borborygmus and FLATULENCE
Borborygmus is a term used to describe a rumbling type of gut sound. Borborygmi are due to a moving gas-fluid interface in the gut. These sounds usually originate in the stomach.
Borborygmi most commonly affect the dog. They are rarely heard emanating from cats. Borborygmus and flatulence commonly result from dietary indiscretion; however, these signs may be exaggerated in malassimilation or in any condition that promotes bacterial fermentation of malabsorbed carbohydrates and proteins. They may also occur as a matter of course in some normal patients or in association with functional bowel disorders (e.g., irritable bowel syndrome). Owners of patients that display these symptoms, especially flatulence, invariably highlight information about their occurrence as they discuss their pet's history. Indeed, sometimes offensive flatulence is the primary reason for seeking veterinary consultation.Gas is normally present in the GI tract. The two most common sources of intestinal gas in humans and animals are swallowed air and bacterial fermentation. In adult humans the volume of intraluminal intestinal gas present at any one time varies from 140 to 260 ml. No such figures are available for animals. Most (99%) of the gas present in the GI tract is composed of five gases: nitrogen, oxygen, carbon dioxide, hydrogen, and methane. All of these gases are odorless. The unpleasant odor that may be detected in flatus is probably imparted by other gases that are present in trace amounts and by hydrogen sulfide and mercaptans metabolized from sulfur-containing substances present in certain foods.
The upper GI tract contains oxygen, nitrogen, and carbon dioxide, whereas the colon contains hydrogen, methane, and carbon dioxide. The source of oxygen and nitrogen is inspired air. Carbon dioxide is produced by the interaction of acid and alkaline substances in the stomach.
Much of the carbon dioxide generated is absorbed through the bloodstream. Gas generated in the lower intestinal tract is the result of bacterial fermentation. Fermentation by the colon flora results in the production of variable amounts of hydrogen, methane, carbon dioxide, and oxygen.The GI transit time for gas is considerably shorter than for liquids or solids. Gas introduced to the stomach of humans can be passed in as little time as 15 minutes. Overdistention of the GI tract with gas can potentially lead to significant discomfort. Patients will frequently continue to shift positions or assume an arched stance when experiencing gas-related discomfort.
Historical Features
The complaints described by owners of dogs with “gaseousness” problems include the pet's (1) tendency to bloat, with or without belching, (2) assumption of an arched back stance, which might indicate cramping, and (3) excessive expulsion of flatus. Generally these symptoms occur only individually in a patient. It is rare for any single patient to exhibit all three of these main symptoms.
These symptoms should not be treated cavalierly or be dismissed too rapidly as insignificant by the clinician. Although in some patients the problem may simply be related to aerophagia, as may be caused by excitement, eating too rapidly, or eating foods that are high “gas producers,” in other patients a more serious disorder may be present. For example, some dogs with gastric hypomotility disease or gastric outflow obstruction tend to experience bloating or a feeling of abdominal distention. Many of these dogs exhibit intermittent to frequent signs of nausea, and vomiting frequently occurs. Pronounced borborygmi may be present. There may be intermittent inappetence as well. Early in the course of the disorder there may be minimal symptoms, but as the disorder progresses, there may be significant patient discomfort. This is also true of the patient with inflammatory bowel disease or irritable bowel syndrome that tends to stand at times with an arched back because of abdominal discomfort related to gas pain. Diagnostic efforts should be undertaken to determine the cause of the symptoms in these patients.
Treatment often provides significant relief. Although patients with excessive flatus do not often exhibit signs of discomfort, they may be affected by a malassimilation disorder that warrants diagnostic efforts.Diagnosis
Diagnosis involves a review of historical factors, physical examination, and selected tests based on the primary symptoms and the degree of significance that the clinician affords them. The evaluation of a patient with flatulence includes determination of the daily diet and whether there exist opportunities for dietary indiscretion. Legumes, such as soybean meal, and vegetables such as beans, cabbage, lentils, and brussel sprouts are known as “gas producers.” Legumes contain large quantities of oligosaccharides that are indigestible because the normal gut lacks the enzymes necessary to metabolize them. Ten percent to 20% of ingested carbohydrates may be malabsorbed, and protein substrates, when fermented, may contribute to gaseous constituents. Spoiled foods are likely to yield increased quantities of odiferous gases. Milk products may cause gaseousness in patients with lactase deficiency. The owner should also be questioned about the patient's eating habits. Excessive aerophagia may occur when liquid or solid food is bolted or eaten rapidly. For some patients this may simply be habit, whereas in others it may result from a sense of competition with other animals in the immediate vicinity for rights to the food. Patients that are quite active (e.g., working dogs) may have a tendency to be aerophagic and produce excessive flatus as a result.
When the flatulence is fairly recent in occurrence and is accompanied by other signs, such as inappetence, weight loss, evidence of abdominal discomfort, and diarrhea, a detailed work-up is in order. Depending on the patient's environment and the dominant symptoms, this may include fecal analysis for evidence of Giardi (both zinc sulfate centrifugal flotation and a Giardia antigen test), TLI assay to investigate for EPI, cobalamin and folate assays for intestinal bacterial overgrowth, survey and possibly contrast radiographs of the GI tract (with particular attention paid to transit time, as well as to any morphologic abnormalities), and endoscopy to obtain gastric and intestinal biopsy samples (rule out infiltrative disorders).
Treatment often involves dietary manipulation (with change to foods that are highly digestible and low in fiber, with a moderate protein content and a novel protein source), feeding smaller meals more frequently if too rapid ingestion of food is considered a problem, and treatment of any primary disorder that might be identified by the tests listed above. Occasionally, gas-reducing drugs are used. Pharmacologic management attempts may include adsorbents, antifoaming agents, or various enzyme preparations. Response to these products is often variable. Charcoal is an absorbent that has been commonly used in humans. Simethicone is an antifoaming agent that reduces surface tension and promotes coalescence of bubbles so that they can be more easily passed. Simethicone is not absorbed from the GI tract and can be used safely in dogs and cats, although its effectiveness is unknown.
An antiflatulence treat preparation was studied and shown to be beneficial for reduction of the offensive odor of flatulence in dogs. The treats included activated charcoal, Yucca schidigera, and zinc acetate. Treated dogs experienced a significant reduction in the percentage of highly odoriferous episodes. In vivo hydrogen sulfide levels were significantly reduced. Treatment for excessive flatus is discussed in more detail in Chapter 7.