Toxic Component in Grapes and Raisins Identified!

For years, we’ve known grapes and raisins were poisonous to dogs—but we weren’t sure of the toxic agent. As published in the Journal of Veterinary Emergency and Critical Care, kidney damage has been seen in canines after exposure to cream of tartar and tamarinds. During the necropsies, renal lesions, which resembled those appreciated in post-mortem assessments on dog kidneys exposed to grapes and raisins, were discovered. This helped connect the dots on tartaric acid as being the cause of the kidney issues in grapes, raisins, tamarinds, and cream of tartar.

Because the clinical signs, laboratory findings, and histopathologic lesions were like those reported in grape and raisin toxicosis, toxicologists were able to surmise that the harmful agent in all the poisonings was tartaric acid. 

This new information will help pet owners and veterinarians alike: 

• Pet owners can be more cautious when using products containing tartaric acid, including homemade playdough and tamarind paste. 

• Veterinarians and toxicologists will be more prepared to treat pets exposed to tartaric acid in all its forms. 

Study Design  

The authors connected a case in which a dog developed acute kidney injury after ingesting homemade playdough with cream of tartar to grape poisoning in dogs. Cream of tartar is a form of tartaric acid and is found in notably high concentrations in grapes and tamarinds. Previous studies have demonstrated dogs’ sensitivity to the nephrotoxic effects of tartaric acid. The case series describes cases from the ASPCA Animal Poison Control Center database in which dogs developed acute kidney injury following exposures to cream of tartar or tamarinds and compares clinical signs and diagnostic findings to grape toxicosis.  

Study Results 

Ingestion of cream of tartar or tamarind may lead to vomiting and acute kidney injury in dogs.  The clinical signs, laboratory findings, and histopathologic lesions are consistent with what have been reported in grape and raisin toxicosis. Tartaric acid, a nephrotoxin in dogs, is the common denominator and the likely toxic component.  

Key Study Takeaways 

Twenty years after the first cases of kidney injury from grape and raisin ingestions were described, the study has identified the likely toxic component.  The concentration of tartaric acid in grapes varies from 0.35% to 2%, which makes predicting toxicity difficult.  Similar to grape and raisin exposures, decontamination and intravenous fluid diuresis should be considered following significant ingestions of cream of tartar and tamarind.    

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