Alfred M. Merritt

Effect of Dietary Corn Oil Supplementation on Equine Gastric Fluid Acid, Sodium, and Prostaglandin E2 Content before and during Pentagastrin Infusion

The effect of corn oil (approximately 60% [wt/vol] linoleic acid) dietary supplementation on various components of equine gastric secretion was studied by use of a repeated-measures experimental design. Four healthy adult ponies were surgically fitted with gastric cannulas. The ponies were then fed a free-choice hay diet for 5 weeks, which was followed by 5 weeks of the same diet supplemented with 45 mL of corn oil daily. Gastric contents were analyzed under basal and pentagastrin-stimulated conditions once weekly during the latter 2 weeks on each diet. Gastric contents were collected at 30-minute intervals, and volume, hydrogen ion concentration, sodium content, and prostaglandin E2 (PGE2) content were measured. Data were analyzed by a linear fixed-effect modeling procedure. During the diet supplemented with corn oil, the ponies had, under basal and pentagastrin-stimulated conditions, significantly decreased acid output and significantly increased PGE2 and sodium outputs compared to those measured before corn oil supplementation. We conclude that corn oil supplementation may be an effective and inexpensive way to increase the protective properties of equine glandular gastric mucosa. This could be particularly helpful in reducing the chances of ulceration associated with nonsteroidal anti-inflammatory drug (NSAID) administration.

Systemic, renal, and colonic effects of intravenous and enteral rehydration in horses

BACKGROUND Intravenous (IV) and intragastric (IG) administration of fluid therapy are commonly used in equine practice, but there are limited data on the systemic, renal, and enteric effects. HYPOTHESIS IV fluid administration will increase intestinal and fecal hydration in a rate-dependent manner after hypertonic dehydration, but will be associated with significant urinary water and electrolyte loss. Equivalent volumes of IG plain water will result in comparatively greater intestinal hydration with less renal loss. ANIMALS Six Thoroughbred geldings. METHODS Experimental study. 6 by 6 Latin square design investigating constant rate IV administration at 50, 100, and 150 mL/kg/d over 24 hours in horses dehydrated by water deprivation. Equivalent volumes of IG plain water were administered by 4 bolus doses over 24 hours. RESULTS Water deprivation resulted in a significant decrease in the percentage of fecal water, and increases in serum and urine osmolality. IV fluids administered at 100 and 150 mL/kg/d restored fecal hydration, but increasing the rate from 100 to 150 mL/kg/d did not confer any additional intestinal benefit, but did result in significantly greater urine production and sodium loss. Equivalent 24-hour volumes of plain water resulted in greater intestinal water and less urine output. CONCLUSIONS AND CLINICAL IMPORTANCE IV polyionic isotonic fluids can be used to hydrate intestinal contents in situations where enteral fluids are impractical. IV fluids administered at three times maintenance are no more efficacious and might be associated with adverse physiological findings after withdrawal. Bolus dosing of IG water can be used to restore intestinal water with minimal adverse effects.