Veterinary Medicine - February 2008 - (Page MV3) experience, vestibular-induced causes and central nervous system disturbances that cause vomiting are infrequent. Many causes for acute vomiting are self-limiting and will not require speci c therapy. Dr. David Twedt: A lot of veterinarians associate vomiting with the gastrointestinal tract, but receptors also exist in the peritoneum, kidneys, urinary bladder, and thoracic cavity. Anything in those cavities could cause vomiting. Leib: With gastrointestinal visceral disease, the duodenum is extremely important. Sometimes the cause of the vomiting may be the duodenum or the rest of the small bowel—not the stomach. Dr. Kenneth Simpson: One of the more common causes of vomiting, apart from uremia, is the rapid administration of intravenous drugs. Leib: Does anyone think that with disorders such as gastritis, enteritis, or gallbladder disease, the vomiting center may receive input from both visceral a erent nerves and the chemoreceptor trigger zone? Jergens: I’ve performed gastrointestinal endoscopy in a handful of vomiting, uremic animals with gastric erosions or obvious mucosal abnormalities. When uremic toxins stimulate the chemoreceptor trigger zone with concurrent gastric mucosal disruption, both conditions may stimulate vomiting. The same is true for acute pancreatitis where mucosal in ammation and metabolic disturbances may contribute to vomiting episodes. Many common diseases have multiple modalities. Dr. David Williams: We often don’t know if the cause is a gastric, Figure 1. Causes of vomiting • Dietary indiscretion or intolerance (e.g., sudden diet change, foreign material ingestion, rapid ingestion, food intolerance or allergy, or hairballs) • Drug-related problems (e.g., intolerance, side effect, or overdose) • Toxins • Motion sickness • Metabolic or infectious disorders (e.g., diabetes mellitus, kidney disease, hypoadrenocorticism, liver disease, infectious canine hepatitis, or leptospirosis) • Disorders of the stomach, small intestine, and large intestine (e.g., acute gastritis, acute enteritis, parasitism, gastric/duodenal foreign body, parvovirus infection, coronavirus infection, intussusception, or hemorrhagic gastroenteritis) • Abdominal disorders (e.g., pancreatitis, peritonitis, liver disease, or gallbladder disease) pancreatic, or small intestinal modality. When patients have abnormalities in two or three locations, it’s sometimes hard to determine a single cause for the vomiting. Twedt: In ammatory bowel disease or Helicobacter gastritis cases are probably just peripheral in nature. But in animals with acute gastroenteritis, they ingest something, are a ected locally, and may absorb something that causes problems centrally. It’s hard to predict. defense mechanism for getting rid of rancid food or toxic substances once these substances stimulate the chemoreceptor trigger zone. Simpson: Often, the cases we have the most problems with are the ones involving, for example, a post-barbecue binge, where you try to discriminate acute gastroenteritis from acute pancreatitis. Leib: What about motion sickness? Williams: I think it is underdiagnosed in veterinary practice. Owners are far more aware of the problem than their veterinarians. Simpson: The mechanism would be vestibular input and is di erent in cats than dogs in terms of where it feeds into the vomiting pathway. I rarely deal with motion sickness. Leib: But it’s very common in general practice and has a profound impact on family automobile travel. Williams: While owners are aware of motion sickness in their pets, most don’t seek veterinary advice for its management. 3 Vomiting mechanisms Leib: Let’s look at Figure 1. What causes vomiting? Williams: I don’t think you usually know. It is often a local visceral response, but the animal may have ingested something that is absorbed and acts centrally. Leib: You’re referring to the potential for toxins to a ect the chemoreceptor trigger zone also. Twedt: I agree. Often we don’t know whether it’s foreign material causing gastric irritation or absorption of toxic substances. In evolutionary terms, vomiting is the
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