It happens often. The causes are many, and often not worrying. Vomiting in dogs is a relatively frequent occurrence. But it is important to know how to distinguish the causes and any underlying problems. The cause of vomiting in dogs can be trivial. The cold, for example, or excessive greediness, or a prolonged period of fasting. Almost always these are sporadic episodes that resolve on their own without even the need for medication. At other times, however, vomiting is the main symptom of a real illness. Acute gastroenteritis, for example, or chronic gastritis — conditions that require the immediate intervention of a vet, whose job it will be to prescribe medication and dietary restrictions.

Why dogs vomit

Dr Cinzia Cortelezzi, a veterinary surgeon from Milan, explains: "It all originates in what is known as the 'vomiting centre': a group of nerve cells located in the brainstem, beneath the hemispheres. It is precisely these cells that, after receiving 'information' from the gastrointestinal tract or from other parts of the body, organise the action of the various organs involved in the vomiting mechanism. Indeed, vomiting does not only involve the stomach, but also the musculoskeletal system, the respiratory system, and even the nervous system. What brings the contents of the stomach back up is a perfect coordination of sudden variations in intra-abdominal pressure, forced inhalations and reversed peristaltic movements." All things that the conscientious owner will have observed more than once in their four-legged companion.

The different types of vomit, yellow or brown

It can happen that our dog vomits immediately after a meal. Or that this occurs after just a few minutes. In most cases, this is regurgitation rather than true vomiting. In these instances, the expelled material takes the form of a slimy, mucous "tube"; the food has not even reached the stomach and is therefore completely undigested.

"The dog may have eaten too quickly," explains Cortelezzi, "or may be in a state of excitement (fear, stress, the presence of females in heat…). The same thing also happens if the dog has ingested grass or other foreign bodies that its system rejects almost immediately. Regurgitation is never of clinical significance if it occurs episodically. It does become significant, however, if it happens frequently (diseases of the oesophagus, compression exerted by this organ on the other intrathoracic organs) or if it appears in a newly weaned puppy. In the latter case, it could raise the suspicion of a congenital malformation, to be investigated immediately with the help of a vet".

The colour (yellow and brown) and the smell of the vomit are, in any case, essential for an accurate veterinary diagnosis. In acute gastric inflammation, vomiting is always a consequence of the ingestion of food (and even water, in the most acute cases): if it appears several hours after a meal, it may raise the suspicion of an intestinal obstruction. In these cases, food cannot "pass through" and comes back up because of a foreign body that, at the gastric or intestinal level, impedes its passage. "Of little significance," the expert adds, "is, by contrast, what is known as 'gastric vomiting' — yellow or brown in colour, with no food material present. This is often the result of nutritional errors. The dog eats too little — perhaps only one meal a day — and its gastrointestinal system reacts to the excessive secretion of gastric juices with this type of vomiting. Sometimes, in such cases, it is enough to give the dog a little dry bread between meals to prevent the vomiting. There is also no cause for concern in cases of vomit that contains streaks of blood. The dog has simply ruptured a small blood vessel in the effort of vomiting." Something that happens to us too, for that matter.

Do consult your vet, however, if the vomit contains dark blood or dark brown biliary fluid. This could be a problem requiring immediate investigation. Furthermore, the smell of urine in the vomit is noted in cases of severe renal failure. Prompt medical intervention becomes, in these cases, essential. The smell of faeces in the vomit, on the other hand, is characteristic of intestinal obstructions located in the final section of the intestine: these are always serious conditions requiring veterinary intervention. In any case — and it bears repeating — if a dog vomits, if diarrhoea is also present and the animal appears lethargic, a visit to the treating vet becomes mandatory.