Raisins and Grapes

The exact mechanism of toxicity is unknown, although the primary injury appears to be in the proximal renal tubular epithelium. Affected dogs develop anuric renal failure within 72 hr of ingestion of grapes or raisins. A clear dose-response relationship has not been determined, but as few as 4–5 grapes were implicated in the death of an 18-lb (8.2-kg) dog.

Most affected dogs develop vomiting and/or diarrhea within 6–12 hr of ingestion of grapes or raisins. Other signs include lethargy, anorexia, abdominal pain, weakness, dehydration, polydipsia, and tremors (shivering). Serum creatinine levels tend to rise early and disproportionately compared with serum urea nitrogen levels. Oliguric or anuric renal failure develops within 24–72 hr of exposure; once anuric renal failure develops, most dogs die or are euthanized. Transient increases in serum glucose, liver enzymes, pancreatic enzymes, serum calcium, or serum phosphorus develop in some dogs.

Diagnosis is based on history of exposure, along with clinical signs. Other causes of renal failure (eg, ethylene glycol, cholecalciferol) should be considered in the differential diagnosis.

Prompt decontamination of significant ingestion of grapes or raisins is recommended. Emesis may be induced with 3% hydrogen peroxide (2 mL/kg; no more than 45 mL), followed by activated charcoal. With large ingestions or in cases in which vomiting and/or diarrhea has spontaneously developed within 12 hr of ingestion of grapes or raisins, aggressive fluid diuresis for a minimum of 48 hr is recommended. Renal function and fluid balance should be monitored during fluid administration. For oliguric dogs, urine production may be stimulated by using dopamine (0.5–3 mcg/kg/min, IV) and/or furosemide (2 mg/kg, IV). Anuric dogs are unlikely to survive unless peritoneal dialysis or hemodialysis is performed; even then, the prognosis is guarded.