Overview

Grapes, raisins, and related fruits, including sultanas and Zante currants, can cause sudden life-threatening kidney failure in dogs. The amount of fruit ingested needed to cause harm varies, so any ingestion should be treated as an emergency.

If your dog eats grapes, raisins, or any related fruits, contact your veterinarian or a pet poison control center immediately. Prompt veterinary care can be life-saving and greatly improves the chance of preventing or limiting kidney damage.

Cause

The exact cause of grape and raisin toxicity is not fully understood, but research suggests that tartaric acid and its salt, potassium bitartrate, are the most likely cause. These substances are found in high concentrations in grapes, raisins, sultanas, Zante currants, tamarinds, and cream of tartar. Tartaric acid levels vary from fruit to fruit, and dogs differ in their sensitivity, so the amount that causes harm is unknown and cannot be predicted. For this reason, any ingestion should be treated as potentially toxic.

Clinical Signs

While some dogs do not show clinical signs early on, signs will often appear within 6-24 hours after ingestion and may include:

• Vomiting (most common)
• Diarrhea
• Loss of appetite
• Dehydration
• Abdominal distention or pain
• Excessive drooling
• Lethargy

Signs may progress over 1-3 days and include:

• Increased thirst and urination
• Weakness or incoordination
• Swelling of the limbs (edema)
• Trembling, tremors, or seizures
• Inability to urinate (anuric kidney failure)

Diagnosis

A diagnosis may be based on a history of a known or suspected ingestion of grapes or related products, or if parts of fruit are noted in a dog’s vomit. Fruit may remain visible in vomit up to 12 hours after ingestion. 

Your veterinarian may recommend blood and urine tests to evaluate kidney function and other abnormalities associated with grape ingestion. 

Since blood levels may be normal within the first few hours after ingestion, repeat testing may be recommended over two to three days.

Treatment

There is no specific antidote for grape or raisin toxicity. Treatment focuses on removing any remaining fruit to prevent further absorption of toxin (decontamination) and supportive care. 

For recent ingestion with no clinical signs of illness, your veterinarian will induce vomiting. Even if several hours have passed, this may still be effective because the fruit can linger in the stomach.

Supportive care involves hospitalization for IV (intravenous) fluid therapy and close monitoring for at least two days. Monitoring will include frequent rechecks of kidney values, electrolytes, urine output and blood pressure. Additional treatments may include medications to prevent nausea and protect the stomach.

In severe cases that do not respond to treatment or worsen, hemodialysis (a process that filters waste from the blood) may be considered for dogs that develop anuric renal failure. However, this treatment is usually only available at certain specialty or university veterinary hospitals.

Outcome

Dogs that are treated promptly and never develop kidney damage generally have an excellent prognosis. For dogs that do develop kidney damage, the outlook is serious, and many do not survive. In severe cases, the kidneys may stop producing urine, and the risk of death is high even with treatment. Dogs that survive kidney injury may also develop long-term kidney problems. 

Prevention

• Never feed grapes, raisins, sultanas, Zante currants, or foods containing them to dogs.
• Store food securely out of reach of dogs.
• Secure trash bins or compost from dogs accessing them.
• Remove grape vines in areas where dogs have access.