The Wrath of Grapes
by Charlotte Means, D.V.M.


Magoo was a big, playful Labrador retriever who often got himself into
some sticky situations. Usually, his escapades were harmless. But one day, he
managed to snag a box of raisins from the pantry and ended up eating an
entire pound of the sweet treats. Other than being exasperated by Magoo's
behavior, his guardians didn't think much about it. They knew that lots of
people shared grapes with their dogs and often used raisins as training
rewards. So it hardly seemed the kind of emergency that required a call to
the veterinarian. In fact, if Magoo's parents had called the ASPCA's Animal
Poison Control Center (APCC) just a few years ago, they would have been
told not to worry about it.

Through the Grapevine

Enter the APCC AnToxTM database, a computerized system that
contains nearly 500,000 animal-related medical conditions and that enables
veterinarians to quickly identify toxic-substance exposures, recognize
clinical signs and administer proper treatment. By tracking cases in this
registry, similarities in animal medical conditions nationwide can be logged
and syndromes can be identified.

Around 1989, the APCC began noticing a trend in dogs who had eaten grapes
or raisins: Nearly all developed acute renal (kidney) failure. As more cases
were reported, enough data was generated in the database to help
veterinarians identify and treat dogs at risk. In all of the cases, the
ingredients for potential acute renal failure were the same. Whether the
ingested grapes were purchased fresh from grocery stores or grown in private
yards didn't seem to matter, nor did the brand eaten. And the ingested
amounts varied considerably, from over a pound of grapes to as little as a
single serving of raisins. The cases weren't from any specific region, but
instead came from across the United States.

The database showed that dogs who ate the grapes and raisins typically
vomited within a few hours of ingestion. Most of the time, partially
digested grapes and raisins could be seen in the vomit, fecal material, or
both. At this point, some dogs would stop eating (anorexia), and develop
diarrhea. The dogs often became quiet and lethargic, and showed signs of
abdominal pain. These clinical signs lasted for several days -- sometimes
even weeks.

When medical care was sought, blood chemistry panels showed consistent
patterns. Hypercalcemia (elevated blood calcium levels) was frequently
present, as well as elevated levels of blood urea nitrogen, creatinine
and phosphorous (substances that reflect kidney function). These chemistries
began to increase anywhere from 24 hours to several days after the dogs
ate the fruit. As the kidney damage developed, the dogs would produce little
urine. When they could no longer produce urine, death occurred. In some
cases, dogs who received timely veterinary care still had to be
euthanized.

Why did the fruit cause the dogs to become ill? No one knows. Suspect
grapes and raisins have been screened for various pesticides, heavy metals
(such as zinc or lead), and mycotoxins (fungal contaminants) and so far, all
results have come back negative. In the cases where the grapes were grown in
private yards, owners confirmed that no insecticides, fertilizers or antifungals
had been used on the fruit.

"Raisin" the Success Rate

Even though the exact cause of the renal failure is unknown, dogs who
ingest grapes and raisins can be treated successfully to prevent its
development.  The first line of defense is decontamination. Inducing vomiting
in recent ingestions and administering activated charcoal helps prevent absorption of  potential toxins. Dogs should be hospitalized and placed on intravenous  fluids for a minimum of 48 hours. A veterinarian should monitor blood  chemistry daily for at least three days following the ingestion. If all  blood work is normal after three days, it's unlikely that kidney failure  will occur. If a dog shows evidence of renal failure, fluids must be  continued, and other medications should be used to stimulate urine
production. Some dogs may need peritoneal dialysis, a process where the
peritoneum (the membranes surrounding the abdominal organs) is used to
filter waste products that are normally filtered by the kidney.

Thanks in part to the AnTox database, grape or raisin ingestion can be
easily identified and treated. Today, a dog can make a complete recovery
from this potentially fatal condition.

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