Vomiting is a prevalent problem in cats. Occasional episodes of vomiting in an otherwise healthy-looking cat generally do not warrant a thorough work-up. However, if vomiting occurs more frequently or if other clinical signs are present, a more in-depth examination is recommended. In cats, vomiting can be associated with a wide variety of diseases, probably because of the high number of peripheral (essentially abdominal) receptors that can stimulate the vomiting centre in the brainstem in that species. Moreover, the close association between the vomiting centre and the chemoreceptor trigger zone located on the floor of the fourth ventricle plays an important role when cats experience metabolic disorders or intoxications. Principally, it is helpful to differentiate between causes originating from the gastrointestinal (GI) tract and those from other organ systems (Figure 1). Causes of acute and chronic vomiting largely overlap; therefore both presentations will be discussed together.

Diagnostic Approach

In cases requiring veterinary attention (as defined above), a good history can be very helpful in tracking hints revealing the presence of diseases outside the GI tract. A detailed physical examination is performed to assess the severity of the consequences of vomiting (dehydration, weight loss) and search for additional clinical signs associated with vomiting such as icterus, anaemia, etc. A thorough oral examination should always be performed, in particular in animals prone to play with potential foreign bodies (look for a piece of string looping around the base of the tongue). Thorough palpation of the ventral neck on both sides of the trachea can help detect enlarged thyroid glands. Additionally, cardiac auscultation may reveal gallop rhythm or other findings associated with thyroid toxicity. Although exceptions may occur, most hyperthyroid cats are 7 years of age and older. Absence of palpable masses or cardiac changes is not sufficient to rule out hyperthyroidism. Finally, the abdomen must be thoroughly palpated to detect possible pain, space-occupying lesions, intussusception, abnormal intestinal loops, kidneys of abnormal size, etc.

Figure 1. Causes of vomiting in the cat.

 Gastrointestinal:

 Stomach:

 Infectious (viral, bacterial, parasitic)

 Obstructive (including bezoars)

 Adverse reaction to food (food intolerance or food allergy)

 Chronic gastritis (poss. with inflammatory bowel disease IBD)

 Gastric nematodes

 Gastric neoplasia

 Motility disorders

 Small bowel:

 Infectious (viral, bacterial, parasitic)

 Obstructive (including linear foreign body, intussusception)

 Adverse reaction to food (food intolerance or food allergy)

 IBD

 Intestinal neoplasia

 Ileus (of different causes)

 Colon:

 Severe constipation

 Not gastrointestinal:

 Abdominal:

 Peritonitis (e.g., feline infectious peritonitis (FIP))

 Liver disease (including biliary tree)

 Pancreatitis (vomiting occurs rarely in cats)

 Diaphragmatic hernia

 Neoplasia

 Metabolic:

 Uraemic syndrome

 Endocrine disease (hyperthyroidism, diabetic ketoacidosis)

 Drugs, toxins (antibiotics, non-steroidal antiinflammatory drugs (NSAIDs), toxic plants, etc.)

 Cardiomyopathy with congestive heart failure

 Dirofilariasis

 Sepsis

 Systemic mastocytosis

 Neurological:

 Motion sickness

 Vestibular disorders

 Encephalitis

 Dysautonomia

 Increased intracranial pressure

 Psychogenic (excitation, fear, pain)

Recommended ancillary tests may differ from patient to patient based on the information obtained from history and physical examination, and the likely anatomical localisation of the problem causing vomiting. Useful tests in patients with suspected alimentary tract disease include diagnostic imaging of the abdomen. Radiographs are always indicated in vomiting animals, as they are quite sensitive and specific for the diagnosis of intestinal obstructions and linear foreign bodies. If survey radiographs are not diagnostic in a cat suspected of having an obstructive lesion, radiographic contrast may be administered to allow better visualisation. However, the risk of aspiration of the contrast agent should be carefully weighed against the possible benefits from the study.

Additionally, abdominal ultrasonography can be very useful as a complement to radiographs: foreign bodies, intestinal masses, intussusceptions, abnormalities in wall layering and many more lesions can easily be detected by an experienced ultrasonographer.

Cats with chronic vomiting, inappetence and weight loss may be suffering from adverse reaction to food or idiopathic inflammatory bowel diseases (IBD). If the cat's condition allows it, switching to an elimination diet with a novel protein or a hydrolysed peptide diet may have both diagnostic and therapeutic value. Faecal parasitological examination should not be neglected (mostly to rule out the presence of intestinal worms; gastric worms such as Ollulanus tricuspis and Physaloptera rara are more of a diagnostic challenge). In some instances all the above examinations are either normal or inconclusive.

If extra-GI causes could be excluded (see below) and the problem still seems to originate from the GI tract, gastroduodenoscopy may be indicated to visualise the gastric and duodenal mucosa, and perform mucosal biopsies for histological analysis. Alternatively, exploratory abdominal surgery enables the surgeon to explore the whole bowel as well as the abdominal cavity, and to sample transmural biopsies from abnormal looking intestinal segments or other organs. Finally, a full complete blood count (CBC) and chemistry panel are useful to check for severe consequences of acute or chronic vomiting. Anaemia, leucocytosis or leucopenia may be present in association with various diseases. Electrolytes may be depleted (hypokalaemia) and hypoalbuminaemia or panhypoproteinaemia can be present (if so, check for renal loss with urine protein to creatinine ratio). It is advisable to check serum cobalamin (vitamin B12) concentrations in cats with chronic IBD, as it may be low and the cat may require substitution therapy.

For cats with disease likely to originate outside the alimentary tract, a broad search must be initiated. Practically, a stepwise approach is meaningful. The first step consists of a minimal database including CBC, chemistry panel and urinalysis, as well as retrovirus check and, if the cat is older than 7 years of age, a serum thyroxine concentration. After these results are available, a more targeted approach based on the abnormalities detected in the lab work is often possible. Diagnostic imaging of thorax and abdomen (including abdominal ultrasound examination) can be very helpful to confirm or rule out diseases affecting the liver, the kidneys, possibly the pancreas (although only a minority of cats vomit due to pancreatitis) or other organs.

Basic Therapeutic Guidelines

Depending on the cat's condition, treatment is initiated in some or all of the following categories.

 Supportive treatment, essentially intravenous fluids, often with electrolyte replacement (e.g., potassium).

 Symptomatic treatment: anti-emetics such as metoclopramide 0.3-0.5 mg/kg s.c. q8h or as an intravenous constant rate infusion of 1-2 mg/kg in 24 hours. Gastric mucosal protection: we currently use famotidine 0.5 mg/kg orally or s.c. once daily. Other H₂-blockers may be used as well such as ranitidine 0.5-2 mg/kg orally or s.c. q12h. Consider adding sucralfate 0.5 g per cat q6-8h if erosive or ulcerated gastritis is suspected. Feed a bland or a hypoallergenic diet (see above).

 Specific treatment can be initiated when the disease has been identified.

References

1.  Daminet S. Vomiting, acute and vomiting, chronic. In: Côté, E. ed. Clinical veterinary advisor--dogs and cats. St. Louis, Mosby Elsevier, 2007; 1157-1160

2.  Zoran D. The cat with signs of acute vomiting and the cat with chronic vomiting. In: Rand, J. ed. Problem-based feline medicine. Philadelphia: Elsevier Saunders, 2006; 630-690.