Can dogs eat grapes? No. Ring us before anything else

What should you do in the next ten minutes?

1. Take away whatever is left and put it somewhere the dog cannot reach. Keep the packet or the bunch: we will want to see it.
2. Wipe out the mouth with a damp towel or flannel, if your dog will let you. Give nothing to eat or drink until you have spoken to somebody.
3. Do not make your dog vomit. Never do it unless a vet or the Animal Poisons Helpline has told you to. In plenty of cases, making an animal vomit does more harm than good.
4. Ring 02 9888 1833 with three things ready: your dog's weight, roughly how many were eaten, and what time it happened. Those three answers decide everything that follows.

How many grapes are dangerous for a dog?

Nobody can tell you, and anybody who gives you a number is guessing with your dog.

The amount needed to do damage is not known. Every estimate that exists was worked out backwards, from dogs who were already sick.

There is a reason it cannot be pinned down. The toxic compound is not spread evenly through the fruit. How much of it a grape carries changes with the variety, the growing conditions and the size of the fruit. Two grapes from the same punnet are not the same dose, and a raisin is a grape with the water taken out.

So the rule we work to is simple. Any amount is worth a phone call, and a small dog that has eaten one grape gets the same conversation as a large dog that has eaten a handful.

Why are grapes toxic to dogs?

For years nobody knew. The best answer we have now is tartaric acid. Grapes carry a lot of it, and dogs are uniquely sensitive to it in a way we are not.

The trail that led there is a good one. Dogs turned up with exactly the same kidney injury after eating tamarind and cream of tartar, and neither of those is a grape. The one thing all three share is tartaric acid.

Note the word likely. This is the best explanation we have, not a closed case. What is not in doubt is the effect: the kidneys are what suffer.

What are the signs of grape poisoning in dogs?

Most dogs who are going to be affected vomit or get diarrhoea within about six to twelve hours. What can follow is a flat dog who has gone off food, seems sore in the belly, is weak or dehydrated, drinks more than usual, and may shiver.

Here is the trap, and it is the reason this page exists. Waiting for those signs is waiting too long. The signs can be delayed, and by the time they show, the damage may already be done. Treated early, most dogs do well.

A dog who ate grapes an hour ago and is bouncing around the kitchen is not a dog who got away with it. It is a dog we still have time to help.

Do sultanas, raisins and currants count?

Yes, and they are the ones people miss, because they arrive inside something else. Fruit toast. Hot cross buns. Christmas cake and pudding. Muesli bars. Trail mix left on a coffee table.

Two more catch people out. Tamarind, which turns up in curry pastes and sauces, and cream of tartar, which is tartaric acid under a friendlier name. Cream of tartar is a common food additive, and it is in some baked goods and in most homemade playdough recipes. Homemade playdough is a genuine and very Australian school-holidays hazard, and almost nobody knows it.

One thing does not count: true currants of the genus Ribes, the blackcurrant and redcurrant kind. They have not been linked to kidney injury in dogs. Dried "currants" in a cake are dried grapes, and those do count. If you are not sure which you have, ring us rather than work it out from the packet.

What happens when you ring us?

Someone will ask your dog's weight, roughly how much was eaten and when. From there we decide whether this is a come-in-now or a watch-at-home, and we would far rather have that conversation than have you decide alone.

If you do come in and it is early enough, the first job is to get what is left out of the stomach before it is absorbed. After that it is a blood test to see where the kidneys are starting from, and usually a period on intravenous fluids to support them, with the bloods repeated so we can see which way things are moving.

Common questions

My dog ate one grape and seems completely fine. Do I still need to ring?

Yes. There is no established safe amount, and a dog who is fine now can still be in trouble tomorrow. The call takes two minutes and it is free.

Can cats eat grapes?

Do not let them. The evidence in cats is much thinner than in dogs: the Animal Poisons Helpline says there are “anecdotal reports of kidney injury in cats ingesting grapes” but less evidence that cats react the same way. Thin evidence is not reassurance, so treat it as a reason to ring.

What if the grapes were cooked, in a cake?

Treat it the same. Cooking removes some of the tartaric acid but not all of it, and a fruit cake also brings its own problems. Ring us.

Where else can I get advice right now?

The Animal Poisons Helpline on 1300 869 738 is a registered charity and free to pet owners. Ring them or ring us. Do not sit and read.

What else is dangerous in my kitchen?

The two other foods people ring us about most are chocolate and onion and garlic, and the same rule applies: ring us first. If your dog is already unwell, ring 02 9888 1833 now.

The Macquarie Veterinary Hospital team

Macquarie Park

Medically reviewed by Dr Michael Stephen, BVSc, MVSc.