Dogs and Raisins: A Toxic Mix, by Deborah Flick at www.boulderdog.net
The following is an exert from the article:
I had an informative chat with the ASPCA toxicologist about raisins and grapes. Here's what I learned:
1. Dogs and raisins/grapes have been around a long time but it's only been in the last 15 years or so that we've recognized that the fruit is a kidney toxin to dogs.
2. Organic raisins/grapes apparently are no less toxic than non-organic ones.
3. We don't know what it is in raisins/grapes that make them toxic to dogs.
4. A toxic reaction, kidney failure, might not be dose dependent. "We can't say with certainty that fewer raisins/grapes are less toxic than lots of them. It appears to be idiosyncratic. Maybe some dogs are genetically predisposed to being unable to tolerate even one raisin/grape. We just don't know."
5. That said, the lowest toxic dose reported so far is about 3 grams (.11 oz.) of raisins per 1 kilogram (2.2 pounds) of dog weight, or about 20 grams (.7 oz.) of grapes per 1 kilogram of dog weight.
The picture above is what 3 grams of raisins looks like.
The bottom line is this: Please protect your dog from getting into raisins and grapes.