Letters 02/02: A Grape Mystery
A poison control center database search reveals poisoning danger.
Have you heard anything about grapes and raisins being toxic to dogs? I read on one of the dog lists that a dog died after eating a box of raisins. I give grapes as treats and use organic raisins as training treats. Should I discontinue this practice?
Contrary to rumors sent to us by several readers, grapes and raisins haven’t suddenly gained toxicity. A review of poisoning cases in the database kept by the ASPCA Animal Poison Control Center in Urbana, Illinois, revealed the grape/raisin overdose danger.
In all, researchers found 21 cases where a dog had become sick following the ingestion of a large amount of either grapes or raisins. The poisonings occurred in a 12-year period, from 1989 through April 2001. The authors of the study are now conducting an even more thorough database search of poisoning cases, and according to one of the authors, have found “numerous” additional cases where an overdose of grapes or raisins may be implicated in a poisoning case; further study is ongoing.
The 21 incidents described so far were very serious; 20 of the 21 dogs developed evidence of renal dysfunction; 3 dogs died, and 4 were euthanized due to poor response to treatment. Initially, most of the dogs vomited; more than half had diarrhea, and about a third displayed a lack of appetite, lethargy, and/or abdominal pain. Researchers are trying to determine what was responsible for the acute renal failure: mycotoxins, pesticides, heavy metals, or a toxin that has yet to be determined.
Unfortunately, the amount of grapes or raisins that were ingested could be estimated in only 12 of the 21 cases. One case involved a dog who ate about 2 pounds of red seedless grapes. The raisin eaters consumed 8 to 16 ounces in one sitting. The smallest dosage seen in the cases equaled 1 ounce of fruit per 2.2 pounds of the dog’s body weight (10 ounces of fruit eaten by a 22-pound dog, for example). A variety of fruit was implicated: fresh grapes came from both grocery stores and vines on private property; one dog ate fermented grapes from a winery. The raisins were commercial raisins of various brands. The ASPCA Animal Poison Control Center provides telephone assistance to veterinarians and animal guardians 24 hours a day, 7 days a week. The Center charges a flat fee of $45 for a phone consultation, which includes as many follow-up calls as necessary. To consult the APCC, call (888) 426-4435.
We would hesitate to call for a complete ban on feeding grapes or raisins based on these reports. However, we suggest exerting absolute control over your dog’s access to these foods – don’t leave grapes or raisins anywhere a dog might be able to reach them – and limiting his total intake of both foods. And, of course, if your dog eats a large amount of either food, OR displays any sign of illness after eating any amount of these foods, take him to your vet ASAP.
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