Grape and Raisin Toxicity in Dogs

Grapes and raisins can cause kidney failure in dog and the number of identified cases of illness or death in dogs after they have eaten raisins or grapes is on the increase.

The type of raisins or grapes does not appear to matter, with reported cases of toxicity occurring after dogs have eaten seedless or seeded varieties, commercial or homegrown fruits, and grape pressings from wineries.

Since raisins are dried and therefore more concentrated than grapes, it appears that raisins are relatively more toxic than grapes. According to the Merck Veterinary Manual, the estimated toxic dose of grapes is 32 grams of grapes per kilogram of body weight (0.5 ounces per pound) and for raisins it is 11-30 g/kg (0.18 to 0.48 oz/lb).

Currently, it is not known why grapes and/or raisins are toxic. Some researchers suspect that a mycotoxin (a toxic substance produced by a fungus or mold) may be the cause. However, so far no toxic agent has been identified. Since it is currently unknown why these fruits are toxic, any exposure should be a cause for concern.

If you suspect that your pet has eaten any grapes or raisins, please contact your veterinarian immediately. Do not waste any time. Since there are still many unknowns associated with this toxicity, it is better not to take any chances when it comes to your pet's health.

The most common early symptom of grape or raisin toxicity is vomiting, usually within a couple of hours after ingestion. Next, the dog may develop diarrhea, excessive thirst, excessive urination or lethargy.

Acute kidney failure from a toxic dose of grapes or raisins will usually develop within 1-3 days. Symptoms of kidney failure include vomiting, diarrhea, dehydration, abdominal pain, and tremors or seizures. If the toxicity progresses, the kidneys will shut down and the dog will not produce any urine. The dog may develop foul breath (its breath will have the odor of urine) and in some cases ulcers may form on the gums at the locations where the salivary ducts drain. As the kidney failure progresses, the dog's blood pressure will elevate dramatically and the dog will usually lapse into a coma.

Unfortunately, the symptoms of grape or raisin toxicity are non-specific, and are similar to kidney failure from many other causes. Instead, your veterinarian will base a presumptive diagnosis of this toxicity based on a history of eating grapes or raisins, or the presence of pieces of grapes or raisins in the dog's vomit.   Your veterinarian will recommend diagnostic tests such as a Complete Blood Count (CBC), a Serum Biochemistry Profile and a urinalysis to assess the amount of damage to the kidneys, which will help determine what the dog's prognosis is for recovery. There is no antidote.

The goal of treatment is to block absorption of the toxins and prevent or minimize damage to the kidneys.

If treatment is started within 2 hours after the grapes or raisins were eaten, your veterinarian will induce vomiting to eliminate the fruits from the stomach, and will administer activated charcoal to block further absorption of the toxins. The patient will be put onto intravenous fluids to help flush any absorbed toxins out of the body as quickly as possible and to help maintain kidney function. Drugs to control nausea or vomiting and to help maintain blood flow to the kidneys will be administered as indicated.

During the course of treatment, your veterinarian will monitor the patient's kidney values to assess the response to treatment and determine whether the treatment needs to become more aggressive. Prognosis depends on many factors, including how many grapes or raisins were eaten, how ill the dog was when treatment was begun and whether the clinical signs improve once treatment is started. If the dog only ate a few grapes or raisins, and received immediate treatment, the prognosis is reasonably good. If the kidneys shut down so that no urine is produced, the prognosis is poor. It is important to realize that the kidneys have very little capacity to regenerate or repair themselves, and once the kidneys are damaged, they will not function as well as they did before the episode.

Your veterinarian will estimate the prognosis for your dog based on its clinical signs and individual situation. How can I prevent this problem?Keep all grapes and raisins, or foods containing grapes or raisins, out of reach of your dog. Do not share any food that may contain grapes or raisins with your dog, and especially do not use grapes as treats for your dog.

Onions, chocolate, cocoa, macadamia nuts, avocados and foods containing the sweetener xylitol can also be fatal.