Intragastric pH in critically ill neonatal foals and the effect of ranitidine

Objective-To characterize intragastric pH profiles in critically ill foals and determine whether administration of ranitidine altered pH profiles. Design-Prospective observational study. Animals-23 hospitalized neonatal foals less than or equal to 4 days of age. Procedure-Intragastric pH was measured continuously for up to 24 hours by u se of an indwelling electrode and continuous data recording system. In 21 f oals, ranitidine was administered IV. Results-10 foals had predominantly or exclusively alkaline profiles, 10 had profiles typical of those reported for healthy foals, with periods of acid ity (hourly mean pH < 5.0 at least once), and 3 had atypical profiles with periods of acidity. All 10 feats that had intragastric pH profiles typical of healthy foals survived, whereas only 2 foals with alkaline profiles surv ived, and none of the foals with atypical profiles survived. The effects of ranitidine administration could not be assessed in 13 foals because of a h igh baseline intragastric pH. in 7 of the remaining 9, ranitidine administr ation resulted in an alkalinizing response, but this response was often of blunted duration. Ranitidine administration did not appear to alter the int ragastric pH profile in the remaining 2 foals. Conclusions and Clinical Relevance-Results suggested that hospitalized crit ically iii foals often have intragastric pH profiles different from those r eported for healthy foals and may respond differently to ranitidine adminis tration than do healthy foals. Many critically ill foals have continuously alkaline intragastric pH profiles, questioning the need for prophylactic ad ministration of ranitidine in all critically ill foals.