Reprinted from VETgirl blog.
Grapes and raisins (Vitis spp.) have been recently associated with development of acute kidney injury (AKI) with ingestion. All types have been implemented with toxicosis, including organic grapes, commercial grapes, homegrown grapes, and seedless or seeded grapes. Common kitchen items also contain grapes, raisins, or currants in their active ingredient, including raisin bread, trail mix, chocolate-covered raisins, cereal with raisins, etc. Currently, grapeseed extract has not been associated with nephrotoxicity.1 While the mechanism of how grapes and raisins cause AKI is unknown, there are several suspected hypotheses, including individual inability to metabolize certain components of the fruit (e.g., tannins, high monosaccharide content),1 the presence of mycotoxins or pesticide residues on the fruit,1 or salicylate-like chemicals within the grape or raisin.
While older publications2 report a toxic dose of grapes and raisins (e.g., grapes: 0.7 oz/kg; raisins 0.11 oz/kg), VetGirl suspects it is idiosyncratic and not necessarily dose-dependent... and hence, we treat any significant ingestion (e.g., more than a few). While 1-2 grapes or raisins is unlikely to result in an toxicity issue, more significant amounts should be decontaminated and treated. The majority of ingestions should be treated as potentially idiosyncratic and should be appropriately decontaminated and treated.
Clinical signs of grape and raisin toxicity include:
Additional treatment includes aggressive intravenous fluid therapy, anti-emetics, blood pressure and urine output monitoring, and serial blood work monitoring (q. 12-24 hours). In severe cases, hemodialysis or peritoneal dialysis may be necessary. Asymptomatic patients that have been adequately decontaminated and survive to discharge should have a renal function and electrolytes monitored 24-48 hours post-ingestion.
When in doubt, ASPCA Animal Poison Control Center can be consulted for life-threatening emergencies or azotemic, oliguric patients. Referral for a 24/7 specialty clinic is warranted for oliguric or anuric patients. Overall, the prognosis is fair to good, depending on time to decontamination, response to therapy, and prevalence of oliguria or anuria. Overall, 50% of dogs that ingest grapes and raisins never develop clinical signs or azotemia. As with any toxicant, the sooner a toxicity is identified (e.g., prior to clinical signs developing), the sooner it can be decontaminated and treated for a better prognosis.
1. Craft E, Lee JA. Grapes and raisins. In: Osweiler G, Lee JA, et al. Blackwell’s Five-Minute Veterinary Consult Clinical Companion: Small Animal Toxicology, 1st Ed. Iowa City: Wiley-Blackwell, 2010. pp. 429-435.
2. Eubig PA, Brady MC, Gwaltney-Brant SM, et al. Acute renal failure in dogs after the ingestion of grapes or raisins: a retrospective evaluation of 43 dogs (1992-2002). J Vet Int Med 2005;19(5):663-674.
Dr. Tania Woerner, owner and sole veterinarian at Tally Oaks Veterinary Wellness Center in Purcellville VA.