Diagnostic approach to vomiting (Proceedings)

Apr 01, 2010

Vomiting is among the most common clinical signs in companion animals. Although a protective mechanism associated with removal of noxious ingested substances, it is also associated with many diseases. Due to the multitude of causes it can be a challenge for veterinarians to diagnose and manage vomiting. Vomiting is not a diagnosis but is a clinical sign of any number of disorders including gastrointestinal disorders, systemic or metabolic disorders and toxicities. Sudden onset vomiting or chronic, intermittent vomiting causes significant concern for pet owners. Left untreated, vomiting can cause serious complications such as volume depletion, acid-base disturbances, esophagitis, and malnutrition or malabsorption and/or aspiration pneumonia.

Although the presentation of vomiting may not signify a serious disorder – it is often the first clinical sign in toxin ingestion, pancreatitis, renal failure, Addisonian crisis, parvovirus infection, and intestinal obstruction. A thorough evaluation must be performed to arrive at an accurate, timely diagnosis. It is also of paramount importance that the clinician questions the owner about potential toxin ingestion (ethylene glycol, medication ingestion, chocolate or xylitol) or other pertinent history.

It is essential to differentiate between vomiting and regurgitation at the outset. Regurgitation is defined as passive, retrograde movement of ingested material. It usually happens right after ingestion before the ingesta reaches the stomach, although it can be delayed hours. Vomiting is defined as a forceful rejection of gastric and sometimes proximal small intestinal contents via the oral cavity. Vomiting involves three stages: nausea (depression, salivation, lip-licking frequent swallowing and sometimes vocalization), retching, and expulsion. The history can be helpful to confirm the patient is vomiting and the signs are not associated with coughing, gagging, dysphagia or regurgitation, which are very confusing to the owner. In some cases the distinction is difficult to differentiate based on history alone.

Once you have determined vomiting is present, a complete historical review with emphasis on all body systems is imperative to develop an effective diagnostic plan. For example patient signalment may indicate a young, unvaccinated animal that is more susceptible to infectious disease, such as distemper or parvovirus. Consider the following 1) duration of signs, 2) frequency of signs (acute? chronic? intermittent?), 3) appearance of the vomit (projectile?), 4) association with drinking or eating, 5) signalment and past pertinent history and treatments, 6) diet and environment, 7) review of systems, (PU/PD? coughing? sneezing? diarrhea?), 8) content of the vomitus (food? bile? blood?).

A thorough dietary history, including type of diet, recent diet change, feeding of table scraps, free-roaming behavior allowing ingestion of garbage or foreign objects or toxins (including house plants or nsaids) is very important. Vomiting in the immediate post-prandial period may suggest an adverse reaction or intolerance to food or simply over eating. Vomiting a partially digested or undigested meal after six to eight hours of eating indicates a gastric outflow obstruction (caused by foreign bodies, polyps, mucosal hypertrophy and or tumors.). Vomiting bile-tinged fluid in the morning often results from bilious vomiting syndrome or reflux gastritis. Bright red blood or digested blood in the vomitus indicates gastrointestinal erosion or ulcer. The history may identify the use of medications, such as nsaids, which can cause gastritis or ulceration. The presence of additional concurrent signs, such as diarrhea, may help to order the rule-out list.

A complete physical exam can be normal or demonstrate other symptoms and therefore provide additional information. If vomiting is more constant, signs of dehydration may be present including delayed capillary refill time, decreased skin turgor, enophthalmos, pale mucous membranes, tachycardia and cold extremities. The abdomen should be carefully palpated to check for masses, foreign bodies, dilated loops of bowel, intussusceptions, effusion or organomegaly. A rectal examination provides characteristics of colonic mucosa and feces character. Patients with colitis or severe constipation often vomit. Foreign material in the feces infers foreign body ingestion. Melena is suggestive of bleeding in the upper gastrointestinal tract. Polyuria, polydipsia, polyphagia, pale mucus membranes, bradycardia or tachycardia, hepatomegaly or splenomegaly, small irregular kidneys, ascites, and icterus are all signs suggestive of systemic disease.

The history and physical examination findings should guide the clinician to the next step in the work-up if a diagnosis is not found. Because most cases of acute vomiting are due to dietary indiscretion, few diagnostics are required and response to symptomatic therapy by correcting the indiscretion or instituting a bland, highly digestible diet for a period of time resolves the vomiting and confirms the diagnosis.