Grapes of wrath…or raisins if you choose

Such sweet, sweet juicy delights can be a dangerous feast for a curious pup.  Grapes and raisins are not something most people would associate with poisons, however, in the wrong belly they can present a serious danger.  Once used as a sweet training tool, today, the grapes should be hidden from your pup instead, lest they are one of the few who react negatively to the fruit.

We have recently had a spate of grape and raisin ingestions seen at the hospital.  Fortunately, all cases were fine and none of our patients developed harmful consequences.  But it got me thinking about the knowledge gap that surrounds commonly accessible household foods and other items that may pose a risk to pets.  I know of many friends and clients whose dogs often eat grapes and do not suffer any ill effects.  However, in the wrong bellies, grapes and raisins have the potential to cause a life threatening acute kidney failure.

How does this happen?  This is what we still do not know, and it is only the past decade or so that grape toxicity has even become a recognised problem.  The actual mechanism of toxicity is not clear and various studies have been performed to try to identify the toxic agent.  Various theories have included a toxin in the skin, in the pulp, or even involving the pesticides used in production.  A more recent study has suggested that one of the sugars may be at fault.  The weird thing is that only a handful of animals will have severe reactions, so it is considered an “idiosyncratic reaction”.  An idiosyncratic reaction is one which occurs rarely and unpredictably, so it may occur in one pet and not another.  There is some thought that a certain amount of grapes need to be eaten but this is not well known either.

At the end of the day, whether or not your dog will react is unpredictable, so the best course of action is to avoid grapes and raisins all together but if exposed, seeking veterinary advice is a must if you wish to avoid potentially losing your friend.

Baskin, one of my recent patients who ate a couple of grapes.  He had intravenous fluids for two days and went well.

Baskin, one of my recent patients who ate a couple of grapes but thanks to committed owners, he recovered uneventfully.

What might happen?  The initial sign that your dog might not be tolerating the grapes may be the development of vomiting within the first couple of hours after exposure, followed by diarrhoea, lethargy and increased thirst over the following 5-6 hours.  Kidney failure can develop during the next 1-3 days and may cause further depression, gastric signs and weakness.  At this point, treatment may not be successful since kidney failure can be rapid and irreversible following acute toxic injury.  It is possible that the earlier signs may not be seen prior to the onset of significant kidney damage so it may not be a good idea to wait, just in case.

Treatment can be commenced from the time of ingestion and ideally your dog should be seen within 2 hours of ingestion so that your vet can make it vomit up the grapes.  After emesis, activated charcoal is given either in food, or by messily syringing into your dog’s mouth.  The charcoal may bind to the toxin, and I say may, because we don’t know what the toxin is so can’t be sure that it will bind to charcoal.  However, this is standard decontamination procedure and is unlikely to lead to any harm.  Gold standard treatment is to admit all animals who eat grapes into hospital to administer intravenous fluids for 48 hours so as to support kidney function.  Kidney enzymes should be examined at the commencement of treatment and followed up over the following 72 hours to ensure they remain normal and ensure the kidneys have not received a significant insult.

So is treatment absolutely necessary?  Essentially deciding to do nothing is potentially putting the pet’s life at risk and the outcome could be dire.  Appropriately treated, animals respond well, so difficulty to know whether they would have reacted or not.  Is it worth the risk?


3 thoughts on “Grapes of wrath…or raisins if you choose

  1. Annie buden says:

    Hi cheryl. We have this problem a bit down here on the mornington peninsula at vintage time. We have wine makers’ dogs who can eat bunches and bunches straight off the vine with out any illness. and other dogs who do indeed get sick.. Wondering if it has to do with the tannins in the skins and pips. Some varieties of grapes have more tannins than others and tannins vary with ripeness. Interesting condition. Would be great to have someone solve this mystery one day. Cheers Annie

  2. Paul Eubig (veterinarian) says:

    Very good summary of what is known vs. unknown about grape and raisin ingestion in dogs. I have always advocated being proactive because if kidney failure develops then it can be a miserable death for the dog. Thank you.

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