Grape And Raisin Toxicity In Dogs

Veterinarians have known for some years now that certain dogs, upon eating small to large quantities of grapes and/or raisins succumb to reactions that vary from mild GI (gastrointestinal, stomach and intestine) signs to kidney failure to death. Cats, being fastidious eaters, probably just have better sense than to eat either raisins or grapes. Therefore, take no chances, and offer no grapes or raisins to your kitty.

The best collection of data on the subject comes from the ASPCA Animal Poison Control Center (APCC). Documentation of cases is sparse, because owners sometimes fail to realize that grapes and raisins are potential toxins, and may not think to mention the ingestion to the attending veterinarian.

The dogs who have the worst clinical signs have ingested large amounts of either raisins or grapes. Amounts ingested reportedly range from nine ounces to two pounds, yet there are anecdotes of dogs eating as little as one raisin or grape and succumbing mortally. If these reports are accurate, the natural inference is that some dogs are uniquely sensitive to the toxic ingredient, whatever it is. Larger dogs MAY tolerate larger amounts than small dogs, yet we recommend against feeding ANY raisins or grapes to your dog.

And, as of this writing, no one knows what the toxic ingredient is. Proposals include mycotoxins (poisons that certain fungi can manufacture), as well as pesticides and heavy metals that may be concentrated into grapes. No proof has been offered to be sure of the toxic agent.

Source and type of grape or raisin seems not to matter.

Interestingly, the first case reported in veterinary medical literature occurred in 1999. How did dogs survive eating grapes and raisins for thousands of years prior to that? Or, were there cases and no one made the connection? Is there something different about today’s grapes and raisins compared to yesteryears’? That, too, is still unknown.

What we do know is that the function of the dog’s kidneys is affected. A patient’s chances of survival depend on several factors:

  • total dose of raisins or grapes and/or individual sensitivity to the toxic factor(s).
  • quick evacuation of material through emetics (vomiting-inducing medications), colonics (enemas), and adsorption of toxins with activated charcoal.
  • quick support of kidney function with aggressive fluid therapy, with or without diuretics. Fluids and diuretics can also help to flush toxic products out of the kidneys before damage is widespread. Fluid therapy will be continued for a minimum of 48 hours and serum chemistry tracking for a minimum of 72 hours.
  • protection of the GI tract through medication.
  • the most severe cases may require weeks of treatment, costing thousands and thousands of dollars.
  • some kidney failure patients may require dialysis.

Vomiting may be the first evidence of toxicosis. If the vomiting is being caused by GI irritation, that’s good. If kidney damage is stimulating the vomiting because kidney damage is severe, the prognosis is extremely poor.

Affected dogs may have diarrhea, abdominal pain and lethargy. Regardless of the cause, grapes, raisins or otherwise, any of these signs are sufficient reason to at least call your pet’s doctor to let him decide whether your pet needs to be seen.

See you tomorrow, Dr. Randolph.


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