for their sensitivities to inhibition by L-phenylalanine, L-homoarginine, and levamisole and to inactivation by heat (56 C, 15 minutes). The enzymes also were discriminated by their patterns of migration during polyacry...
Characterization of equine alkaline phosphatase isoenzymes based on their electrophoretic mobility by polyacrylamide gel disc electrophoresis. Alkaline phosphatase isoenzymes of equine tissues, peritoneal fluid, and serum were characterized by their electrophoretic mobilities, using polyacrylamide gel disc electrophoresis. The alkaline phosphatase isoenzymes in liver, kidney, spleen, small intestine, placenta, bone, small colon, and large colon tissue samples were extracted and separated by electrophoresis. The resulting isoenzyme mobilities and spectrophotometric scans were evaluated for their tissue specificity and for their possible use in determining the tissue contribution of alkaline phosphatase to serum and peritoneal fluid. T...
[Comparative study of the digestion of a complete food in the pony and the rabbit]. A complete pelleted diet (table 1) containing 11 p. 100 of crude protein and 17 p. 100 of cellulose (ADF-lignine according to the method of Van Soest) was distributed to ponies and rabbits. Total digestibilities, partial cumulative digestibilities in different compartments of the digestive tract (stomach, small intestine, caecum, proximal and distal colon) and changes in biochemical composition, measured by pH, VFA, lactic acid and ammonia concentrations, were compared. Total digestibilities (table 2). There was no significant difference in dry matter between the two species. Crude protein dig...
Isoenzymes of equine alkaline phosphatase. Alkaline phosphatase isoenzymes from small intestine, cecum, large colon, small colon, liver, kidney, leukocytes, and serum from ten clinically normal horses were defined by their sensitivities to L-phenylalanine, L-homoarginine, levamisole and heat, and by polyacrylamide gel disc electrophoresis. Readily identifiable isoenzymes occurred in small intestine, granulocytes, kidney, cecum, and large and small colon. By contrast, alkaline phosphatases from liver, lymphocytes, and serum could not be discriminated by this group of tests.
Invagination of the caecum into the colon in a Welsh pony. A chronic wasting disease in a 16 month old Welsh pony filly is described. The animal died 26 days after the onset of illness which commenced with a sub-acute colic and was characterised by progressive loss of appetite and weight. Post-mortem examination revealed a total invagination of the caecum into the colon and it seemed logical to assume this invagination occurred at the start of the illness. A review of the literature showed that total caecal invagination produces 2 distinct clincal syndromes. It can occur either as an acute illness characterised by severe colic and death after about 10...
Diarrhoea in horses associated with ulceration of the colon and caecum resulting from S vulgaris larval migration. The clinical manifestations of a diarrhoeic syndrome of horses with ulceration of the mucosae of the colon and caecum are described. Patients could be divided into three groups according to their presenting symptoms and the disease is probably caused by the thrombo-embolism associated with migrating larvae of Strongylus vulgaris. The differential diagnosis, prognosis and treatment are outlined with particular reference to the use of antithrombotic agents.