EFFECT OF ALUMINUM HYDROXIDE MAGNESIUM-HYDROXIDE ANTACID AND BISMUTH SUBSALICYLATE ON GASTRIC PH IN HORSES

Objective-To assess the effect of aluminum hydroxide/magnesium hydroxi de antacid and bismuth subsalicylate on gastric pH in clinically norma l horses and to develop guidelines on the use of these agents for trea tment of peptic ulcer disease in horses. Design-Prospective, randomize d, controlled trial. Animals-5 clinically normal adult horses with chr onically implanted gastric cannulas. Procedure-Each horse received all 5 treatments (30 g of aluminum hydroxide/15 g of magnesium hydroxide, 12 g of aluminum hydroxide/6 g of magnesium hydroxide, 10.5 g of bism uth subsalicylate, 26.25 g of bismuth subsalicylate, and 5% methylcell ulose control) with only 1 experiment performed each day. Gastric pH w as measured via a glass electrode inserted through the gastric cannula for 1 hour before treatment and continued for 2 hours after treatment . Food or water was not given to the horses during the experiment. Mea surements of gastric pH obtained during posttreatment hours were compa red with pretreatment gastric pH values. Results-Only a dose of 30 g o f aluminum hydroxide/15 g of magnesium hydroxide resulted in a signifi cant increase in gastric pH over baseline or control values. Mean pH w as 5.2 +/- 0.62 and 4.59 +/- 0.48 for posttreatment hours 1 and 2, res pectively. Clinical Implications-Oral administration of 30 g of alumin um hydroxide/15 g of magnesium hydroxide to adult horses should result in a mean hourly gastric pH greater than or equal to 4.0 for al least 2 hours.