Based on recent data, the ASPCA Animal Poison Control Center (APCC) continues to caution canine caretakers that raisins and grapes may be toxic to some dogs. From April 2003 to April 2004, the Center managed 140 related cases, each involving one or more dogs who ingested varying amounts of raisins or grapes.

Take the case of two-year-old Penny, Sarah Wright’s Australian shepherd/Saint Bernard mix. Earlier this year, Penny ate approximately a cup of raisins. "She vomited later that same day," recalls Sarah. "I took her in to be evaluated by our local veterinarian, who felt that she was simply experiencing stomach upset, as the clinic was not aware of the potential for toxicity with raisin ingestion." But a few days later, when Penny didn’t improve, the veterinarian ran blood tests and found that she had developed acute renal failure. Despite efforts to save Penny, she passed away. "I want to share this unfortunate loss, so that other dog owners can be educated and avoid having their dogs go through what Penny did," Sarah says.

Much is yet to be discovered about the toxic principle in grapes and raisins. It is also not clear if only some canines are susceptible, or if chronic, long-term ingestion can lead to the same effects. "As there are still many unknowns," says the APCC’s Dana Farbman, CVT, "we advise not giving grapes or raisins to pets in any amount."