Ulceration of the pars oesophagea is a cause of sow and grow-finish mortality. The mortality rate due to gastric ulceration has increased in the past decade and is one of the most important causes of death. Many hogs at slaughter have some degree of ulceration. It is difficult to address the severity of the ulceration by inspection alone. Unless ulcerations are severe and chronic, there seems to be no relationship between growth rate and stomach lesions. If feed particle size is too small it will increase the incidence of death by ulceration, but the feed-to-gain efficiency improves. Anything less than 700 to 750 microns is the point where ulceration begins. Small feed particles pass through faster and increase the fluidity of the stomach, which allows more contact of stomach acids with the stomach wall lining. The most practical solution is to ensure there is no disruption in the feeding program. Respiratory disease in a grow-finish barn is recognized as resulting in an increase in ulcers. Alkaline salts have been investigated as practical feed additives to help neutralize acidity in the stomach and improve structure of the gut. Surprisingly, gastric ulcers are highly heritable. There is some belief that ulcers are infectious. Many pigs that had ulcers housed certain bacteria that are thought to lead to ulceration.