Raisins, currants, sultanas and grapes (Vitis vinifera fruits) can be extremely toxic to dogs. Both fresh grapes and dried fruits can cause severe kidney damage, regardless of the dog's size, breed, or age. Even a small amount can be dangerous. If you suspect your dog has eaten raisins, grapes, currants, sultanas contact your veterinary practice as soon as possible. There is no way of knowing which dogs will have adverse effects from raisin ingestion, so vets have to presume that a dog will suffer toxic effects and will assess each case accordingly. For the purposes of this factsheet, the term “raisin” is used to encompass all Vitis vinifera fruits.

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It is thought that the tartaric acid within these fruits is what causes the toxicity, but there is a lot of individual variation between dogs as to how much constitutes a toxic dose. Some dogs can become very ill after eating a small number of raisins, whereas others might eat a large quantity of this fruit and have minimal effects. In the body, tartaric acid is eliminated by a transporter molecule called OAT-4. As dogs lack OAT-4 in their kidneys, the tartaric acid accumulates in their kidneys and causes cell damage. The amount of tartaric acid in Vitis vinifera fruits also varies by variety, environmental growing conditions and state of growth.

Ideally treatment should be started before signs of toxicity appear, so contact your vet as soon as you realize that your dog has eaten raisins. The first signs of raisin poisoning typically appear within 6 to 24 hours after ingestion. Your dog may start vomiting, show signs of diarrhea, and become unusually lethargic or tired. Signs of kidney damage usually appear between 24-72 hours after they have eaten the raisins, and may progressively get worse if your dog does not receive prompt treatment at a veterinary practice. You may notice your pet drinking more water than usual. They may urinate more frequently or less frequently than usual or stop producing urine altogether. Some dogs might also show signs of abdominal pain, appearing hunched over or sensitive when touched around their belly area.

Dogs experiencing raisin toxicity may experience gastrointestinal effects and serious kidney damage. Your veterinarian will assess the treatment your pet needs based on how long it has been since the fruit/dried fruit was ingested, how much was ingested, any pre-existing conditions your dog has and their clinical appearance and blood tests. In most cases your vet will give your dog an injection to make them vomit –to remove any raisins etc from their stomach. Vomiting can be helpful up to 12 hours after ingestion of raisins. They will perform a physical examination and likely run blood tests to check your dog's kidney function. If your pet has a pre-existing kidney disease, raisin toxicity may affect them more severely. Some dogs will need to stay at the veterinary hospital for 48 hours after ingestion of raisins to receive fluid therapy through an intravenous drip. This helps support kidney function. Your dog may also be given anti-nausea medication and pain killers if deemed necessary.

The outcome varies hugely between individual dogs and is also dependent on how quickly treatment begins and how many raisins were consumed. Dogs that receive immediate treatment generally have a better prognosis. However, if kidney damage has already occurred, the situation becomes more serious. Some dogs may develop long-term kidney problems or complete kidney failure. In severe cases, Vitis vinifera fruit poisoning can be fatal, although this is rare.

Contact your veterinarian immediately if you know or suspect your dog has eaten any number of raisins, grapes, currants or other Vitis vinifera fruits. This is always an emergency – do not wait to see if symptoms develop. There is no known dose for this type of toxicity and therefore some dogs develop toxicity from a very small ingestion, whereas others remain seemingly fine despite ingesting larger numbers of fruit. Regardless, quick action can make the difference between a successful recovery and serious complications. Even if your dog seems fine, the toxic effects might not be visible yet, and early treatment is crucial for the best outcome. Each case should be assessed on an individual basis.

Prevention is absolutely essential. Keep all raisins, currants, grapes, and foods containing these ingredients (like cookies, cakes, mince pies, cereals, and trail mix) completely out of your dog's reach. Store these items in sealed containers in closed cabinets. Inform all family members, including children, about the dangers of giving dogs Vitis vinifera fruits as treats. When eating these foods yourself, be careful not to drop any pieces where your dog might find them. This is particularly important with young children who often eat these healthy snacks but may be more likely to drop food – a baby gate can help in these situations to remove your dog from cleaning up any food spillages!