The Vomiting Dog - Diagnosis

Todd R. Tams, DVM, DAVCIM
VCA West Los Angeles Animal Hospital

Vomiting refers to a forceful ejection of gastric and occasionally proximal small intestinal contents through the mouth. The vomiting act involves three stages: nausea, retching, and vomiting. Serious consequences of vomiting include volume and electrolyte depletion, acid-base imbalance, and aspiration pneumonia.

It is essential that the clinician make a clear differentiation between regurgitation and vomiting at the outset. Regurgitation is defined as passive, retrograde movement of ingested material, usually before it has reached the stomach. Failure to recognize the difference between regurgitation and vomiting often leads to misdiagnosis. Regurgitation may occur immediately after uptake of food or fluids or may be delayed for several hours or more.

Clinical Features Of Vomiting

Because of the wide variety of disorders and stimuli that can cause it, vomiting may present the clinician with a major diagnostic challenge. A complete historical review with emphasis on all body systems is essential for determining a realistic and effective initial work-up plan and treatment protocol. All too often concentration on only the gastrointestinal tract leads to an incorrect diagnosis and inappropriate treatment. Consideration of the following features is useful in assessing and diagnosing a patient with vomiting: (1) duration of signs, (2) signalment and past pertinent history, (3) environment and diet, (4) systems review (e.g., history of PU/PD, coughing and sneezing, dysuria or dyschezia, etc.), (5) time relation to eating (vomiting of undigested or partially digested food more than 8-10 hours after eating often indicates a gastric motility disorder [more common] or gastric outlet obstruction [less common]), (6) content of the vomitus (food, clear fluid, bile, blood, material with fecal odor), and (7) type and frequency of vomiting (projectile?, chronic intermittent?, cyclic?, morning vomiting only?).

Most Common Causes of Acute or Chronic Vomiting in Dogs

First need to Rule-Out:

Dietary problem

•  Indiscretion (e.g., table scraps, garbage ingestion)

•  Food adverse reaction (dietary sensitivity)

•  True food allergy

Parasites

•  Intestinal (including Giardia)

•  Gastric (Physaloptera)

Drug related problems

•  NSAIDS must always be considered

•  Other drugs (e.g., cardiac glycosides, antibiotics, chemotherapeutic agents)

Metabolic disorders

•  Renal disease

•  Liver disease

•  Electrolyte abnormalities

Rule-Outs for Chronic Vomiting, Once the Causes Listed Above are Ruled Out:

Main Categories:

Motility Disorders

•  Gastric hypomotility

Inflammatory Disorders

•  Chronic gastritis

•  Inflammatory bowel disease

Obstructive Disorders

•  Foreign body

•  Hypertrophic gastropathy (uncommon)

Neoplasia

Intermittent Chronic Vomiting

Chronic intermittent vomiting is a common presenting complaint in veterinary medicine. Often there is no specific time relation to eating, the content of the vomitus varies, and the occurrence of vomiting may be very cyclic in nature. Depending on the disorder, other signs such as diarrhea, lethargy, inappetence, and salivation (nausea) may occur as well. When presented with this pattern of clinical signs, the clinician should strongly consider chronic gastritis, inflammatory bowel disease, irritable bowel syndrome, and gastric motility disorders as leading differential diagnoses. A detailed work-up including gastric and intestinal biopsies is often required for definitive diagnosis in these cases. It is important to note that chronic intermittent vomiting is a common clinical sign of inflammatory bowel disease in both dogs and cats.

Vomiting from systemic or metabolic causes may be an acute or chronic sign and generally there is no direct correlation with eating and no predictable vomitus content.

Diagnostic Plan

Vomiting patients in some cases require an extensive work-up, but an organized approach will help to minimize the tests necessary for an early diagnosis. The most important initial considerations in determining what tests to perform are: (1) signalment, (2) acute (less than 3 to 4 days) versus chronic duration, (3) frequency of vomiting, (4) degree of symptoms (mild versus moderate to severe illness, i.e., life threatening, (5) other clinical signs (e.g., shock, melena, abdominal pain, etc.) and (6) physical examination findings. If reasonable concern is established, then a minimum data base of CBC, biochemical profile (or specific tests for evaluation of liver, kidney, pancreas, electrolytes), complete urinalysis (pre-treatment urine specific gravity extremely important for diagnosis of renal failure), and fecal examination is essential. Survey abdominal radiographs are indicated if thorough abdominal palpation is not possible or suggests an abnormality (e.g. foreign body, pancreatitis, pyometra). Unfortunately these tests are often not done early enough. Even if baseline results are unremarkable they are more than justified because they help to rule out serious problems at the outset (e.g., vomiting due to renal failure, diabetes mellitus, liver disease). Alternatively, any abnormalities provide direction for initial treatment and further diagnostics.

The decision for performing more in-depth diagnostic tests is based on ongoing clinical signs, response to therapy, and initial test results. These tests include ACTH stimulation to confirm hypoadrenocorticism in a patient with an abnormal Na:K ratio or to investigate for this disorder if electrolytes are normal, complete barium series or BIPS study (for gastric or intestinal foreign body, gastric hypomotility, gastric outflow obstruction, partial or complete intestinal obstruction), and serum bile acids assay (to assess for significant hepatic disease). Barium swallow with fluoroscopy is often necessary for diagnosis of hiatal hernia disorders and gastroesophageal reflux disease. Serum gastrin levels are run if a gastrinoma (Zollinger-Ellison Syndrome) is suspected.

One of the most reliable and cost efficient diagnostic tools currently available for evaluation of vomiting is fiberoptic endoscopy. Endoscopy allows for direct gastric and duodenal examination, mucosal biopsy from these areas, and in many cases gastric foreign body retrieval. Endoscopy is considerably more reliable than barium series for diagnosis of gastric erosions, chronic gastritis, gastric neoplasia, and inflammatory bowel disease (a common cause of chronic intermittent vomiting in dogs and cats). It is stressed that biopsy samples should always be obtained from stomach and whenever possible small intestine regardless of gross mucosal appearance. Normal gastric biopsies may support gastric motility abnormalities, psychogenic vomiting, irritable bowel syndrome, or may be noncontributory (i.e., look elsewhere for diagnosis). Many dogs with vomiting due to inflammatory bowel disease have no abnormalities on gastric examination or biopsy. If only gastric biopsies are obtained, the diagnosis may be missed.

Ultrasonography can be useful in the diagnostic work-up of a number of disorders that can cause vomiting. Among the problems that may be detected with ultrasonography are certain disorders of the liver (e.g., inflammatory disease, abscessation, cirrhosis, neoplasia, vascular problems), gall bladder (cholecystitis, choleliths), GI foreign bodies, intestinal and gastric wall thickening, intestinal masses, intussusception, kidney disorders, and others. Needle aspirations and/or biopsies can be done at many sites under ultrasound guidance.

Abdominal exploratory is indicated for a variety of problems including foreign body removal, intussusception, gastric mucosal hypertrophy syndromes, procurement of biopsies, and for resection of neoplasia.

References

1.  Burrows CF. Vomiting and regurgitation in the dog: a clinical perspective. Viewpoints in veterinary medicine. Lehigh, Pennsylvania: Alpo Pet Center, 1990; 18-38.

2.  Tams TR. Vomiting, regurgitation, and dysphagia. In: Ettinger SJ, ed., Textbook of veterinary internal medicine. Philadelphia: WB Saunders Co., 1989; 27-32.

3.  Tams TR. Gastrointestinal symptoms. In: Tams TR (ed.), Handbook of Small Animal Gastroenterology. Philadelphia: WB Saunders Co., 1996;1-73.