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Summary

Accumulation of d-xylose by jejunal mucosa from healthy horses and rabbits was studied in vitro. When tissue sheets were incubated with 1 mM d-xylose for 60 minutes, mucosa from horses and rabbits accumulated d-xylose against a concentration gradient. There was no accumulation when equine specimens were incubated with 5 mM d-xylose. By comparison, equine jejunum accumulated d-glucose against a concentration gradient when incubated in 5 mM D-glucose. In equine and rabbit jejunum, 13.3 ± 7.0% and 36 ± 11.0%, respectively, of accumulated Dxylose was phosphorylated when sheets were incubated in 1 mM d-xylose. Short-circuit current and potential difference were lower in equine jejunum than in rabbit jejunum, possibly because of differences in tissue thickness. None of the transmucosal electrical measurements increased after addition of d-xylose (1 mM and 5 mM) or d-glucose (5 mM).

The active transport system for d-xylose has a low affinity for this sugar and becomes saturated at low intraluminal concentrations. Therefore, abnormal d-xylose absorption test results in horses are more likely caused by abnormalities in mucosal surface area and mucosal permeability than by abnormalities of nutrient carbohydrate absorption.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To test the hypothesis that strangulation of the small intestine by a lipoma or in the epiploic foramen is more common in older horses.

Design—Retrospective study.

Animals—46 horses.

Procedure—Ages of horses with strangulation of the small intestine by a lipoma (n = 29) or in the epiploic foramen (17) were compared with ages of 79 horses with miscellaneous small intestinal lesions. Effects of increasing age on risk of the diseases of interest were examined by use of logistic regression and a 1-sided trend test for binomial proportions.

Results—Mean age of the horses with strangulation in the epiploic foramen (9.6 years) was the same as that for the horses with miscellaneous small intestinal lesions (7.7), but mean age of the horses with strangulation by a lipoma (19.2) was significantly greater than that for the other groups. The proportion of horses with lipoma increased significantly with increasing age, but the proportion with strangulation in the epiploic foramen did not.

Conclusions and Clinical Relevance—Results refute the current suggestion that increasing age predisposes horses for strangulation of the small intestine in the epiploic foramen but support the suggestion that the risk of strangulation of the small intestine by a lipoma increases with age. (J Am Vet Med Assoc 2001;219:87–89)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate survival rate and complications after jejunocecostomy in horses with colic and to compare outcomes after hand-sewn versus stapled side-to-side jejunocecostomy.

Design—Retrospective cohort study. Animals—32 horses.

Procedures—Information was retrieved from medical records and through telephone calls on horses that had a hand-sewn or stapled side-to-side jejunocecostomy for treatment of colic, which was performed by or under the supervision of the same surgeon. KaplanMeier life table analysis was used to compare survival times and rates between horses that underwent a hand-sewn or stapled side-to-side anastomosis.

Results—32 horses met inclusion criteria; 22 underwent a hand-sewn anastomosis, and 10 underwent a stapled anastomosis. Horses in the stapled group had a significantly greater prevalence of postoperative colic and combined postoperative colic and reflux than horses in the hand-sewn group. In the hand-sewn group, repeated celiotomy was performed within the same hospitalization period for 3 of 22 horses; in the stapled group, 4 of 10 horses had repeated celiotomies. Hospital discharge rates (ie, short-term survival rates) were similar between horses in the hand-sewn group (20/22 horses) and those in the stapled group (9/10 horses). Long-term survival rates were similar for both groups, ranging from 5 to 126 months. Conclusions and Clinical Relevance—Short- and long-term results justify use of jejunocecostomy in horses. Despite similar survival rates between groups, horses that underwent a stapled anastomosis had significantly greater prevalences of postoperative complications than horses that underwent a hand-sewn anastomosis, suggesting that horses were sensitive to minor differences in anastomosis techniques.

Full access
in Journal of the American Veterinary Medical Association

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.

Free access
in American Journal of Veterinary Research

SUMMARY

Mucosa obtained from the cecum of healthy horses and incubated in vitro with 0.1 mM cycloleucine could accumulate this amino acid against an apparent concentration gradient after 60 and 120 minutes. Accumulation by the serosal (antiluminal) surface of the tissue was 3 times greater than accumulation by the mucosal (luminal) surface after 120 minutes (P < 0.001). Cycloleucine accumulation was significantly reduced by Na deprivation after 60 minutes (P< 0.05) and 120 minutes (P < 0.01) and by anoxic conditions after 120 minutes (P < 0.05). Transmucosal flux from mucosal to serosal surface of the tissue was significantly (P < 0.05) greater than the opposing flux, but both unidirectional fluxes were small and were largely attributed to passive processes. It was concluded that the most avid transport system for cycloleucine was on the serosal surface of the horse's cecal mucosa, and an active transport system was not evident on the mucosal surface. An active transport system for amino acids on the serosal surface could be explained by the need for crypt cells, the predominant epithelial cell type in the cecum, to obtain nutrients from blood, rather than from the intestinal lumen.

Free access
in American Journal of Veterinary Research

SUMMARY

Age, breed, and gender distributions of 168 horses with umbilical hernia treated at the University of Pennsylvania School of Veterinary Medicine were analyzed to determine risk factors for this disease. For the 3 breeds that constituted the largest proportion of hospital and case populations, Thoroughbred, Standardbred, and Quarter Horse, the overall ratio of females to males was 1.63. In a hospital population of the same age group, 0 to 48 months, the female to male ratio was 0.93. Compared with males, females were at significantly higher risk for umbilical hernia after adjustment for breed and age (odds ratio, 2.01; 99% confidence interval, 1.31 to 3.10; P = 0.00002). Of the 2 major breeds, Thoroughbreds were at greater risk than Standardbreds for umbilical hernia, after adjustment for gender and age (odds ratio, 1.80; 99% confidence interval, 1.10 to 2.95; P = 0.0020). The results provide information about a common congenital defect in horses that can be used for future genetic research.

Free access
in American Journal of Veterinary Research

SUMMARY

Objectives

To study effects of hypochlorous acid (HOCI) on equine colonic mucosa in vitro, and determine whether addition of ascorbic acid protects against the effects.

Animals

6 healthy horses and ponies.

Procedure

Short-circuit current was measured in mucosa mounted in Ussing chambers. Incubation conditions were: control (no additions); 5 mM HOCI; 1 mM HOCI; same and 5 mM ascorbic acid; 3 mM HOCI; 3 mM HOCI and 5 mM ascorbic acid; 7 mM HOCI; and 7 mM HOCI plus 5 mM ascorbic acid. Permeability was measured with [3H]mannitol and, at the conclusion of each experiment, tissues were examined microscopically to assess the effects of HOCI and ascorbic acid, alone or in combination.

Results

Short circuit current and conductance increased transiently in response to 1 mM HOCI. Tissues had mild surface epithelial damage, as evident by swelling and separation of isolated cells. These changes were abolished when tissues were coincubated with 5 mM ascorbic acid and 1 mM HOCI. At 3 and 7 mM concentrations, HOCI caused marked increase in tissue conductance, short circuit current, and permeability to mannitol; these changes were associated with histologic damage. Again, coincubation with 5 mM ascorbic acid protected against these changes. Additional studies indicated that the effects of HOCI and the protective effects of ascorbic acid were not mediated through changes in pH.

Conclusions

HOCI in low concentrations is capable of increasing the short-circuit current in equine colon, possibly by increasing secretions; however, higher concentrations can cause tissue damage. The addition of 5 mM ascorbic acid blocks these changes.

Clinical Relevance

The concentration of HOCI produced by activated neutrophils could damage equine colonic mucosa and potentially contribute to or cause reperfusion injury. The ability of ascorbic acid to ameliorate this injury in an in vitro setting offers a potential method for pharmacologic evaluation of this injury and for treatment. (Am J Vet Res 1998;59:82–87)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine the rate of development of septic arthritis after elective arthroscopy and evaluate associations between various factors and development of this complication in horses.

Design—Retrospective case series.

Animals—682 horses that underwent arthroscopic procedures at the University of Illinois Veterinary Teaching Hospital from 1994 to 2003.

Procedures—Information pertaining to signalment, joints treated, whether antimicrobials were administered, and development of postoperative septic arthritis was collected from medical records. Horses with a primary problem of septic arthritis or wounds involving joints were excluded. The following factors were evaluated to determine their roles in joint sepsis: breed, sex, joint, and preoperative and intra-articular administration of antimicrobials. Telephone interviews with clients were used to determine whether unreported septic arthritis had developed.

Results—8 of 932 (0.9%) joints in 7 of 682 (1.0%) horses that underwent arthroscopy developed postoperative septic arthritis. Follow-up information after discharge from the hospital was available for 461 of the 682 horses, and of those, 8 of 627 (1.3%) joints in 7 of 461 (1.5%) horses developed septic arthritis. Breed and joint treated were significant risk factors for development of postoperative septic arthritis, with draft breeds and tibiotarsal joints more likely than others to be affected. Sex, preoperatively administered antimicrobials, and intra-articularly administered antimicrobials were not associated with development of postoperative septic arthritis.

Conclusions and Clinical Relevance—Results can be used for comparison with data from other institutions and surgical facilities. Additional precautions should be undertaken when arthroscopic surgery involves draft breeds and tibiotarsal joints.

Full access
in Journal of the American Veterinary Medical Association

Summary

Multicompartmental analysis was applied to study the kinetics of D-xylose distribution after its intragastric administration to healthy mares deprived of food for 12, 36, 72, and 96 hours. Disposition of D-xylose was described by a 5-compartment model. Maximal plasma D-xylose concentration was similar for 12 and 36 hours of food deprivation and was greater (P = 0.0001) than the values for 72 and 96 hours. Peak concentration of D-xylose appeared progressively later as food deprivation proceeded (P = 0.0001). Fractional rate of transfer (k1,6) was less after 96 hours of food deprivation, compared with 12 hours (P = 0.0001), and percentage of D-xylose absorbed was reduced (P = 0.0441) after food deprivation. Fractional rate of transfer (k6,5), representing gastric emptying, tended to progressively decrease with food deprivation.

Results indicated that formal kinetic analysis can be applied to D-xylose absorption kinetics in horses. Reduction in the extent of D-xylose absorption after food deprivation may be partly caused by decreased rate of D-xylose absorption across the small intestinal mucosa, but other factors, such as gastric emptying and nonabsorptive losses, may also be involved.

Free access
in American Journal of Veterinary Research

SUMMARY

Multicompartmental analysis was applied to study the kinetics of D-xylose distribution after IV administration to healthy mares deprived of food for 12 and 96 hours. Urinary excretion of D-xylose was measured over a 15-hour period after administration. The plasma D-xylose concentrations in this study were in the range found after oral tolerance testing. The disposition of D-xylose was described by a two-compartment model with linear kinetic characteristics. Total volume of distribution decreased significantly (P < 0.025) from 0.270 L/kg of body weight after the 12-hour period of food deprivation to 0.235 L/kg after the 96-hour period. Fractional rate of transfer between the central and peripheral compartments did not change after 96 hours without food. Approximately a third of the D-xylose administered was recovered in the urine. Difference in urinary elimination between the 12- and 96-hour periods was not significant. Nonrenal elimination rate was determined to be twice the renal elimination rate.

The results indicated that formal kinetic analysis can provide useful information about D-xylose distribution in horses. The decreased D-xylose space found after a 96-hour period of food deprivation would tend to increase the plasma D-xylose concentration, and this may help in the interpretation of the D-xylose absorption test applied to anorectic horses.

Free access
in American Journal of Veterinary Research