New Research Sheds Light on the Mystery as to why Grapes and Raisins are so Bad for Dogs

We have known for many years that grapes, raisins and sultanas can be very harmful to some dogs, causing vomiting, diarrhoea, excessive thirst and in severe cases kidney failure but the reason why has remained a mystery. 

In recent weeks a team of Vets have managed to shed some light on this and It is now thought to be the tartaric acid (and its salt potassium bitartrate) in grapes and raisins which causes these symptoms. What has always been puzzling is that some dogs only suffer mild symptoms like an upset stomach while others suffer severe effects such as kidney failure. 

This could be explained by the fact that grapes, raisins and sultanas contain different levels of tartaric acid since levels relate to the type of grape, where it was grown and the level of ripeness and this may explain why not all dogs are affected. The discovery was made by a Vet who was treating a dog who had eaten playdough. 

Usually in such cases dogs will develop dangerously high levels of sodium in the blood but in this particular case the high levels did not develop.  The Vet asked for the recipe of the home-made play dough and found that it differed from usual recipes in that it contained cream of tartar, which also contains tartaric acid.  Dogs are known to be sensitive to tartaric acid and the Vet noted similar symptoms to those who had suffered raisin and grape toxicosis (acute vomiting and kidney failure).

They also noted that the Animal Poison Control Centre had reports of severe vomiting and acute kidney failure in dogs following exposures to tamarinds which are also uniquely high in tartaric acid. These findings have recently been published as a letter to the editor of the latest issue of the American Veterinary Medical Association.

The authors propose that tartaric acid and its salt, potassium bitartrate  are the toxic principles in grapes leading to acute kidney failure in dogs. So it is worth checking ingredients for anything containing cream of tartar as it has been seen in some homemade dog treats