Effect of a fixed pyloric opening on gastric emptying in the cat and dog

The effect of preventing pyloric closure on the rate of gastric emptying without alteration of the gastroduodenal junction was studied in six dogs and four cats with gastric fistulas. Each had a Teflon cannula with an internal diameter of 1.0 or 1.25 cm (dog) and 0.6 cm (cat) sewn into the pyloric channel. At the completion of the initial series of tests, the cannulas were removed and the studies repeated. Test meals were 240 and 480 ml of water, acid (120 mM HC1), and hyperosmotic glucose (555 mM) in the dogs and 50 ml of water, acid (100 mM HC1) and fat (20 mM Na oleate) in the cats. Phenol red was used as a nonabsorbable marker. The residual volumes were collected at 15-40 min in the dogs and 15-20 min in the cats. In both species, the rate of emptying of all the meals was unaffected by the pyloric cannula. In the dog, added secretions were greater with the pyloric cannula in place, suggesting reflux of duodenal contents. This study indicates that while the pylorus is unimportant in the gastric emptying of liquids in the dog and cat, it may have a role in prevention of duodenal reflux.