Common Toxicities Series – Grapes and raisins

Most dog owners are aware that grapes and raisins are toxic to dogs.  However, this knowledge is relatively new, and both grapes and raisins were commonly used as treats in dog training until about 10 years ago.  How is it that we didn’t know about this toxicity earlier?  As it turns out, not every dog will have issues with ingesting grapes and raisins, and the risk of toxicity appears to be genetically determined.  Some dogs can eat large amounts of grapes and have no consequences.  However, because we cannot tell which dogs are susceptible to grape toxicity, and there is no genetic test available to determine this, we recommend treating every grape or raisin ingestion seriously.  In addition, although we usually discuss grape toxicity in dogs, there are anecdotal reports of cats also having the same susceptibility, so the following information applies to both species.
In susceptible cats and dogs, grapes and raisins cause acute kidney failure.  The specific toxic substance in grapes/raisins has not been identified but it is believed to be within the flesh of the grape, rather than the seed, so grapeseed extract is thought to be safe.  It is unknown whether grape juice can be toxic.  The lowest recorded toxic doses in dogs are approximately 0.3 oz/lb of grapes and 0.05 oz/lb of raisins.  
If your dog (or cat) ingests grapes or raisins of any quantity, our goal is to minimize the risk of kidney failure.  If the ingestion was very recent, the first course of action is to induce vomiting to bring up as much of the undigested material as possible.  Then we administer activated charcoal in order to absorb as much of the toxin as possible before it has a chance to be absorbed by the body.  If the ingestion was not very recent, then these two steps may not be skipped.  The next step is to diurese the body with intravenous fluids in order to encourage faster removal of the toxin from the bloodstream.  The fluids should be continued until at least 48 hours post-ingestion.  Bloodwork to assess kidney function is recommended at the start of treatment, at the 48-hour mark post-ingestion, and at 72 hours post-ingestion.  If the kidney values are still normal at the time, then it is highly unlikely that the pet will develop kidney failure.
If left untreated, signs of problems generally develop within several hours of ingestion.  Initial signs are usually vomiting and lethargy.  Within approximately 24 hours, the kidneys are damaged to the point that they will either stop making urine or will make very small amounts of urine.  Once urine production is affected, the prognosis for recovery becomes very guarded, even with aggressive treatment.  For this reason, early treatment is recommended in every case of grape and raisin ingestion.  Please call us immediately if you ever have cause to believe your dog or cat has ingested grapes or raisins in any quantity.
Next in the Common Toxicities Series: Xylitol
Roscoe Village Animal Hospital’s veterinarians serves the medical and dental needs of animals in Chicago’s Lakeview, Lincoln Park, North Center, Wicker Park, Uptown , West Loop, Logan Square and Bucktown neighborhoods.