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Why does my dog eat grass?
Training & behaviourPart of · Training & behaviour

Why does my dog eat grass?

6 min read

Good news: a dog that grazes on grass is almost always normal. It's not a sign of illness, not a way of "clearing out", and not a deficiency. Most dogs graze because they like the taste and enjoy exploring. Really, keep an eye on just two things: a treated lawn, and sudden, frantic grazing.

Why he grazes

Grazing is part of a dog's natural repertoire, inherited from the canids who topped up their meals with plants. Two large surveys (Sueda et al. 2008, Hart et al. 2008) followed grass-eating dogs: fewer than 10% showed any sign of illness before eating the grass, and only around one in five vomited afterwards. The taste, the texture and the urge to nose through the ground explain most of it. So you haven't caused anything, and there's nothing to fix.

Calm grazing: all is well

  • He grazes a little on a walk, then heads off to sniff or play.
  • He does it calmly, with no retching or drooling beforehand.
  • He's eating, drinking and generally in good form otherwise.
  • The lawn is neither treated nor full of grass seeds.

Grazing that's worth a closer look

  • He suddenly starts grazing frantically, as if "possessed".
  • He retches, drools or salivates a lot before eating the grass.
  • He often vomits afterwards, or it keeps coming back.
  • He's also started swallowing soil or stones recently.
  • The behaviour is brand new in an adult dog.

Grass itself isn't dangerous. The risk comes from what's on it or around it.

Genuinely to avoid

Treated lawn (weedkiller, fertiliser)Products left on the grass get licked and swallowed along with it.
Slug pellets (metaldehyde)Highly toxic to dogs, with a risk of tremors and convulsions. Keep them out of anywhere he can reach.
Toxic plants mixed in with the grassButtercups, dug-up bulbs, fallen berries: a grazing dog can pick these up along the way.

Keep an eye on

Grass seeds, in summerThese dart-shaped dry seeds catch on and can work their way into the skin, nose or ears.
Soil parasitesSome worms are picked up in soiled grass, which is why regular worming is worthwhile.

No worries

Grass from your own untreated lawnA little grass grazed calmly is digested without any problem.

Eating grass is almost always harmless. Here are the rare cases where it's worth a call.

Keep an eye on

  • Sudden, frantic grazing, with retching or excessive salivation
  • He's grazing far more than usual, all of a sudden

Time to consult

  • Repeated vomiting after grazing
  • Refusing food, low spirits, diarrhoea that sets in
  • He's also started eating soil or stones (recent pica)

Emergency

  • He may have grazed a treated lawn (slug pellets, weedkiller), then trembles, staggers or convulses
  • A swollen, tight belly with efforts to vomit that bring nothing up
  1. Sueda et al. — Characterisation of plant eating in dogs (2008)
  2. Hart et al. — Plant eating in domestic dogs (enquêtes UC Davis) (2008)
  3. Global Gastrointestinal Guidelines, WSAVA
  4. Animal Poison Control Center (plantes et produits de jardin toxiques), ASPCA

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Frequently asked questions

Why does my dog eat grass?

Most often for the taste and the pleasure of exploring (it's foraging), a behaviour inherited from wild canids. In a dog in good form, it's normal and nothing to worry about. Just stay alert to treated lawns and grass seeds in summer.

Why does my dog eat grass and vomit?

Contrary to popular belief, he doesn't graze in order to vomit: in the studies, only around one dog in five vomits afterwards, and it's usually involuntary. That said, sudden, frantic grazing with retching can signal nausea, and a vet's opinion is worthwhile then.

Why does my dog eat grass every day?

Grazing a little each day, calmly, is part of his normal repertoire: plenty of dogs make a small habit of it on walks. No cause for concern as long as he stays in good form. Above all, check that the grass is neither treated nor full of grass seeds.

Is it dangerous for my dog to eat grass?

Grass itself, no. The risk comes from what's on it or around it: weedkiller, slug pellets, fertiliser, toxic plants mixed in with the lawn, and grass seeds in season. On an untreated lawn, calm grazing is digested without a hitch.

My dog grazes: is he clearing himself out or worming himself?

It's a stubborn myth. The observations show that most grazing dogs are not ill beforehand, and grass has no worming effect at all. So there's no point adding fibre or supplementing "to make up for it": you don't supplement blindly.

What should I do if my dog eats grass and vomits often?

If the vomiting keeps recurring, or comes with low spirits, refusing food or blood, the grass is no longer the problem: ask your vet for advice. You can also limit access by working on a calm "leave it" on walks, without ever telling him off.

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