Why do dogs and cats eat grass?

I take Ruff out every morning and watch him eat the dew off the grass and the long blades of grass almost every morning – he loves grazing like a cow!

There are two main types of canine grass eating. The first is simple grazing where your dog happily munches on grass and suffers no ill effects.

Sometimes it may be to make up for a nutritional deficiency but even dogs that eat well balanced diets will eat grass. It’s possible that they simply like the taste and the sensation. It’s like a fresh salad to them. So even if you’re feeding your dog well, they might still fancy some greens!

Instinctive vomitting behaviour

The other type of grass eating is when a dog eats some grass and throws it up. This is thought to be a deliberate instinctive attempt to induce vomiting after they’ve swallowed something that makes them feel ill or disagrees with them.

Dogs that eat to make themselves vomit usually swallow grass as quickly as possible, barely even chewing it. It is believed that the long, unchewed pieces of grass stimulate their throats to bring on the vomiting reaction.

If your dog eats grass then vomits and seems fine, they have probably instictively taken care of whatever their intolerance was.

Parasites could be another reason

A team at the University of California, Davis, School of Veterinary Medicine believe that regular plant eating by our pets is a reflection of an innate predisposition of regular plant eating by wild ancestors, which is supported by numerous reports of wild carnivores eating plants, as shown mostly by the non-digestible grass and other plant parts seen in their scats (the researchers name for poo!)

Studies on primates have revealed non-digestible plants purge the intestinal system of worms and other parasites.

Given virtually all wild carnivores carry an intestinal parasite load, regular, instinctive plant eating would have an adaptive role in maintaining a tolerable intestinal parasite load, whether or not the animal senses the parasites.

The findings were presented at the annual Congress of the International Society for Applied Ethology in Bergen, Norway.

As reported in the journal Science, the team’s advice is to buy or grow some indoor grass for cats to chew on. This will give them a chance to exercise this innate behaviour with a safe source of non-poisonous plant life.

I happily allow Ruff to be a cow-dog and fulfil his ancestral instincts on our morning walks even though he is regularly wormed😊