Grape and raisin toxicity in dogs

Grape and raisin toxicity in the dog is a potential health threat to dogs that have eaten grapes or raisins. It can cause the dog to develop acute renal failure (the sudden development of kidney failure) with anuria (a lack of urine production). The phenomenon was first identified by the Animal Poison Control Center (APCC), run by the American Society for the Prevention of Cruelty to Animals (ASPCA). A trend was seen as far back as 1999.^[1] Approximately 140 cases were seen by the APCC in the one year from April 2003 to April 2004, with 50 developing symptoms and seven dying.^[2]

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Cause and pathology

The reason why some dogs develop renal failure following ingestion of grapes and raisins is not known. Types of grapes involved include both seedless and seeded, store bought and homegrown, and grape pressings from wineries.^[3] A mycotoxin is suspected to be involved, but one has not been found in grapes or raisins ingested by affected dogs.^[4] The estimated toxic dose of grapes is 32 g/kg (grams of grapes per kilograms of mass of the dog), and for raisins it is 11–30 g/kg.^[5] The most common pathological finding is proximal renal tubular necrosis.^[6] In some cases, an accumulation of an unidentified golden-brown pigment was found within renal epithelial cells.^[7]

Symptoms and diagnosis

Vomiting and diarrhea are often the first symptoms of grape or raisin toxicity. They often develop within a few hours of ingestion. Pieces of grapes or raisins may be present in the vomitus or stool. Further symptoms include weakness, not eating, increased drinking, and abdominal pain. Acute renal failure develops within 48 hours of ingestion.^[4] A blood test may reveal increases in blood urea nitrogen (BUN), creatinine, phosphorus, and calcium.

Treatment

Emesis (induction of vomiting) is the generally recommended treatment if a dog has eaten grapes or raisins within the past two hours. A veterinarian may use an emetic such as hydrogen peroxide or apomorphine to cause the dog to vomit. Further treatment may involve the use of activated charcoal to absorb remaining toxins in the gastrointestinal tract and intravenous fluid therapy in the first 48 hours following ingestion to induce diuresis and help to prevent acute renal failure.^[1] Vomiting is treated with antiemetics and the stomach is protected from uremic gastritis (damage to the stomach from increased BUN) with H₂ receptor antagonists. BUN, creatinine, calcium, phosphorus, sodium, and potassium levels are closely monitored. Dialysis of the blood (hemodialysis) and peritoneal dialysis can be used to support the kidneys if anuria develops. Oliguria (decreased urine production) can be treated with dopamine or furosemide to stimulate urine production.^[5]

The prognosis is guarded in any dog developing symptoms of toxicosis. A negative prognosis has been associated with oliguria or anuria, weakness, difficulty walking, and severe hypercalcemia (increased blood calcium levels).^[6]

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