Grape/Raisin/Currant (Tartaric Acid) Toxicity

Ingestion of grapes or raisins (Vitis spp), Zante currants (aka corinth raisins) and tamarinds (Tamarindus spp) can cause gastrointestinal upset and kidney failure, including death in some dogs.

Why are Grapes, Raisins and Tamarinds Toxic in Dogs?

The proposed toxic principle in these fruits is tartaric acid. Tartaric acid, an organic acid, is present in variably high concentrations in these fruits.  Dogs poorly excrete organic acids because they lack the organic acid transporters that other species have, allowing the tartaric acid to accumulate in their kidney cells causing damage.

Affected dogs develop oliguric or anuric renal failure, meaning they lose the ability to produce urine, generally within 72 hours of ingesting these fruits. This can be fatal. 

The tartaric acid content of grapes, raisins, and tamarinds varies, resulting in variable effects following ingestion. In general, more than one grape or raisin per 4.5 kg (10 pounds) of body weight may contain enough tartaric acid to pose a risk for renal effects in dogs. Since there is variability in the amount of Tartaric acid, some fruits grow have very little and so an ingestion may have no negative affect; while another will have much more and cause toxicity.  However, since a very small amount can cause severe illness and death, any ingestion should be treated seriously. 

Symptoms & Clinical Findings of Grape, Raisin and Tamarind Toxicity in Dogs

Most dogs with grape, raisin, or tamarind toxicosis develop vomiting or diarrhea within 6 to12 hours after ingestion. Other symptoms include lethargy, anorexia, abdominal pain, weakness, dehydration, excessive drinking, and tremors (shivering).

Within 24 to 72 hours after ingestion, partial or complete failure to produce urine, called oliguric or anuric renal failure, will occur. Once complete anuric renal failure occurs most dogs are euthanized or die. 

Blood tests can show increasing kidney enzyme levels of creatinine and then in blood urea nitrogen. Occasionally in some dogs other blood changes occur such as increases in: blood sugar, liver enzymes, pancreatic enzymes, calcium, and phosphorus levels.

Diagnosis of Grape, Raisin and Tamarind Toxicosis in Dogs

Diagnosing grape/raisin toxicity is usually based on a history of ingestion or exposure to these fruits. Our veterinarians will also do a clinical evaluation often including blood and urine tests.  There are other toxins that can cause similar signs and kidney failure including ethylene glycol (anti-freeze) and cholecalciferol (vitamin D).

Treatment of Grape, Raisin and Tamarind Toxicosis in Dogs

The primary treatment of this toxicity is first through gastrointestinal decontamination when possible and then with intravenous fluid therapy. Close and careful monitoring of kidney function through blood tests is needed. 

Gastrointestinal decontamination means removing as much ingested fruit as possible, meaning our veterinarians will make the dog vomit.  This will only typically be done in the first several hours after ingestion, and only if the veterinarian has assessed that the dog can be safely made to vomit.  Oral activated charcoal is sometimes used to reduce how much toxin is absorbed, but it is unknown if activated charcoal is effective against tartaric acid. 

Intravenous fluids are essential for any dog that has eaten a large amount of the fruit, or has started developing clinical signs. IV fluids are recommended for at least 48-72 hours, with close monitoring of blood and urine parameters, and fluid balance during this time. 

If the kidneys start to fail (oliguric renal failure), there are a few medications that can be tried. However if the kidneys fail completely (anuric renal failure), the prognosis is extremely poor and dogs at this stage are unlikely to survive. 

We recommend treating all grape, raisin and tamarind ingestions as an emergency, as early veterinary care can be life saving.