Grape and raisin poisoning and toxicity in dogs

Among the plethora of foodstuffs and common household substances that can prove poisonous to dogs, grapes and raisins are some of the most frequent causes of sickness and toxicity in pets. Grapes or raisins are food staples in many households, and unlike many other potential poisons, are also palatable to many dogs and do not provide a bitter or distasteful warning flavour to them to discourage dogs from eating them.

As well as grapes and raisins, sultanas can also potentially prove toxic to dogs, depending upon their source, as some sultanas are produced from a variety of black grapes too. Raisins are, of course, grapes in their dried format, hence the toxicity and risk for consumption of raisins is the same as with grapes, and can in fact prove more serious as raisins are dried and concentrated.

It is important to keep grapes, raisins and related products out of your dog’s reach, never to feed them as a treat, and to remember that as well as the raw product itself, many cakes and biscuits that your dog might enjoy eating will contain raisins or other similar dried fruits too.

Why are grapes and raisins poisonous to dogs?

The exact reason for why grapes and raisins are poisonous to dogs is not known, and the precise ingredient or compound within these fruits that causes toxicity has not been identified. For many years, the idea of grape and raisin toxicity in dogs was considered to be an urban myth or old wives tale, however veterinary professionals are now unanimous in their opinion that grapes and raisins can indeed be poisonous to dogs.

The other issue for why identifying grape or raisin toxicity in dogs can be hit or miss is the fact that there is no formula or dosage table that shows exactly what amount of grapes or raisins might be toxic to any given dog. Some dogs become very sick after ingesting just a few grapes or raisins, while others have been known to consume significant quantities of these fruits with no ill effects.

When grape or raisin consumption does prove toxic to dogs, it manifests itself as renal failure, or sudden kidney failure, accompanied by a failure of the kidneys to produce urine.

Symptoms of grape or raisin toxicity in dogs

It is important to be alert to the possibility of grape or raisin toxicity in your dog, as grapes and raisins are so common and readily available, even if you do not keep them within your own household. Symptoms of grape or raisin toxicity in dogs usually develop quickly, and can soon prove serious and critical. Suspected grape or raisin toxicity in dogs is a veterinary emergency, and requires immediate treatment.

Signs and symptoms to be alert for include:

• Sickness including vomiting and general digestive discomfort
• Diarrhoea or loose stools. Evidence of raisins or grape skins may also be visibly present in the stools
• Loss of appetite and disinterest in food
• A subdued demeanour, lethargy and apparent weakness
• Pain in the stomach and abdomen
• Dehydration, despite drinking water
• Straining to urinate or not passing much urine
• A total stoppage of urination and total failure to urinate

Diagnosing and treating grape or raisin poisoning in dogs

Ingesting grapes or raisins, even if symptoms have not begun to prevent themselves, requires urgent veterinary treatment and it is important not to delay seeking help. Waiting to see if symptoms manifest within your dog before calling your vet can make treatment more difficult and decrease your pet’s chances of survival.

When you arrive at the vets with a dog that has eaten or is suspected to have eaten grapes or raisins, your vet will almost certainly induce vomiting in your dog immediately, to remove any remaining undigested raisin or grape matter within the stomach. If your vet is some distance away or advises you to do so over the phone, you may even need to induce vomiting at home, although you should never attempt to do this without speaking to your vet first, and should always do so exactly in line with your vet’s instructions. You vet may also administer activated charcoal to your dog, to absorb any grape or raisin matter that remains in the stomach.

Your vet may perform blood tests on your dog to identify the condition of the kidneys, and administer IV fluid therapy and medications to stimulate urine production.

In some cases where the condition is acute and directly affecting the kidneys, dialysis may be required as well.

The prognosis for dogs that have consumed grapes or raisins

Treating grape or raisin toxicity in dogs can be challenging, and the goal of early treatment is to prevent kidney failure from occurring. The prognosis for dogs whose kidneys have become affected is guarded and often poor. If early treatment is sought and the majority of the grape or raisin content can be removed from the stomach by means of inducing vomiting before digestion, avoiding or minimising the effects of damage to the kidneys may be possible.

Grape or raisin ingestion in dogs should be treated as an emergency, and can prove fatal. Familiarise yourself with the symptoms to look out for, keep grapes and raisins away from your dog, and always have the number of your vet to hand just in case of any emergencies.