Although many dog owners and dog trainers have traditionally used raisins and grapes as treats, RAISINS AND GRAPES IN LARGE QUANTITIES CAN BE LETHAL TO DOGS. As few as a handful of raisins or grapes can make a dog ill; however, of the ten cases reported to the ASPCA Animal Poison Control Center (APCC), each dog ingested between nine ounces and two pounds of grapes or raisins
If your dog has ingested large quantities of raisins or grapes, (s)he will immediately begin to vomit repeatedly, and will become extremely hyperactive and jittery. After about 24 hours, the dog will become lethargic and depressed. (S)he may experience abdominal pain and may stop urinating, drinking, and/or eating. (S)he will also become dehydrated. Both his/her vomit and feces will contain partially digested raisins or grapes. His/her breathing may become irregular, and (s)he will also become hypercalcemic (high calcium concentrations) and hyperphosphosphatemic
Ultimately, without treatment, the dog will go into renal (kidney) failure, and may die a horrible very painful death. Of the ten reported cases, only five dogs survived, and these only with early, aggressive, and long-term treatment
The best cure for an overdose, of course, is prevention. Because dogs can get hold of raisins or grapes from a variety of sources—the kitchen counter, the coffee table, vines in a private vineyard, a child’s lunch box—DOG-PROOF YOUR VINEYARDS and REMOVE RAISINS AND GRAPES FROM CANINE REACH. Do not feed your dog raisins/grapes as treats so that you can avoid him/her “getting a taste for them.” Remember that raisins are even more concentrated (and hence more toxic) than grapes—approximately four pounds of grapes equal one pound of raisins. The APCC also warns that any substance in large doses can be toxic.
However, if you suspect your dog has eaten a large amount of raisins or grapes, take your dog to a veterinarian immediately, and have them contact the Animal Poison Control Center for assistance. Have your veterinarian initiate decontamination measures, and administer fluids and/or dialysis to assist/restart the dog’s kidneys. Be aware that initially your veterinarian may suspect rat poison as the above symptoms are very similar to the symptoms of rat poison.
The APCC is still unable to determine the cause of renal (kidney) failure. Possibilities include 1) an agent in grapes and raisins themselves; 2) fungicides, herbicides, or pesticides contamination; 3) heavy metals; 4) high amounts of Vitamin D; or 5) fungus or mold contamination.
Information on raisin and grape toxicity is still very new; therefore, your veterinarian and fellow dog owners may not yet be aware of the danger. Please pass on this information to every dog owner, veterinarian, rescue group, breeder, newsletter, listserve, and pet food store you can.