By Dr. Karen Shaw Becker
Grapes are one of the top fruits produced and consumed around the world. According to the University of Missouri, countless nations annually produce a total of 72 million tons of this fruit, with late August being the optimal time for harvesting.1
Grapes are so deeply ingrained in history that in fact, there’s a whole field of study dedicated to it: viticulture.2 One of the earliest pieces of evidence of grape cultivation is a 9,000-year-old wine residue (with a combination of rice and honey) found in pottery shards located in a village in central China. In Iran, acidic deposits from 7,400-year-old grape jars have been recovered.3
Alongside humanity’s love for grapes is their love for dogs. Ever since these friendly animals were domesticated, people have been feeding their pets scraps of various foods, including grapes.4 In recent years, however, you may have heard that these grapes can be toxic for dogs. Yet, there’s evidence that it doesn’t cause problems as well. So which side of the fence should you pick?
Can Dogs Have Grapes?
The American Society for the Prevention of Cruelty to Animals (ASPCA), acknowledges that grapes can be toxic for dogs, but the exact mechanics are still unknown.5 What’s interesting however, is that this phenomenon only gained prominence a few decades ago. Before, grape toxicity in pets was unheard of.
In 2016, I interviewed Melissa Gardner, an intelligence specialist working for the Federal Bureau of Investigation (FBI). She is also a former intelligence officer for the military and a Fulbright scholar to the United Kingdom (U.K.).
In our conversation, Gardner outlines a plausible theory that may explain why in the past few years, grapes started becoming unsafe for dogs and for pets in general. She discovered that wine from California grapes is laced with high amounts of fluoride due to cryolite, a fluoride-based pesticide that also contain other elements such as sodium and aluminum.
Cryolite spraying began in the 1980s when the Environmental Protection Agency (EPA) approved its use. Incidentally, 1989 was the year when veterinarians began to notice the trend of raisin toxicity in dogs, and it is the same timeframe when Europeans detected high amounts of fluoride from wine imported from California.
Based on Gardner’s findings, studies need to be funded to ascertain these claims. For the meantime, she suggests that pet parents test the fluoride levels in dogs who developed raisin toxicity. Results from urine and blood samples can tell if your pet ingested a large amount of fluoride so that proper treatment can be taken.
What Happens if a Dog Eats Grapes?
For humans, consuming grapes can reap health benefits, such as:
- Cardiovascular health protection — The polyphenols found in grapes, such as resveratrol, possess antioxidant properties that may help promote heart health thanks to its lipid-lowering and anti-inflammatory properties.6,7
- Reduced Type 2 diabetes risk — A report from The BMJ notes that consumption of whole fruits such as8 grapes, blueberries and apples had a lower risk of developing Type 2 diabetes.9,10
- Better eye health — A mice study suggests that the resveratrol found in grapes may help promote eye health by positively affecting various biological pathways such as oxidative stress, inflammation and mitochondrial dysfunction.11
In dogs, two things may occur when they eat grapes — either nothing happens, or they may develop alarming symptoms, especially when consumed in large amounts. One study found that the most fatal cases of grape poisoning occurs when the ingested amount is 10 to 57 grams per kilogram of body weight.11 If your dog accidentally eats a single grape, they can go about their day as if nothing happened. But if you noticed that they ate a whole bunch of grapes, be on the lookout for the following:12
|Vomiting or diarrhea (often a few hours after eating)
||Loss of appetite
||Lethargy, weakness or unusual quietness
|Oliguria (excreting only a small amount of urine)
||Anuria (complete stop of urine)
Another thing you should watch out for is kidney failure, which can be fatal to your pet. Several studies have pointed out that an unknown toxin in grapes and raisins is responsible for inducing renal failure.13,14,15,16
Note that all symptoms typically appear after six hours, and always within 24 hours.17 More studies will need to be done to ascertain what specifics in grapes can cause digestive problems, as other factors may contribute to the problem. For example, dogs who developed renal failure have been discovered to have grapes in their stomach, but a host of other foods as well. In my own practice, I’ve given dogs grape seed extract with great results, which means that certain compounds in grapes can benefit your pet’s health.
My Dog Ate Plenty of Grapes — What Should I Do?
Researchers have found that there’s ample time for treatment, as they note that whole grapes have been recovered after remaining overnight in a dog’s stomach.18 Still, if you notice that your dog accidentally ate a large amount of grapes, immediate action must be taken to prevent a fatality from occurring, as you can never be too sure of what might happen to your dog if you put if off for too long. Here’s what to do:
- Call your veterinarian for immediate advice and intervention.
- If you can’t bring your dog to the veterinarian right away, you may induce vomiting by administering 3 percent hydrogen peroxide (2 milliliters per kilogram of body weight, but no more than 45 milliliters) followed by activated charcoal.19
- To administer hydrogen peroxide, you may use a syringe (without a needle) and squirt the liquid into the back of the dog’s mouth. A turkey baster can also work in this situation.20
- After your pet has vomited, bring them dog to the veterinarian for aggressive intravenous fluid (IV) therapy, which is required for two days to properly rehydrate and repair the kidneys, along with monitoring.
- If vomiting at home is unsuccessful, your veterinarian will administer a gastric lavage to remove the grapes right away and proceed to step 4.21
While inducing vomiting may help, PetMD notes that this method should not be attempted if your dog is:22
- Having trouble breathing
- Showing signs of distress or shock
If you’re unsure of what your pet may have eaten, do not induce vomiting as well.
Can Cats Eat Grapes?
Interestingly, cats are less susceptible to eating grapes, as researchers believe that due to their more discriminating habits and appetites, they rank lower in reported consumption of toxic foods. However, that doesn’t mean they’re out of the woods.
While there’s very little information regarding grape toxicity in cats, what is known is that they’re more likely to consume chocolate and onions, which can cause health problems, such as hemolytic anemia,23 a condition wherein the red blood cells are destroyed before their regular lifespan is over.24
Store Your Food Properly to Prevent Pet Problems
Given how clever dogs and cats can be, they’re going to grab a bite from your food sooner or later. To prevent health problems and save yourself from emotional stress, store your food properly out of your pet’s reach, or invest in containers that they won’t be able to open. The occasional grape may not be bad for them, but don’t overdo it either. Always keep your pet’s health in mind, first and foremost.
Frequently Asked Questions About Feeding Grapes to Dogs
Q: Are grapes bad for dogs?
A: Yes, grapes can be bad for dogs as this fruit can cause a variety of complications, such as kidney failure. The exact reason for this occurrence is unknown, but it is important that you do not feed your dog grapes.25 On the other hand, some dogs may be unaffected by grape consumption.
Q: Can grapes kill dogs?
A: Yes. In a study published in the Journal of Veterinary Medicine that evaluated renal failure in 43 dogs due to grape consumption, 12 percent died while 35 percent had to be euthanized due to failure to respond to treatment.26
Q: My dog ate one grape. Will he be OK?
A: Grapes are slowly digested, which can give you enough time to seek help. In one study, grapes have been found in a dog’s stomach overnight. Going to a vet and inducing vomiting can increase your pet’s chances of survival.27