Can Dogs Eat Grapes? The Truth About Toxicity

Dog owners commonly ask, “Can dogs eat grapes or raisins?” After all, grapes and raisins seem like healthy snacks. Why would something so nourishing be toxic for pets?
Unfortunately, reports in recent years have proven that the ingestion of grapes and raisins can be toxic for dogs.

According to the American Society for the Prevention of Cruelty to Animals (ASPCA), over 200 calls were made to the Animal Poison Control Center (APCC) between January 2001 and August 2004 involving potential exposure to grapes or raisins. In the year between April 2003 to April 2004, 50 dogs developed symptoms and seven died.

Any grape, raisin, or currant can cause acute kidney failure in dogs. There is no difference between seeded and seedless grapes, or organic or conventionally grown. Products that contain these ingredients include trail mix, grape juice, snack and protein bars, raisin bread, raisin bran cereal, rice pudding, various types of cookies (like oatmeal raisin), raison extract, wine, as well as many other products.

What Causes Grape and Raisin Toxicity in Dogs?

Despite testing, the reason for the kidney (renal) failure and the amount necessary for toxicity remain unknown. Some believe a mycotoxin may be involved, but this has not been documented. While some dogs are able to eat grapes without a problem, others can die from a very small amount.

The quantity of grapes or raisins ingested that have resulted in toxicity is typically between a few ounces and 2 pounds. Studies conducted by the ASPCA Animal Poison Control Center suggest that the lowest documented toxic raisin dose is 0.1 oz per kilogram of body weight and 10 to 12 grapes in a 20-pound dog. Raisins are 4.5 times or more concentrated than grapes on an ounce per ounce basis. Some species of currants can be toxic, such as the Vitis sp., while others, like the Ribes sp, are nontoxic.

It appears all breeds of dogs are susceptible to toxicity with no predisposition to age or sex. There is no way to know which dogs will be affected. All cases of grape or raisin ingestion should be considered potentially serious. Any dog that ingests a large amount of grapes or raisins should be treated aggressively, so contact your veterinarian as soon as possible if ingestion has occurred. Prolonged treatment may be necessary to give the affected dog a chance at survival. Without treatment, death is a serious possibility.

What Are Symptoms of Raisin and Grape Toxicity?

Symptoms of toxicity include lethargy, increased thirst, and diarrhea, progressing to more severe signs that include lack of appetite, vomiting, increased urination, dehydration, tremors, weakness, abdominal pain, trouble walking, decreased urine output, and progressive depression. Most dogs experience symptoms within 6 to 12 hours of ingestion, presenting as vomiting, anorexia, and lethargy. Once symptoms begin, they can progress over 24 to 48 hours. Most dogs that are affected go into renal failure within 72 hours.

The type of kidney damage that occurs is renal tubular necrosis, which is found through histopathologic testing. While necrosis (death of the tissue) occurs, the basement membrane appears intact, which allows for possible recovery.

Diagnosis is based on the dog’s history and evidence of grapes or raisins in vomit or a bowel movement, clinical signs, and blood tests that show elevated kidney values (blood urea nitrogen (BUN) and creatinine) and abnormal electrolytes like calcium and phosphorus. A urinalysis may show urine that is not concentrating normally, with abnormal amounts of glucose, protein, and/or casts. Abdominal radiographs and ultrasound testing are generally unremarkable.

How Do You Treat Toxicity?

Treatment varies depending on the recency of ingestion and clinical signs.

Options include:

• Induction of vomiting, with drugs such as apomorphine or oral 3% hydrogen peroxide, is recommended If ingestion of grapes or raisins was within a few hours. Vomiting may be recommended up to 12 hours post ingestion.
• Activated charcoal, which is a form of carbon that works to “absorb” various substances, including toxins, in the gastrointestinal tract. It is given orally every 8 hours for 24 hours.
• Intravenous (IV) fluid therapy, which is recommended for 48 to 72 hours to correct dehydration and stimulate urine production to prevent failure of the kidneys.
• Symptomatic care, which may include medications to prevent vomiting (such as Maropitant or Metoclopramide) and stomach protectants.
• Drugs to stimulate urine production, such as Mannitol or Furosemide.
• Dialysis, which can be used to support kidney damage.
• Evaluation of blood work at least once daily. A recheck of blood work is generally recommended one-week post exposure.

What Is the Prognosis for Recovery from Grape and Raisin Toxicity?

The prognosis of grape and raisin toxicosis depends on the individual dog. Some dogs have no problems or symptoms, while others go into sudden kidney failure.

The best prognosis is associated with early diagnosis and treatment. Decontamination procedures, such as inducing vomiting to remove the grapes or raisins from the stomach and activated charcoal, can prevent absorption.

In dogs with signs of acute kidney failure, the prognosis is guarded. Decreased urine production, difficulty walking, weakness, high blood calcium levels (hypercalcemia), and/or progressive elevation of kidney values are associated with a poor prognosis.

Prevention Tips

The best way to prevent toxicity is to avoid exposure.

Make sure all grapes and raisins are out of reach of your dog. If you have a picnic or party with guests, inform them of any dishes that contain grapes or raisins and provide instructions not to give them to your dog. Some pet owners toss old shriveled or dried grapes in the trash or compost pile, which may provide access to dogs. Properly dispose of trash in a covered trash can.