A recent letter in JAVMA has suggested that tartaric acid is the cause of acute kidney injury in dogs (Wegenast C. Meadows I, Anderson R, Southard T. JAVMA. 2021;258(1):706-707). The evidence provided includes cases of renal failure in dogs that have eaten cream of tartar (potassium bitartrate); one dog had renal histopathology similar to that seen in dogs with grape toxicosis. Studies have shown that dogs have high rapid renal excretion of tartaric acid and its salts, compared to other species. Tamarinds, which are also high in tartaric acid, have caused acute renal failure in dogs.

Commercial wine and grape juice are detartrated (excess tartrates are removed) to protect flavour and appearance and are therefore not associated with toxicosis in dogs.

The amount of tartaric acid and potassium bitartrate in grapes varies by type of grape, environmental growing conditions and growth stage but there is sufficient to cause kidney injury in dogs. This variation in tartaric acid concentrations emphasises the lack of toxic dose for grape/raisin ingestion. More research is needed to confirm these suspicions.