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Radiography and ultrasonography are the most important imaging modalities to evaluate the small intestine of veterinary patients because they are noninvasive and inexpensive and often can be performed without sedation or anesthesia. 1

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in American Journal of Veterinary Research

be caused by masses (such as those caused by fat necrosis) impinging on the intestine. Recently, trichobezoar (also called hair ball) was reported as the cause of physical intraluminal obstruction in the small intestine of 2 young calves. 3 The

Full access
in Journal of the American Veterinary Medical Association

cm for the pancreas, small intestine, and lymph node; 4.5 cm for the liver, renal cortex, and medulla), time gain compensation, overall gain, and focal zones. Two focal zones were placed at the level of or just below the organ imaged for each organ

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in American Journal of Veterinary Research

processes of the vertebrae to the linea alba on the right side was examined using a 5.0 MHz linear or convex transducer. The appearance of loops of small intestine and their diameter, contents, and motility were assessed. In addition, the appearance

Open access
in Journal of the American Veterinary Medical Association

Summary

The microvascular anatomic features of the small intestine was described by correlating results of microangiography, light microscopy, gross studies, and scanning electron microscopy of vascular replicas in 14 horses. After heparinization, the horses were euthanatized, a length of jejunum was transected, and blood was flushed free of the circulation, using isotonic NaCl solution. In six horses, the circulatory system was perfused with a modified radiopaque medium and evaluated radiographically. These sections were then evaluated by standard histologic methods. Sections from 8 horses were perfused with 1 of 2 types of plastics and studied grossly or by scanning electron microscopy.

The margined arterial arcade gives rise to vessels that enter the jejunum at the mesenteric angle. These vessels penetrated either directly, by branching and entering on both sides of the mesenteric angle, or supplying only 1 side of the mesenteric angle. All these vessels continued in the submucosa branching extensively, forming a submucosal plexus. This submucosal plexus supplied the tunica muscularis, tunica serosa, and the mucosa. Vessels within the 2 muscle layers ran parallel to the muscle fibers and, consequently, perpendicular to each other. The arterial supply to the mucosa penetrated the muscularis mucosae and branched to supply 2 mucosal capillary networks. An eccentrically placed arteriole penetrated the base of the villus and spiralled to the tip where it "fountained" into a mesh-like capillary network, which descended peripherally in the villus to drain via 1 to 3, but most commonly 2 venules. Venules from adjacent villi united and drained via the submucosal veins. The second capillary network supplied the glands of the intestinal crypts. The capillary network around adjacent glands anastomosed just below the luminal surface. There were connections between this network and the base of the villus capillary network. Drainage of the glandular capillary network was through these connections and through the villus venules. There was no evidence of arterovenous anastomoses.

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in American Journal of Veterinary Research

Summary

Diamine oxidase (dao), an enzyme of small intestinal origin, is released from mucosal storage sites by IV administration of heparin, to yield the plasma postheparin dao (phd) curve. The phd curve is diminished when mucosal surface area is lost, and baseline (without heparin) plasma dao activity increases when mucosal storage sites are damaged. Plasma dao activity was measured after 2 doses of heparin were administered iv in healthy, conscious horses. In anesthetized horses, the phd curve was studied: during sham small intestinal surgery, and during venous strangulation obstruction (vso) of the distal 50% of the small intestine. In a third group of anesthetized horses, baseline plasma dao activity (without heparin) was measured during vso of the distal 50% of the small intestine for 90 minutes, followed by reperfusion for 90 minutes.

Postheparin plasma dao curves in conscious horses were similar to those reported in other species. Horses with vso had a similar phd curve as did sham-operated controls at all times, except at 15 minutes, when plasma dao activity was significantly (P < 0.05) greater in the vso group. Horses with vso and reperfusion had no change in baseline plasma dao activity throughout the study. Peritoneal fluid dao activity remained low throughout the study, but increased slightly in horses with vso that received heparin, possibly because of dao from extravasated blood in the peritoneal fluid.

Results indicated that the plasma dao response to iv administered heparin in horses is similar to that in other mammals, but, unlike other species, baseline and postheparin dao activities did not change as expected after small intestinal vascular obstruction and mucosal injury. There may be additional sources of dao in horses, the type of injury induced was not of sufficient magnitude to affect storage sites of dao, or the circulatory changes induced by vso might have altered tissue delivery of heparin.

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in American Journal of Veterinary Research

Abstract

Objective—To quantify dimensions of the small intestine of dogs and describe changes in histologic characteristics of the mucosa during postnatal development.

Sample Population—Gastrointestinal tract tissues obtained from 110 Beagles (15 adult females and 95 puppies of both sexes).

Procedure—Several variables (length, total weight, mucosal weight, and nominal surface area) of the small intestine were measured in puppies at birth but before suckling; 1 day after birth and subsequent suckling, 21, 42, and 63 days after birth, and in the adult dams of the puppies. Tissue structure was examined and quantified at each time point by use of routine histologic examination and ocular micrometry of formalin-fixed specimens stained with H&E.

Results—Small intestinal dimensions increased throughout development with the greatest proportional changes during the first day after birth and onset of suckling. Villus height decreased during suckling but had consistent values from 42 days after birth to maturity, whereas crypt depth increased from birth to maturity. Vacuolated enterocytes were evident from birth to 21 days but not thereafter.

Conclusions and Clinical Relevance—Increases in intestinal dimensions provide growing dogs with a greater capacity for digestion and absorption. Changes in mucosal architecture and cell populations coincided with shifts in dietary inputs. These findings may assist in the diagnosis of small intestinal diseases and nutritional responses during growth and development of dogs. (Am J Vet Res 2003;64:618–626)

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in American Journal of Veterinary Research

Abstract

Objective—To examine the effects of various doses of mosapride, a 5-hydroxytryptamine 4 receptor agonist, on motility of the small intestine and cecum in horses by use of electrical activity and to determine the dose that provides the optimal response.

Animals—6 healthy adult Thoroughbreds.

Procedure—Electrical activity of the small intestine and cecum was recorded before and after mosapride administration by use of an electrogastrograph. Mosapride (0.5, 1, 1.5, and 2 mg/kg) was dissolved in 200 mL of water and administered orally to horses through a nasogastric tube. Three hours after drug administration, mean amplitude of electrical activity calculated for a period of 30 minutes was expressed as the percentage of the mean amplitude of electrical activity for a period of 30 minutes before drug administration.

Results—Mosapride administered orally increased the percentage of the mean amplitude of electrical activity in the small intestine and cecum in a dosedependent manner. Mean ± SD values differed significantly for 1, 1.5, and 2 mg/kg (127.0 ± 12.5%, 137.7 ± 22.2%, and 151.1 ± 24.0%, respectively) in the small intestine and for 1.5 and 2 mg/kg (130.1 ± 34.5% and 151.6 ± 45.2%, respectively) in the cecum.

Conclusions and Clinical Relevance—Analysis of results of this study clearly documents that mosapride promotes motility in the small intestine and cecum of horses and that the optimal orally administered dosage is 1.5 to 2 mg/kg. Therefore, mosapride may be useful for treatment of horses with gastrointestinal tract dysfunction. (Am J Vet Res 2005;66:1321–1323)

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in American Journal of Veterinary Research

SUMMARY

To examine the postnatal development of equine small intestine, biopsy specimens of jejunal mucosa from 8 ponies, between 6 and 28 weeks old, were subjected to analytical subcellular fractionation and assay organelle marker enzymes. Fractionation revealed a reduction in the particulate brush border component of β-galactosidase (lactase) activity between 6 and 28 weeks, and a corresponding increase in soluble activity, although the reduction in mean specific activity was not significant. There also was a decrease in the proportion of brush border to soluble aminopeptidase N activity, a relative loss of brush border γ-glutamyltransferase and a considerable decrease the specific activity of alkaline phosphatase throughout the gradient fractions. In contrast, there were marked increases in activities α-glucosidase (maltase) and sucrase in the older ponies, accompanied by considerable changes in the intracellular distribution of particulate α-glucosidase activity, which was predominantly associated with endoplasmic reticulum at 6 weeks, whereas the large increase in activity observed by 28 weeks was clearly associated with the brush border. The modal density brush borders also increased with age, suggestive of an increase in the glycoprotein-to-lipid ratio of the microvillar membrane. In contrast to these brush border changes, there was relatively little alteration in the activities or density distributions of marker enzymes for endoplasmic reticulum, basolateral membranes, mitochondria, or lysosomes. These findings indicate that maturation of equine intestinal epithelium during the first few months of life results in major changes in the properties and enzyme composition of enterocyte brush borders.

Free access
in American Journal of Veterinary Research

Summary

Effects of intraluminal distention (25 cm of H2O, 120 minutes) and subsequent decompression (60 minutes) on intramural vascular patterns of the small intestine was evaluated in 7 anesthetized horses. Intraluminal distention (25 cm of H2O, 120 mintutes) was created in 2 jejunal segments in each horse. Experimental and control segments were removed either immediately after the experimental period or after 60 minutes of decompression. The vascular system of experimental and control jejunal segments was lavaged with NaCl, then was injected with a blue-colored radiopaque medium for microangiography or with a diluted methyl methacrylate for scanning electron microscopy of microcorrosion vascular casts. After angiographic evaluation, tissue sections were prepared for light microscopic evaluation to assess vascular filling and tissue morphology. The distended segments had short villi, which were separated by expanded crypts, and had mesothelial cell loss, neutrophil infiltration, and edema in the seromuscular layer. The number of perfused vessels was significantly (P < 0.05) decreased in the seromuscular layer and, to a lesser extent, in the mucosal layer of the distended segments, compared with controls. After decompression, the morphologic lesions progressed in mucosal and serosal layers and the number of observed vessels increased in all intramural layers; however, vascular density did not return to the predistention state. These results identify altered intramural vascular patterns in the equine jejunum during luminal distention and subsequent decompression.

Free access
in American Journal of Veterinary Research