Flatulence: Causes and Management Options

Flatulence is defined as excessive formation of gases in the stomach or intestine. It is usually associated with noticeable flatus, belching, borborygmus, abdominal distention, or a combination of these signs. Excessive aerophagia is a risk factor for flatulence and is noted commonly in brachycephalic, working, and sporting breeds as well as in dogs with aggressive or competitive eating behaviors. The primary goal of dietary management of flatulence is to reduce the gas formation that results from bacterial fermentation of intestinal substrates. Flatulence—excessive formation of gases in the stomach or intestine—is usually associated with noticeable flatus, belching, borborygmus, abdominal distention, or a combination of these signs. Flatus, rather than flatulence, is the term that should be used for gas expelled through the anus. Belching is the noisy voiding of gas from the stomach through the mouth, and borborygmus is a rumbling or gurgling noise caused by propulsion of gas through the intestines. Excessive flatus is a chronic, objectionable problem that is common in dogs but less so in cats. Although belching, borborygmus, and abdominal distention are less common signs, pet owners may mention them if asked specifically about them. Flatus, belching, and borborygmus occur in healthy pets but may also develop as a consequence of gastric, small intestinal, or colonic disorders. PRODUCTION OF INTESTINAL GAS The tendency to treat flatus as a humorous topic has obscured appreciation of the complex physiology that underlies the formation of intestinal gas. The quantitatively important gases in the intestinal tract are nitrogen (N2), oxygen (O2), hydrogen (H2), carbon dioxide (CO2), and methane (CH4). These odorless gases make up more than 99% of the intestinal gas volume in humans and pets (Table 1). The characteristic unpleasant odor of intestinal gas arises primarily from the trace gases that contain volatile sulfur compounds such as hydrogen sulfide, methanethiol, and dimethylsulfide. The noxious odor of flatus in both humans and dogs correlates most strongly with the concentration of hydrogen sulfide. Gas occurs naturally in the gastrointestinal (GI) tract and primarily results from the following four events: CE Vol. 23, No. 12 December 2001 1075 V n More than 99% of intestinal gas is comprised of odorless gases, including nitrogen, oxygen, hydrogen, carbon dioxide, and