Small intestinal malabsorption in horses

A retrospective study of horses investigated for weight loss despite a good appetite (2002-2011)

REASONS FOR PERFORMING STUDY

Weight loss despite a good appetite is a frequent diagnostic challenge for equine veterinarians; however, there are few objective reports and little descriptive information regarding risk factors and prognostic indicators.

OBJECTIVES

To provide a descriptive epidemiological analysis of horses evaluated for weight loss despite a good appetite and evaluate relationships between historical and clinicopathological findings and final outcome (survival vs. nonsurvival) to identify risk factors and prognostic indicators.

METHODS

Medical records of horses referred for investigation of weight loss despite a good appetite were reviewed. Data collated included history, case details, clinical and diagnostic findings, diagnoses and outcome. Univariable associations were evaluated with a Mann-Whitney U test (continuous data), Fisher's exact test (categorical or binary data) or Pearson's rank correlation (continuous data), with P≤0.05 significant.

RESULTS

Forty cases met the inclusion criteria. Total protein (P = 0.004) and albumin concentrations (P = 0.0008) at admission were higher in survivors than nonsurvivors, with total protein (r(2) = 0.31; P = 0.002) and albumin (r(2) = 0.36; P = 0.0002) positively correlated with outcome. Hypoproteinaemic (P = 0.008, odds ratio (OR) = 12, 95% confidence interval (CI) = 1.99-72.4) and hypoalbuminaemic (P = 0.0009, OR = 28, 95% CI = 2.94-266.6) animals were at greater odds for nonsurvival. Body condition score was positively correlated with total protein (r(2) = 0.16; P = 0.05) and albumin (r(2) = 0.53; P<0.0001) concentrations at admission and duration of clinical signs (r(2) = 0.19; P = 0.03).

CONCLUSIONS

The severity of hypoproteinaemia and hypoalbuminaemia were related with nonsurvival. Body condition score and albumin concentration could potentially be used as prognostic indicators for survival.

POTENTIAL RELEVANCE

These findings highlight the importance of body condition assessment in conjunction with clinicopathological evaluation in horses with weight loss despite a good appetite.

The effect of sedation on D(+)-xylose absorption tests in 6 normal horses

REASONS FOR PERFORMING STUDY

D(+)-xylose absorption tests are commonly performed when investigating suspected small intestinal malabsorption in the horse. The test involves the administration of a D(+)-xylose solution via a nasogastric tube followed by serial blood sampling to determine its rate of absorption. In some horses, nasogastric intubation cannot be safely performed without prior administration of a sedative. Due to its short duration of action, the α(2) agonist xylazine is commonly used for this purpose. However, α(2) agonists have also been reported to influence the rate of gastric emptying as well as small intestinal motility patterns.

OBJECTIVE

To evaluate if prior sedation with xylazine would influence the rate of absorption of D(+)-xylose in 6 normal Standardbred horses in a randomised cross-over study.

METHODS

D(+)-xylose was administered by nasogastric intubation at a dose rate of 0.5 g/kg bwt given as a 10% solution with water while xylazine was administered iv at a dose rate of 0.5 mg/kg bwt. A heparinised blood sample was collected prior to administration of D(+)-xylose (and xylazine when used) and then at 30, 45, 60, 75, 90, 120, 150, 180 and 240 min following administration. Samples were immediately analysed using a modified colorimetric micro method. The cumulative amount of D(+)-xylose absorbed at each time point with and without prior sedation were. The significance rate was set at P<0.05.

RESULTS

The study failed to demonstrate a statistically significant difference in the amount of D(+)-xylose absorbed between sedated and unsedated animals, although there was a tendency for a less rapid initial uptake with prior sedation.

CONCLUSION

This study suggests that prior sedation with xylazine will not significantly affect the result of a D(+)-xylose absorption test in the normal horse.

Obstruction of equine small intestine associated with focal idiopathic eosinophilic enteritis: An emerging disease?

Idiopathic focal eosinophilic enteritis (IFEE) is a rare disease in the horse and few cases have been reported in the literature. The objective of this paper was to describe the clinical, surgical, histological features and post-operative progress of 12 horses with IFEE, a disease that had not been identified in the authors' hospital population prior to 2000. Diagnosis of IFEE was made at laparotomy and confirmed by histological examination of resected abnormal small intestine. In all 12 horses colic was associated with jejunal obstruction involving visibly striking and palpably thickened serosal plaques or circumferential constrictions. Surgical resection of affected intestine was performed in 10 horses, of which seven completely recovered. In one horse, on which surgical resection was not performed, ingesta re-obstructed post-operatively at one of the lesions. Histological examination of resected intestines revealed, in all cases, severe transmural enteritis in which eosinophilic leucocytes were the predominant inflammatory cells. No helminths were identified and the cause of this lesion is not known. IFEE is an uncommon but significant cause of small intestinal obstruction for which surgical resection can be curative. The gross lesions may be under-recognised and histology is essential for diagnosis.