Why does my dog eat grass, and should I stop them?

Many owners worry when their dog starts munching on the lawn. The good news is that grass eating is very common and, in most dogs, perfectly normal. This guide explains what we know about why dogs do it, which old beliefs don't stand up, and the real risks to look out for.

Why do dogs eat grass?

Nobody knows exactly why dogs eat grass, but the evidence points to it being a normal behaviour rather than a sign of a problem.

They like it

PDSA says some dogs eat grass simply because they enjoy the taste or texture.

Boredom

Some dogs nibble grass when they have nothing better to do. Longer or more varied walks, play, sniffing games and food puzzles can help.

It's common, especially in younger dogs

In a US study published in 2008, researchers surveyed owners visiting a veterinary teaching hospital. Of those whose dogs had daily access to plants, 79% said their dog had eaten grass or other plants. A larger online survey in the same study found younger dogs ate plants more often than older dogs.

Do dogs eat grass to make themselves sick?

This is a common belief, but the evidence doesn't support it for most dogs. PDSA describes it as a misconception.

In the online part of the 2008 study, covering more than 1,500 plant-eating dogs:

• only 9% often seemed unwell before eating plants
• only 22% often vomited afterwards
• younger dogs were less likely to seem ill beforehand or to vomit afterwards

So while some dogs do vomit after eating grass, most don't, and most seem perfectly well before they start.

Is my dog missing something from their diet?

Probably not. PDSA says grass eating isn't linked to dietary deficiencies. The 2008 study found no link between how often dogs ate plants and their type of diet, sex, neutering status or breed group.

That said, make sure your dog is eating a complete diet in the right amount. If your dog seems hungry all the time, or is eating lots of things that aren't food, speak to your vet.

Is eating grass bad for dogs?

The grass itself is rarely the problem. The risks come from what is on or in it.

Lungworm

Lungworm is a parasite that dogs catch by eating infected slugs and snails. PDSA explains that this often happens by accident while dogs are eating grass or drinking outside. Lungworm can cause breathing problems, bleeding problems, seizures and even death, and it is now a risk across much of the UK.

Make sure your dog's worming routine includes lungworm protection. PDSA notes that lungworm treatments are only available on prescription, so ask your vet which product to use.

Garden chemicals

Weedkillers and pest killers can harm dogs if swallowed, including when a dog eats a plant that has been treated. Keep your dog off treated areas, follow product instructions, and store chemicals out of reach. PDSA advises against using slug and snail pellets in gardens with pets.

Poisonous plants

Some garden plants can make dogs seriously ill, including daffodils, lilies, yew, autumn crocus and azaleas. If your dog likes to graze, keep an eye on what else they're eating.

Grass seeds

If your dog likes to graze and run through long grass, check them for grass seeds afterwards. PDSA explains that the pointed seeds can lodge in ears, eyes and between toes, and can work their way under the skin. Contact your vet if you think one is stuck.

When to call the vet

Grass eating on its own isn't a reason to see the vet. Contact your vet if your dog:

• seems unwell, quiet or off their food
• eats grass excessively or frantically
• only wants to eat grass and not their normal food
• vomits more than once, or has blood in their vomit
• has diarrhoea that lasts more than two to three days, or any bloody diarrhoea
• has a painful or swollen tummy

Contact your vet immediately if your dog keeps trying to be sick but brings nothing up, especially if their tummy looks swollen. This can be a sign of a twisted stomach (GDV), which is a life-threatening emergency.

Also call your vet straight away if you think your dog has eaten something harmful, such as treated grass or a poisonous plant. Never try to make your dog vomit unless your vet tells you to.

How to stop your dog eating grass

If your dog is healthy and the grass is safe, there's usually no need to stop them. If you'd like them to eat less:

• give them more exercise, play and things to do, such as food puzzles and sniffing games
• teach a "leave it" cue with rewards
• keep them away from areas that may have been treated with chemicals
• keep up with lungworm prevention prescribed by your vet