Intragastric feeding in the neonatal dog. Its effect on intestinal osmolality.

Hypertonic formulas have been implicated in the etiology of necrotizing enterocolitis. We measured the osmolality of neonatal canine intestinal contents one hour after intragastric feeding of isotonic breast milk, isotonic formula, or hypertonic formula in 1-day-old and 9-day-old puppies. Regardless of the formula tonicity, all intestinal contents were hypertonic in both segments. Hypertonic formula had been diluted, and isotonic feedings concentrated in the neonatal canine intestine. Gastric contents could be recovered only from hypertonic-fed puppies, which implies delayed gastric emptying to permit formula dilution. We conclude that any form of neonatal feeding can lead to hypertonic intestinal contents. Factors other than tonicity of a formula should be considered in the pathophysiology of necrotizing enterocolitis.