Last Updated on April 3, 2023 by Becky Roberts
How many of us pet parents know that grapes can cause kidney failure in dogs?
Well, I didn’t, until a few years ago. I nearly fed some granola mix with raisins to my ever-curious dog (gasp!). Fortunately, my best friend Alex (who’s nerdier than I am) was right there to stop me. Otherwise, my baby would’ve ended up at the hospital. (Yikes.)
So, yes, the danger is real. But how many grapes or raisins does it take for these to be a real danger to our beloved fur babies? Can a single grape kill a dog?
- 1 Dose versus size
- 2 How dangerous grapes can be
- 3 Renal failure
- 4 Why grapes are dangerous
- 5 What you can do
- 6 Summary
Dose versus size
Not quite. It all depends on the size of the dog.
Most dog breeds are bigger than, say, a pint of beer — so it’s unlikely that one little grape can kill most dogs. However, if we’re talking about a tiny dog or puppy, one grape could still be enough to send the poor thing to the hospital.
How dangerous grapes can be
Don’t believe grapes can be this toxic? Just ask Wendy Donaldson about it.
Back in 2017, Wendy and her young son were watching TV while eating fresh red grapes. Their energetic little 5 month-old dog Leah (a Pomeranian-Pekingese mix) was in the room with them.
Wendy was so engrossed in the show onscreen that she failed to notice how her son, Matthew, had placed the container with grapes within easy reach of the puppy. Leah took a few sniffs and began eating the fruits. Wendy only noticed what was happening after the pup had already swallowed about 10 grapes.
Wendy wasn’t alarmed; at the time, she didn’t know about grapes being toxic to dogs. But she wanted to keep the fruits exclusively for herself and her son, and so (fortunately!) she took the grapes away.
The next day, Leah was lethargic. She began vomiting and having diarrhea.
Alarmed, Wendy began searching for answers on the Internet — and discovered that grapes are poisonous for dogs. She then rushed Leah to the ASPCA Animal Hospital in Manhattan, New York for treatment.
After a physical exam and blood tests, the vet at the ASPCA hospital diagnosed exactly what the grapes had done to poor Leah: acute renal failure. This meant the dog’s kidneys were beginning to fail.
To save Leah’s life, the vet decided to treat her with gastro protectants, while keeping her stable with intravenous fluids. It worked. A week later, Leah was well enough to go back home to the Donaldsons.
The Donaldsons’ experience is similar to other earlier documented cases of grape poisoning. One particular case from 2004, unfortunately, ended in tragedy.
Sara Wright of Wisconsin lost her beloved pet Penny (a St. Bernard-Australian Shepherd mix) after the dog ate about a cup of raisins. (And raisins are, of course, the dried version of grapes.) At two years of age, Penny was a much larger and older dog than Wendy’s little fur ball Leah. Yet that cup of raisins was enough to affect Penny’s system. She began vomiting so badly that her owner Sara had to take her to the hospital. A few days later, the dog developed acute renal failure that eventually became the cause of her death.
Why grapes are dangerous
But what’s making grapes harmful to dogs?
Sadly, we don’t yet know. The phenomenon has gained recognition only in the last 10-15 years, so veterinary research has yet to catch up and zero in on the exact cause. No one is sure if it’s something that’s inherent to grapes or if it’s something that gets added to grapes in large-scale commercial production (e.g., trace chemicals left behind by pesticides, food preservatives).
So far, there are two theories.
Theory #1: It’s a mycotoxin.
Some researchers suspect it’s a mycotoxin produced a fungus or mold present in grape skins.
This isn’t a surprising theory. Many other fungi or molds naturally find their way to fruit skins, including those of grapes. These include a few species of Penicillin fungi which produce tremorgenic mycotoxins known to affect dogs’ nervous systems, causing convulsions, vomiting, tremors, loss of coordination, and abnormally high heart rates. It’s not a great stretch of the imagination, then, to think there could be another mycotoxin present that causes kidney injury in dogs.
Theory #2: It’s a salicylate.
Meanwhile, other scientists think a naturally-occurring salicylate or salicylic acid-based compound is the culprit.
Salicylic acid is the active ingredient in aspirin, which we humans use to treat pain, fevers, and inflammation. But it also helps slow blood flow, especially in dogs. It could ultimately lead to decreased blood flow to the kidneys.
And this is all that science can tell us…for now.
What you can do
So what’s a doggie parent to do? Here are a few tips on keeping your dog safe.
Tip #1. Keep fresh grapes, raisins, currants, and sultanas away from your dog.
When we say grapes are poisonous to dogs, we don’t mean just the fresh grapes. We’re talking about the dried versions as well — raisins, currants, and sultanas.
And it won’t matter if grapes or its dried versions are mixed into cereals or baked into snacks or desserts. If your dog gets to eat enough of the fruits — even a single grape — it could be enough to harm him. So make sure your dog gets only the safest dog food or treats.
Note: Grape juice appears to be safe, however. Similarly, grape seed extract is supposed to be safe. But this has yet to be proven.
Tip #2. Know the symptoms of grape poisoning.
But — sigh! — some dogs still find their way into trouble, don’t they? In case that happens, it’s useful for you to remember these symptoms of grape toxicity, which occur within 24 hours after eating grapes:
- nausea and vomiting
- lethargy and lack of appetite
- abdominal pain
- excessive peeing
- excessive thirst
- bad breath (smelling of urine)
Tip #3. Bring your dog to the vet.
If your dog shows signs of grape toxicity, consider it a medical emergency. The best step in first aid is simple — bring him to the vet hospital, right away.
Don’t even wait for another day, when the symptoms are followed by something far worse, like a drop in blood pressure and your dog going unconscious. By then it might be too late. Successful treatment for acute kidney failure means early treatment. Once your dog’s kidneys go beyond saving, there won’t be anything you or the vet can do to save your dog’s life.
Tip #4. Have activated charcoal and hydrogen peroxide on hand for emergencies.
But what if you can’t bring your poisoned dog to the hospital right away?
If you get to your dog right after he’s swallowed grapes, giving your dog a dose of 3% hydrogen peroxide and activated charcoal may be used to induce vomiting. This can be another useful first aid step to prevent the full absorption of the toxin through the stomach or intestines.
However, be sure to first phone your vet to get his or her guidance on using this method on your dog.
In short, keep your dog as far from grapes, raisins, sultanas, or currants as possible. Grapes compromise a dog’s kidney functions. Grape poisoning is a serious health risk for your dog, and a few fruits might be enough to make a toxic dose!