Vomiting (emesis) is defined as the ejection of food and/or fluid from the digestive tract (mouth, oesophagus, or stomach) and is a common clinical sign in dogs.
Vomiting should be distinguished from regurgitation (ejection of undigested food from stomach immediately after eating) which has different underlying causes.
One-off vomiting, or intermittent vomiting once a week, is not necessarily a disease state in dogs.
Vomiting in dogs is of concern if it occurs more frequently than once every three or four days, contains blood (hematemesis) or parasites.
- Common causes of vomiting include:
- Binge eating or garbage eating, associated with consumption of spoiled food (with subsequent risk of tremorgenic mycotoxicosis)
- Helicobacter spp gastritis - rising prevalence due to increased awareness of disease
- Food allergy - usually in healthy dogs 1 - 2 hrs post-meal, responsive to prednisolone or chlorpheniramine
- Chronic renal disease - usually dog over 8 years of age
- Parasites - e.g. stomach worms (Physaloptera spp, Spirocerca lupi) or lower-gut parasites (e.g. Neospora spp, Giardia spp)
- Rare causes of vomiting include:
- - Infectious - Histoplasma spp, Aspergillus spp, mycosis, and bacterial overgrowth
- - metabolic diseases - hepatitis, hypoadrenocorticism, pancreatitis, ketoacidosis, metabolic acidosis, electrolyte abnormalities (e.g., hypokalemia, hyperkalemia, hyponatremia, hypercalcemia)
- - Nervous - cerebral edema, CNS tumor, meningoencephalitis, vestibular syndrome, otitis media, labyrinthitis
- - Congenital - pyloric stenosis
- - Neoplastic - gastric adenocarcinoma, pancreatic adenocarcinoma, lymphoma, fibrosarcoma, polyps, gastrinoma, and mast cell tumors
- - Irritable bowel disease - lymphocytic, plasmacytic, and eosinophilic gastritis, enteritis, and colitis
- - Miscellaneous - motility disorders, intussusception, lymphangiectasia, gastrointestinal surgery, drugs (e.g., NSAIDs and glucocorticoids), gastric duodenal ulcer disease, congestive heart failure, and chronic foreign body
- - Infections - heartworm disease
- - Hepatitis, cholecystitis, cholangiohepatitis
- - Hyperthyroidism
In dogs, the chemoreceptor trigger zone is the primary centre for initiation of emesis, located within the reticular formation system.
Treatment involves primary addressing the underlying cause of vomiting which may be difficult to establish in many cases. Use of antiemetic drugs may alleviate symptoms without eliminating the cause.
Palliative treatment with antiemetic drugs, while ethical, must be augmented with evidence based medicine, where accurate diagnosis through logical elimination of possible causes helps establish an effective and curative treatment regimen.