Grapes are toxic to dogs

Both grapes and raisins, i.e. dried grapes, are highly toxic to dogs. They can cause acute kidney failure (acute renal failure) in dogs, which can be fatal. How many grapes or raisins are already toxic for my dog? What symptoms does the dog show when poisoned with grapes and what do I do then?

Sultanas and currants are raisins derived from different grape varieties. They are also highly toxic to dogs. Sultanas contain the substance that is toxic to dogs in higher concentrations per gram.

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Which substance in grapes and raisins is toxic (poisonous) for dogs has not yet been finally clarified scientifically.

In any case, grapes contain oxalic acid and oxalate (dicarboxylic acids), which can irritate the mucous membranes of the mouth as well as cause nausea, vomiting, stomach pain and diarrhoea in dogs.

However, it has not yet been scientifically researched why the consumption of large quantities of grapes or raisins can lead to acute kidney failure in dogs. This is an unknown toxin whose effect on the body has been researched, but only theories exist as to its exact mechanism. While some dogs hardly react to the ingestion of grapes, it can have fatal consequences in others.

It has been found in experiments that in most dogs a so-called hypercalcaemia occurs in the blood serum after ingestion of grapes. The calcium level rises sharply in the blood and this can lead to kidney failure.

Another theory suspects anaphylactic shock due to the increase of urea and creatinine in the blood serum, which has also been observed in dogs after ingesting grapes.

Some veterinarians also suspect that the symptoms of poisoning from grapes and raisins in dogs may be due to pesticides whose residues are found in the grapes. But this theory is also not proven.

How many grapes or raisins will poison my dog?

Since the toxic substance in grapes and raisins is not known and dogs react very differently to the ingestion of grapes, it is not yet possible to determine a specific lethal dose.

However, it is certain that even small amounts can lead to symptoms of poisoning in some dogs. This is because dogs react differently to the poison. It is also certain that a smaller dose leads to symptoms of poisoning in small dogs than in large dogs. Logical: The dose must always be seen in relation to the dog's body weight.

According to current knowledge, however, it is assumed that 10-30 grams of grapes per kg body weight of the dog can be sufficient to kill the dog.

Raisins, currants and sultanas: concentrated poison

Raisins and also sultanas and currants have a higher concentration of the poison per gram. If we assume that 25 grams of sultanas are created from approx. 100 grams of grapes, then already a quarter of the dose of grapes of sultanas is lethal for the dog.


What are the signs of grape or raisin poisoning in dogs?

The following symptoms may occur if a dog is poisoned with grapes, raisins, sultanas or currants:

  • increased salivation and burning sensation in the mouth
  • severe gastrointestinal problems: nausea, loss of appetite, stomach pain, vomiting and diarrhoea
  • lethargy
  • kidney problems: decreased urine output to the point of urine failure.
  • death may occur due to kidney failure


How to treat grape poisoning in a dog?

In case of acute poisoning with grapes or raisins, you should go to the vet immediately and call him beforehand. This will ensure that the vet is available and can prepare for the case. They might be able to give you advice over the phone. In case of poisoning, every minute counts to prevent the poison from getting from the stomach into the blood and possibly causing irreparable damage.

Unfortunately, there is no antidote for grapes and raisins. Your vet will try to remove the grape toxin from the dog's body. There are different methods to do this, but they are only successful in the first 2 hours after ingestion of the grapes. For example, by administering activated charcoal, the poison can be bound in the gastrointestinal tract and excreted with the faeces.

Use charcoal to bind the toxin in the body and eliminate it

The best thing you can do, in consultation with your vet, is to give the dog charcoal tablets or, even better, activated charcoal dissolved in water directly as soon as possible after ingestion of the poison, so that the poison is bound in the gastrointestinal tract and does not pass into the blood.

Activated charcoal administration: dosage and preparation

  • Dissolve 1-4 g of activated charcoal per kilogram of bodyweight in water
  • 5ml of water per gram of activated charcoal
  • Give the activated charcoal solution directly to the dog

Your vet can use a variety of medications to induce vomiting in the dog to remove the toxin from the body. If the poisoning is severe, the vet will try to control the symptoms of the kidneys with infusion therapy, and if the kidneys are severely damaged, with dialysis and medication. This can take up to 72 hours.

However, the first symptoms of grape poisoning may appear within the first few hours after ingestion of the poison. In case of severe poisoning, death may occur after 2-3 days.


What is the prognosis in case of grape poisoning in dogs?

In the case of poisoning with grapes or raisins, dogs react very differently to the poison. Also, the prognosis depends not only on the individual reaction of the dog, but also on the dose, the size and the general condition of the dog.

Unfortunately, the prognosis is often poor or even very poor in cases of severe poisoning with grapes where the kidneys are affected. Immediate treatment is important. In the first two hours after ingestion of the grapes or sultanas, the chances are much better.


Keep grapes and raisins away from the dog

There are different ways for dogs to reach grapes or sultanas. Raisins, sultanas and currants taste sweet, so they attract some dogs.

Thus, dried grapes are present in many sweets such as cakes and biscuits:

  • Muesli
  • Cake
  • Biscuits
  • Stollen at Christmas time
  • Buns
  • Trail mix
  • Bars

Of course, special care should also be taken when walking near vineyards! Not only could the dog eat the grapes here, but the vineyards are also fertilised with residues from the pressing of the grapes (pomace).

Therefore: educate all family members and people who look after your dog that grapes and raisins can be very toxic for the dog. Ask everyone not to leave them open in the house, in the car or in the garden! Especially at Christmas, there are many sweets with raisins. Unfortunately, the most common poisonings are with raisins, but of course also with chocolate.

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