In 2016, the nationwide Poison Control Center hotline operated by the American Society for Prevention to Cruelty to Animals received 4,068 calls from pet owners whose dogs had ingested grapes or raisins, which was a 39 percent jump from the 2,934 calls in 2015, according to Tina Wismer, medical director of the society.
Widmer said the connection was formed in the past 15 years after a cluster of calls received by veterinarians in which dogs had ingested grapes or raisins and went into kidney failure.
Symptoms some dogs show after eating grapes or raisins can include vomiting, diarrhea, lethargy, lack of appetite and difficulty urinating, according to a 2002 "Animal Watch" report from the society.
"That prompted our hotline veterinarian to check our database and discover several other cases with dogs that had eaten grapes and raisins and had gone into kidney failure. That revelation kick-started the research looking into the link between grapes/raisins and kidney failure in dogs," Wismer said.
Wismer said as more people find out about grapes/raisins being potentially life threatening to their dogs, the number of calls have increased. But as of now, it is unclear why some dogs are impacted and not others.
"We don’t know if it is something in the grapes themselves or if it has some genetic basis and only certain animals are susceptible," Wismer said.
In the past week, a few bites of a raisin bagel sent a pup to the emergency room at MedVet, an animal hospital at 3123 N. Clybourn Ave. in Roscoe Village, according to a technician, while another dog — a 14-pound terrier mix owned by a DNAinfo reporter — was hospitalized for three nights and four days at MedVet after eating a red seedless grape. The bill for the four-day trip was $2,395.
Jerry Klein, a veterinarian at MedVet, said on average MedVet sees two to five cases of grape ingestion per week. And the prognosis is generally good if veterinary intervention is early, he added.
Klein said that since the exact cause of the toxicity is unknown, there is no way to determine how many grapes it will take to cause an impact to a dog.
"That will vary since each grape is a different size and weight, but the main point is that even a single grape can cause kidney failure. We have seen dogs who were affected after eating only one grape, while others can eat several grapes and not be affected," Klein said.
Klein said if a dog does eat a grape, the first step is making the dog vomit if the grape or grapes were ingested recently.
If vomiting does not work, MedVet recommends IV fluid administration, typically for two days, to minimize the chance of the kidneys being affected.
Klein said grapes and raisins cause "an idiosyncratic toxicity," which means that not every dog is susceptible.
"Many dogs can tolerate large quantities without problems, while others can be affected by a single grape. It is unknown what the patient risk factors are other than ingestion. ... Unfortunately we do not know what the minimum toxic dose is, so it is recommended that all dogs be treated aggressively, as if the ingestion may result in acute renal disease," Klein said.
The society recommends performing blood work to obtain baseline kidney values and hospitalizing for 2-3 days with IV fluid therapy to flush and absorbed toxins from the system, Klein said.
Klein said it "tends to be the mischievous types of dogs who get into the trash or steal food off the counter who are most likely to be affected."
"We have heard stories of dogs who steal grapes from grocery bags before the owner has a chance to put them away, or young kids who share grapes with the dog or drop them on the floor. We've also had owners who intentionally offer their dogs grapes/raisins as a treat without realizing they can be toxic," Klein said.
Wismer said the society knows of one death last year due to raisin ingestion but deaths from grape or raisin ingestion are difficult to track because there is no national tracking agency.
Klein said that MedVet typically does not see fatalities associated with grape ingestion, but there have been instances in which pets who experience kidney failure and become anuric — a condition in which the extent of kidney damage is so severe that dogs are unable to produce urine — are humanely euthanized due to the long recovery and poor prognosis.
"This only occurs in extreme cases of severe renal failure and is uncommon," Klein said.
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