Everyone knows that chocolate is bad for your pets. But many people aren’t aware that grapes and raisins can cause major problems for dogs (and maybe cats). Really, it is a fruit. How bad can it be?
Eating grapes and/or raisins has been shown to cause acute (sudden) kidney failure in dogs (and some cats). No one knows why this happens, but fungal, pesticide, and heavy-metal causes have pretty much been eliminated. Recent unpublished data indicates that the toxic component is water-soluble, and within the flesh of the grape/raisin, not the seed. So grapeseed extract may be safe to use. It isn’t known if pasteurization makes the compound non-toxic, so it isn’t recommended to give your dog grape juice.
Unlike chocolate, which affects all dogs depending on the amount eaten, not all dogs have problems eating grapes. But since we don’t know which dogs are susceptible, it makes the most sense to not feed your dog grapes or raisins at all. Amounts that have caused clinical signs have varied from 0.18 to 0.5 oz/lb in one study. For perspective, an ounce of grapes can be about 10 small grapes or 3 large grapes!
The lowest recorded amount that caused acute kidney failure was 0.32 oz/lb for grapes and 0.05 oz/lb for raisins. For a 25 pound dog, that is about 8 ounces of grapes or a little over 1 ounce of raisins.
After eating the grapes/raisins, a dog may show clinical signs several hours later. Vomiting and lethargy are generally seen first, then the signs of kidney failure–increased drinking, increased (or absent) urination, inappetance, and diarrhea are seen within 24 hours. Partially digested grapes and raisins might be seen in the vomit, fecal material, or both. There have been cases of gastrointestinal signs continuing for several weeks post ingestion.
If your dog ate a bunch of grapes or raisins, getting him to vomit soon after is the best idea. Your veterinarian can guide you in the best way to do this. If that isn’t effective or if your dog ate the grapes/raisins several hours before you noticed, then a visit to the vet would be worthwhile. Your vet will likely do blood testing and check a urine specific gravity (concentration of the urine) to see if the kidneys are working normally. Early and aggressive fluid treatment may be needed, as the prognosis is guarded once renal failure develops.
The best treats for dogs? Vegetables (except for onions and garlic)!