Boxers can safely enjoy most fruits, but grapes are one to avoid.
While some owners report feeding grapes with no adverse effects, grapes have a history of causing acute renal failure and death in dogs.
Exactly how grapes poison dogs remains unknown, even in 2021.
Grapes that tested free of pesticides and free of mold have caused problems … and both seedless and seeded varieties are implicated.
Raisins, currants and sultanas are all made from dried grapes and are also toxic to dogs.
This post is for general informational and educational purposes only. I encourage readers to see my full disclaimer here.
Are Grapes Safe For Boxer Dogs?
The available evidence suggests grapes are not safe for your Boxer, or any other dog.
According to the ASPCA Animal Poison Control Center, sensitive dogs have a risk of initial gastrointestinal upset followed by acute renal failure.
They call it “grape or raisin toxicosis” or GRT.
Why Do Grapes Cause Problems For Dogs?
This is a mystery.
The exact mechanism of grape and raisin toxicosis is unknown.
- metabolic disruption
- nephrotoxic mycotoxins on grapes (toxins produced by molds)
- contamination of grapes with heavy metals or pesticides
- excess vitamin D
- tannin intolerance
- excessive ingestion of monosaccharides
- hypovolemic shock (low blood volume)
- renal ischemia (inadequate blood supply to the kidneys)
What’s strange is that some wolves do eat grapes.
Dogs Naturally Magazine reported that zoologist and wolf researcher Dr Isla Fishburn told the 2016 Raw Roundup conference that individual wolves had been observed eating grapes as part of their diet.
Grape toxicosis in pet dogs was unheard of until the 1980s.
This timing would support the theory that it’s related to pesticides.
Are Pesticides To Blame For Grape Toxicity In Dogs?
In an interview in 2016, the FBI analyst Melissa Gardner told integrative veterinarian Dr Karen Becker that wine from Californian grapes contained high amounts of fluoride, from the fluoride-based pesticide cryolite.
Cryolite has been in use since the eighties, which is exactly when vets first noticed raisin toxicity in dogs.
According to United States Department of Agriculture data, grapes are the sixth most pesticide-laden fruit.
(Strawberries were the most contaminated, followed by spinach, kale, nectarines and apples.)
In some cases, grapes that have caused acute renal failure in dogs have been tested for pesticides, heavy metals and mycotoxins .. and found to be negative for all three substances.
What if the pesticide itself was not detectable, but some of its base ingredients, like fluoride, were present in amounts large enough to be toxic?
More research is required.
Which Part Of The Grape Is Toxic?
It’s not known whether the skin of the grape is the problem, or the flesh.
What Kinds Of Grapes Cause Problems For Dogs?
Grapes in a wide variety forms have been associated with acute renal failure in dogs, including:
- grapes from a grocery store
- grapes found in the backyard
- grape pressings from wineries
- grape skins, seeds and stems used as natural fertilizer
- both seedless and seeded varieties
Are All Grape-Related Products Dangerous?
Dried grapes of all kinds are just as risky as grapes.
Never give your Boxer:
In fact, these products are even more likely to cause problems because the drying process concentrates nutrients.
Grapeseed oil or extract (made from the seeds of grapes) does not appear to be a threat.
(Grape seed oil is not recommended for other reasons, namely that it’s high in omega-6 fatty acids, which will further skew a modern dog diet already high in omega-6s compared to omega-3s.)
What Is A Toxic Dose Of Grapes?
No one knows how many grapes a Boxer has to consume to get sick or die.
Some dogs have severe reactions after just a few grapes, whereas others consume a whole bunch and are fine.
The lowest documented grape dose to cause acute kidney injury is:
- 0.31 ounces per pound of dog weight (19.6g/kg) for grapes, and
- 0.04 ounces per pound (2.8g/kg) for raisins.
The ASPCA Animal Poison Control Center recommends that all grape or raisin ingestion be considered potentially serious.
The good news is grapes seem to digest slowly.
Whole grapes have been found in a dog’s stomach the morning after the day they were consumed.
This means if you act fast, you have time to save a dog that’s accidentally eaten grapes.
Symptoms Of Grape Or Raisin Toxicosis
The most likely sign of grape toxicity that you’ll see in the first 2 hours is vomiting.
81 per cent of dogs vomit within 24 to 48 hours of eating grapes.
Symptoms that typically occur within the first 5 to 6 hours include:
- loss of appetite
- great thirst
- oliguria (excreting only tiny amounts of urine)
Acute renal failure involves:
- abdominal pain
- hypovolemia (decreased blood volume)
Less common symptoms include:
- severe neurological symptoms (more than 75 per cent of dogs in one recent European study)
- ataxia or loss of coordination (in 23 per cent of dogs)
- peeing a lot
Some studies suggest problems can arise as long as several days after consuming grapes.
But if your Boxer is going to suffer an adverse reaction to grapes, you will usually know it much sooner than that.
Symptoms of grape toxicosis typically appear after 6 hours and almost always within 24 hours.
Blood tests may show abnormally high levels of:
This is called uremia, the presence in the blood of urea and other nitrogenous waste compounds normally excreted by the kidneys.
The condition may worsen to encompass:
- kidney necrosis (tissue death)
- tubular degeneration
- kidney mineralization
How Is Grape Toxicosis Diagnosed?
Diagnosis of GRT hinges on:
- history of exposure to grapes or raisins
- evidence of acute renal failure
A recent study out of Switzerland suggests the presence of neurological symptoms can make initial diagnosis of grape toxicity more difficult.
Swiss researchers found neurological disturbance can occur early in the onset of grape toxicity, even before bloodwork shows abnormalities.
These findings suggest that if a dog has severe gastrointestinal disturbance alongside neurological symptoms and may have had access to grapes, grape toxicosis should be considered.
It’s possible that the impaired kidney function causes the neurological symptoms.
An acquired toxic syndrome known as “uremic encephalopathy” is well-described in human medicine.
Inadequately treated end-stage renal patients develop confusion and can end up having seizures and lapsing into a coma.
Any diagnosis of GRT should first rule out other causes of acute renal failure such as:
- ethylene glycol poisoning (the chemical in antifreeze)
- other underlying disease
How Do You Treat Grape Poisoning In Boxer Dogs?
If your Boxer has consumed grapes, you want him to vomit to expel the grapes.
How To Make Your Boxer Vomit After Eating Grapes
Veterinarian Dr Karen Becker advises owners to induce vomiting within 30 minutes of grape ingestion.
She says to give your dog 3 per cent hydrogen peroxide at a dosage of just less than 1mL per pound of body weight (2 mL per kg) … but give no more than 45mL in total.
You can administer hydrogen peroxide by squirting it into the back of the mouth with a (needle-less) syringe or turkey baster.
Your dog should throw up within 15 minutes.
Vomiting can work as long as no more than 2 hours has passed since your dog ate the grapes.
Activated charcoal can be given afterwards, to absorb remaining toxins.
What Will Happen At The Vet
Fluid diuresis (increased fluid intake to induce maximum peeing) for the first 48 hours may help prevent acute renal failure developing.
Blood chemistry should be monitored for 72 hours, including renal enzymes.
When the dog has gone into anuric (not producing urine) renal failure, vets may resort to drugs like:
Other procedures may be used to purify the blood, including:
- periotoneal dialysis
What Is The Prognosis If A Boxer Develops Grape Toxicosis?
Studies suggest slightly more than half of dogs that suffer acute kidney injury as a result of eating grapes will survive.
In one study of 43 dogs with grape-induced renal failure:
- 12 per cent died, and
- 35 per cent were euthanized for failure to respond to treatment.
Dogs that make it through the initial emergency seem to recover almost complete renal function long term.
The likelihood of survival depends on:
- whether the dog vomits and expels the grapes
- how early the dog receives treatment
If the dog stops urinating (becomes anuric), the prognosis is said to be poor.
Neurological symptoms are apparently reversible, but generally take several days (as long as several weeks) to improve.
How To Prevent Your Boxer Eating Grapes
Rather than in the fruit bowl, store grapes in the fridge where your Boxer can’t reach them — even by counter surfing.
Take care when unpacking groceries or eating grapes yourself.
Be sure to pick up any grapes that are dropped, before they can roll under benches and be forgotten .. to be discovered by your dog later.
Good Fruit For Boxer Dogs
Safe fruits to feed your Boxer include:
Melons like papaya, cantaloupe and honeydew are all suitable for dogs and have the added benefit of being among the fruits least likely to be contaminated with pesticide residues, according to the most recent USDA data.
Grapes, raisins, currants and sultanas are known to cause kidney failure in dogs.
Dogs have died after eating them.
It’s true that some dogs appear to be able to consume grapes with no ill effects.
But with so many other entirely safe and delicious fruits to choose from, why take the risk?
Toxicosis with grapes or raisins causing acute kidney injury and neurological signs in dogs, Ariane Schweighauser et al, published in Journal of Veterinary Internal Medicine, Volume 34, Issue 5, 7 September 2020