A little grass never hurts. In fact… sometimes, for our four-legged friends, a craving for tender grass can bring great benefits to the gastrointestinal tract and help expel harmful substances and agents. Meadow grass — the kind we can even sow in our home garden by buying simple packets of common seeds such as ryegrass, barley, valerian or catnip — is particularly appreciated by our animal companions.

Grass can play several roles, even for non-herbivore species, and it carries microorganisms that can enrich the intestinal flora. It is also a privileged source of crude fibre, and always provides valuable nutrients. By ingesting grass stems, dogs are able to cleanse their stomachs, detoxify, and rid themselves of excess gastric juices or any foreign bodies. Cats, on the other hand, can eliminate the fur they ingest through the daily grooming they subject themselves to. In any case, grass performs a beneficial and positive mechanical function.

But what should we do if the cat or dog vomits and keeps eating grass to force the expulsion of whatever is bothering it? And when does this behaviour become compulsive and appear to conceal a more serious problem? Mylav, a veterinary analysis laboratory — with input from Magda Gerou Ferriani, a veterinary surgeon specialising in internal medicine for small animals, and Enrico Bottero, a vet with expertise in cytology of the gastrointestinal and respiratory tract, endoscopy, respiratory diseases and gastroenterology — has sought to take stock of the issue, also offering some useful advice on how to act to prevent the symptom from worsening and becoming serious.

Grass cravings: what they might conceal

As regards occasional grass ingestion followed by vomiting, this should not be considered abnormal if it is a sporadic event. What is entirely abnormal, however, is the continuous eating of grass, associated with fussy appetite and refusal of food, vomiting and lethargy, constant chewing, excessive salivation or licking of surfaces. These last behaviours can, in fact, be an expression of behavioural or organic problems, which need to be distinguished and therefore reported to one's vet as soon as possible.

Frequent episodes of vomiting could, in fact, be symptoms of hyperacidity gastritis, an incorrect or unbalanced diet, allergies or intolerances, or the animal may have ingested a foreign body it cannot rid itself of. Moreover, pancreatitis or liver problems can also manifest through repeated and continuous episodes of vomiting. Conversely, when grass is not chewed properly, its blades tickle the stomach, triggering movement of its walls, those of the oesophagus and those of the intestine. Hence the vomiting, which facilitates the expulsion of undigested food or small foreign bodies such as small stones, plant seeds or fruit stones, if located in the upper part of the digestive tract, and therefore becomes useful for cleansing the gastrointestinal system. Eating grass can also stimulate evacuation through the faeces, if the foreign body is located at intestinal level.

Grass is not, however, merely a strategy adopted by our dogs and cats to stimulate peristalsis. From a behavioural point of view, it can also serve as a form of environmental enrichment for cats bored by a monotonous and solitary indoor life, as well as a useful deterrent to stop them eating houseplants (some of which can be poisonous), or a natural source of folic acid (vitamin B9), essential in the process of haematopoiesis and therefore useful in combating anaemia.

How to manage things day to day

In conclusion, it is worth knowing that eating grass can be something to be considered normal, or a symptom linked to an organic problem, or indeed a simple manifestation of stress, boredom or anxiety. It is useful to remember, for example, that movement of the jaw, and therefore chewing, has very significant physiological consequences: it increases the production of endorphins and serotonin in the brain, with a consequent beneficial effect on mood, and can also lower levels of cortisol and adrenaline, promoting a state of relaxation.

It is essential, however, to distinguish vomiting from simple regurgitation. Vomiting is an act that involves many organs and muscles, has a fairly lengthy build-up and is a sign that may be pathological, but not always. Regurgitation, on the other hand, is sometimes associated with a pathology, despite being less obvious and less dramatic in its presentation and often causing the owner less concern — a mistake, as it should not be underestimated. In the case of regurgitation, the expulsion of matter occurs suddenly, passively, without salivation, retching or abdominal contractions. And so, given that making the right distinctions may not be so straightforward, there is only one piece of advice to remove any doubt: consult your trusted vet if you have any doubts or suspicions that could affect the wellbeing of your four-legged friend.