Clinical signs
Clinical signs exhibited by the dogs in cases reported to the ASPCA APCC have ranged from acute gastrointestinal signs (e.g. vomiting, anorexia) to acute renal failure (e.g. oliguria and anuria); death has also been reported. Vomiting occurs in all dogs and begins within the first few hours of
ingestion.4 Most affected dogs pass partially digested raisins or grapes in the vomitus, feces, or both. Within 24 hours, the clinical
signs observed in dogs include anorexia, lethargy, diarrhea, or abdominal pain.1 These gastrointestinal signs could last for days to weeks. A serum chemistry profile, especially blood urea nitrogen (BUN)
and creatinine concentrations, should be evaluated daily for at least three days after grape or raisin ingestion. If the results
are normal after three days, it is unlikely that renal failure will develop.2 However, even if the BUN and creatinine concentrations are normal, a serum chemistry profile should be repeated five to seven
days later. Abnormalities in BUN concentrations (23 to 209 mg/dl; normal = 5 to 29 mg/dl) and serum creatinine concentrations
(4.3 to 18 mg/dl; normal = 0.3 to 2 mg/dl) can become evident anywhere from 24 hours to several days after dogs ingest grapes
or raisins.1 Hypercalcemia (serum calcium concentration = 12.3 to 26 mg/dl; normal = 9.3 to 11.8 mg/dl) and hyperphosphatemia (serum phosphorus
concentration = 6.4 to 22 mg/dl; normal = 2.9 to 6.2 mg/dl) can also develop 24 hours to seven days after ingestion.1
As tubular damage progresses, dogs can become oliguric to anuric within 24 to 72 hours after ingesting large quantities of
grapes or raisins. Fatality in dogs with acute renal failure due to raisins has been reported to be as high as 50% to 75%.5 Concurrent oliguria or anuria in an affected dog is associated with a poor prognosis.6 In two reported cases, dogs that survived their oliguric renal failure showed no evidence of residual renal compromise several
months after the toxic insult.4
Treatment
Table 1: Emetics Used in Veterinary Medicine
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Because of the severity of the renal disease and potential for death, aggressively treat all dogs that have ingested grapes
or raisins. In dogs that have recently ingested large quantities of grapes or raisins, it is important to decontaminate the
gastrointestinal tract by administering emetics and activated charcoal. Emetics should be used only if the dog is stable,
is not having seizures, and is able to protect its airway (i.e. is not comatose and has normal laryngeal function). The various emetics used in veterinary medicine are listed in Table 1.8
Once emesis is induced, administer activated charcoal. Various preparations are available, including a dry powder, granules,
and a liquid suspension. Repeated administration of activated charcoal every four to six hours is beneficial in managing toxicoses
because it interrupts enterohepatic recycling. The dose of activated charcoal is 1 to 4 g/kg suspended in liquid.8 It is best administered through a stomach tube.8
Maintaining renal perfusion is extremely important in preventing the progressive decline in glomerular filtration rate and
onset of renal failure. Hospitalize asymptomatic dogs, and give them a balanced electrolyte solution intravenously at a maintenance
rate for at least 48 hours. Closely monitor the dog's renal function, including BUN and creatinine concentrations and urine
output, over 72 hours after grape or raisin ingestion. Dogs with anuric or oliguric renal failure should receive aggressive
fluid therapy to help restore renal perfusion and electrolyte and acid base balance. Diuresis may also be beneficial in reducing
the amount of time the renal tubules are exposed to the toxic principle.4
Summary
Until information on the pathophysiology and specific treatment of grape and raisin toxicosis becomes available, it is best
to contact the ASPCA APCC (888-426-4435) when a case arises. The ASPCA APCC has specially trained staff who provide assistance
to pet owners and specific diagnostic and treatment recommendations to veterinarians. Because affected dogs could die, instruct
owners to stop feeding their dogs grapes, raisins, and any food containing grape extracts. If ingestion should occur, advise
owners to seek veterinary assistance immediately to initiate aggressive medical management. For more information on the toxicity
of grapes or raisins, see the ASPCA APCC Web site (
http://www.apcc.aspca.org/).
Brandy Porterpan, DVM
Department of Small Animal Clinical Sciences
College of Veterinary Medicine
Texas A&M University
College Station, Texas 77843
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