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The most tragic accidents are those that could have been avoided. I’ve written about the danger that grapes and raisins pose to dogs before over on Nutrition Nuggets, but in honor of Ted, an eight-year-old Maltipoo who is no longer with us, I’d like to bring up the topic again.

Grapes and raisins can cause kidney failure in dogs, but until recently, veterinarians weren’t aware of this connection. I’m sure that some of the cases of kidney failure I’ve treated in the past were due to grape or raisin ingestion, but I didn’t even know to ask the question, “Could your dog have eaten grapes or raisins?”

Ted’s story is emblematic. He was a much loved member of a family that included two young children. As anyone who has spent time with the toddler/preschool set knows, their snacks stand about an equal chance of being swallowed or landing on the floor, being buried under the couch cushions, etc. Ted’s owner is sure that at any given time a few raisins could have been found scattered about the house. Ted was probably eating them for some time.

When Ted was seen by a veterinarian, he was suffering only from gastrointestinal upset. No one was overly concerned at the time. But as his condition deteriorated and evidence of kidney failure was found on a panel of blood work, the severity of his situation became evident. His veterinarian asked about exposure to potentially nephrotoxic (damaging to the kidneys) substances — antifreeze, bodies of water that could contain Leptospira bacteria, some types of medications … and grapes/raisins. That’s when the pieces all fell into place. Despite heroic efforts to save him, Ted’s condition declined to the point where the only humane option that remained was euthanasia.

Here’s what we currently know about grape and raising toxicity:

  • The causative agent, which has not yet been identified, appears to be in the flesh of the fruit. Peeled grapes or seedless varieties don’t appear to be any less toxic.
  • Raisins are more dangerous than grapes, probably because they are dried and are therefore a more concentrated source of the toxin.
  • There is a lot of variation in how individual dogs react to eating grapes. Some can ingest relatively large amounts with no adverse effects, while in others very small exposures can lead to big problems.
  • Cats also appear susceptible, but since most cats aren’t interested in eating grapes or raisins we don’t see as many problems in this species.

Initially, dogs that have eaten grapes or raisins may experience nausea and vomiting followed by diarrhea, increased thirst and urination, and lethargy. If the kidneys continue to shut down, urine production may slow and eventually stop altogether. Bad breath and oral ulcers develop as uremic toxins buildup in the body, and affected dogs can finally lapse into a coma and die.

If you know that your dog has eaten grapes or raisins, call your veterinarian immediately. Inducing vomiting within a few hours of ingestion can remove some of the toxin before it enters the bloodstream. The oral administration of activated charcoal can also help bind the toxin and prevent its absorption. Treatment for kidney failure centers on intravenous fluid therapy to support kidney function and flush toxins from the body and symptomatic care (e.g., anti-nausea medications and gastric protectants to prevent or treat stomach ulcers). Mild to moderately affected individuals will usually recover with appropriate care, albeit with permanently reduced kidney function. If urine production stops, the prognosis becomes poor. Hemodialysis can buy time for kidney function to return, but if the kidneys are too damaged, euthanasia or a kidney transplant (a procedure with less than a 50% success rate in dogs) are the only remaining options.

Please help spread the word about grape and raisin toxicity in dogs. Ted’s family certainly wishes someone had mentioned the risk of these ubiquitous snacks pose before their beloved family member fell ill.

Dr. Jennifer Coates

Image: Thinkstock

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