Grapes and RaisinsBy now, most people (well, most educated dog-loving people) are aware of the relatively recent realization that grapes and raisins can be toxic to dogs. The big questions are "why" and "how much?"
I know you are all excited about the answers to those questions and the truth is, so am I! As soon as they figure it out I will let you know. But so far it seems we still don't have a definitive answer. So what do we know? So far fungus, pesticides, and heavy metals have been ruled out as the culprit. It also appears the toxicant is in the flesh of the fruit and not related to the seeds. For this reason we presume grape seed extract (whatever that is used for) to be safe.
So what about how much is toxic? The lowest recorded amount of grapes to cause acute renal failure is 0.7 oz per kilogram (about 9.5 ounces for a 30 lb dog). The lowest recorded amount for raisins is 0.11 oz per kilogram (about 1.5 ounces for the same 30 lb dog). However, smaller amounts may cause problems, we just don't know enough to be sure. To complicate matters more, not all dogs appear susceptible to this toxin-some can tolerate large amounts with no problems. Cats may be affected too but there is limited knowledge on this as most cats won't eat grapes or raisins.
Signs of grape or raisin toxicosis include vomiting, diarrhea, lethargy, anorexia, abdominal pain and decreased urine production.
Treatment includes induction of vomiting, administration of activated charcoal and symptomatic treatment along with fluid therapy and appropriate monitoring to combat the renal failure associated with severe intoxication.
If renal failure develops prognosis is guarded but with early and aggressive treatment many will recover.