Why Raisins & Grapes Are Toxic To Dogs: Our Vet Explains

Why Raisins & Grapes Are Toxic To Dogs: A Vet Explains
What may seem like a sweet, healthy snack for us can spell disaster for our dogs. As a veterinarian, one of the most dangerous food toxicities I see in my canine patients is from grapes and raisins. These fruits can cause rapid kidney failure and even death in dogs, and prompt treatment is crucial. In this article, I‘ll explain why grapes and raisins are so hazardous to dogs, share what to watch for, and discuss what to do if your pup is exposed.

What Makes Grapes & Raisins Toxic to Dogs?
The exact toxic substance in grapes and raisins remains a mystery, but we do know that ingesting even small amounts can make dogs very sick. The type or source of the grapes or raisins doesn‘t seem to matter – whether they‘re fresh or processed, homegrown or store-bought, or from red or green grapes, they all pose a danger.

A few leading theories propose these potential culprits:

  1. Fungal mycotoxins – Grapes and raisins could contain toxic compounds produced by mold or fungus growth on the fruit.
  2. Salicylates – Grapes contain salicylic acid, which is similar to aspirin. Aspirin and other NSAIDs can damage the kidneys in high doses.
  3. Tartaric acid – Some believe the tartaric acid in grapes is what harms the kidneys, as this acid has been linked to kidney problems in humans.

However, these are still just working theories. The bottom line is that both grapes and raisins are toxic to dogs, regardless of the amount. There‘s no safe dose that‘s been established.

How Are Dogs Exposed to Grapes & Raisins?
Dogs find many creative ways to get their paws on grapes and raisins. Exposure often occurs when:

  • Stealing grapes off backyard vines
  • Snatching them from bowls on counters or tables
  • Accepting them as treats from well-meaning owners
  • Scavenging raisins from the ground
  • Sharing trail mix, cereal, or baked goods that contain them
  • Getting into boxes of raisins or bags of grapes

Raisins are also especially easy for dogs to vacuum up because of their small size and wrinkled texture. Both grapes and raisins are popular in many households, so exposure opportunities are widespread.

Are Grapes or Raisins More Toxic?
Raisins tend to be more concentrated than fresh whole grapes, so it takes a smaller amount to cause poisoning. For example, 1/3 ounce of raisins can be toxic to an 18 lb dog, while it takes about 2.5 ounces of grapes to cause problems for the same size dog.

However, all dogs have different sensitivities. The lowest reported toxic doses are around 0.05 oz of grapes per lb of body weight and 0.003 oz of raisins per lb. But some dogs have gotten very sick from much smaller amounts. No amount has been proven reliably safe for all dogs.

Signs of Raisin & Grape Toxicity in Dogs
The most common early sign of toxicity is vomiting, usually within 24 hours of ingestion. You might see partially digested grapes or raisins in their vomit. Not all dogs will vomit, but it‘s often one of the first red flags.

Other gastrointestinal (GI) signs may include:

  • Diarrhea
  • Abdominal pain
  • Excessive drooling
  • Inappetence (not wanting to eat)
  • Lethargy

These GI signs can then progress to symptoms of acute kidney injury within 1-3 days:

  • Markedly increased thirst and urination
  • Dehydration
  • Very bad breath (uremic odor)
  • Oral ulcers
  • Tremors
  • Abnormal heart rhythms
  • High blood pressure
  • Lack of urine production

If enough damage occurs, the kidneys may fail altogether. This leads to a buildup of toxins in the bloodstream, causing seizures, coma, and death. Needless to say, this is a very dangerous toxicity that warrants immediate treatment.

What To Do If Your Dog Eats Raisins or Grapes
Rapid response is crucial. If you suspect or know that your dog ingested any grapes or raisins, call your veterinarian, emergency animal hospital, or pet poison control hotline right away. They can advise you on the appropriate steps to take based on your dog‘s size and how much they ate.

As a very rough guideline, here are some estimates of a toxic dose:

  • 10 to 12 grapes for a 10 lb dog
  • 20 to 25 grapes for a 20 lb dog
  • 30 to 40 grapes for a 30 lb dog
  • 10 to 15 raisins for a 10 lb dog
  • 20 to 25 raisins for a 20 lb dog
  • 30 to 40 raisins for a 30 lb dog

Even if your dog only ate a few grapes or raisins, it‘s still best to contact a vet or poison control expert to be safe, especially if you have a small dog. And if it has been less than 2 hours since they ingested the fruit, your vet may advise inducing vomiting at home with hydrogen peroxide.

Diagnosis of Raisin & Grape Toxicity
Diagnosis relies heavily on witnessing or suspecting grape/raisin ingestion, as there is no definitive test for this toxicity. Your vet will also perform a thorough physical exam and likely run some lab work, including:

  • Chemistry panel and complete blood count (CBC) to check kidney function, electrolytes, and hydration
  • Urinalysis to evaluate the concentration and quality of your dog‘s urine
  • Blood pressure measurement

These diagnostics provide a baseline to monitor from and help rule out other potential causes of your dog‘s symptoms. Partially digested grapes or raisins in your dog‘s vomit or stool can also be a key indicator of exposure.

Treatment for Raisin & Grape Toxicity
The goal of treatment is to quickly eliminate any remaining grapes/raisins from your dog‘s system and aggressively support their kidneys to stave off failure. This usually requires hospitalization for 2-3 days (or more), and may include:

  • Inducing vomiting – If ingestion was recent and your dog isn‘t already vomiting, your vet will give an injection to purge their stomach contents.

  • Gastric lavage – Flushing out the stomach under anesthesia to remove as much of the toxic fruit as possible.

  • Activated charcoal – Administering activated charcoal helps bind any remaining toxins in the GI tract to limit further absorption.

  • IV fluid therapy – Providing intravenous fluids is critical to flush out the kidneys, keep your dog hydrated, and maintain their electrolyte balance. The fluids are dosed based on your dog‘s kidney values and monitored ins and outs.

  • Anti-vomiting medication – Drugs like maropitant or ondansetron help control nausea and vomiting so your dog can keep down the charcoal and maintain hydration.

  • Kidney function monitoring – Your vet will regularly check your dog‘s kidney values, urine output, and blood pressure to assess the extent of any damage.

  • Symptomatic care – Additional treatments like antacids, phosphorus binders, calcitriol, or even dialysis may be needed if kidney failure occurs.

Sadly, even dogs who receive prompt treatment can still suffer fatal kidney damage. It often depends on how many grapes/raisins they ate, how long their kidneys were exposed to the toxins, and their individual susceptibility.

Prognosis for Dogs Who Ingest Grapes or Raisins
The prognosis is always guarded in these cases due to how unpredictable grape/raisin toxicity can be. Some estimates suggest up to 50% of dogs who ingest grapes/raisins will develop kidney failure, and up to 3% may die despite treatment.

However, the outlook is best for dogs who:

  1. Ate only a small number of grapes/raisins relative to their body weight
  2. Receive treatment within 2 hours of ingestion, before symptoms begin
  3. Respond quickly to IV fluids and supportive care
  4. Have no signs of kidney damage on initial bloodwork

Dogs who already have impaired kidney function are at even higher risk for serious complications. If your dog develops kidney failure from grape/raisin toxicity, recovery can take weeks to months. Some dogs will have permanent kidney damage and require a specialized renal diet and medications for life.

How to Prevent Raisin & Grape Toxicity
Awareness and vigilance are key to preventing this dangerous toxicity. Here are some tips:

  • Securely store grapes, raisins, and any foods/mixes containing them well out of your dog‘s reach.
  • Avoid using grapes/raisins as treats, and never leave them unattended.
  • Teach your dog a solid "Leave It" command in case they encounter fallen fruit.
  • Consider crate training, baby gates, and other tools to control your dog‘s access when you can‘t supervise.
  • Educate all family members and guests about the risks of sharing grapes/raisins.
  • Be cautious with "grape flavored" pet products – while most don‘t contain real grapes, it‘s best to verify with the manufacturer to be safe.

FAQs About Grape & Raisin Toxicity
Q: Is grape juice or wine toxic to dogs?
A: Yes, juice, jelly, wine and other products made from grapes should also be avoided. The toxic component can leach into the liquid.

Q: Is it just the skin or the flesh of grapes that are toxic?
A: It‘s still unknown if the hazard comes from the skin, flesh, or seeds. To be safe, assume all parts are potentially toxic.

Q: What about grape seed extract?
A: Most grape seed extracts are made using the seeds, not the whole fruit. While they are likely safer than whole grapes/raisins, it‘s still best to avoid giving them to your dog.

Q: Do dogs actually like grapes or raisins?
A: Many dogs do seem to enjoy the sweet taste of grapes and raisins. However, some dogs are more interested in them than others. Always err on the side of caution.

Q: Are chocolate covered raisins extra risky?
A: Absolutely. The caffeine and theobromine in chocolate compound the risks of raisin toxicity. Even a small handful of chocolate raisins can be deadly to dogs.

In Summary
Grapes and raisins are highly toxic to dogs and can lead to acute kidney failure or even death if enough are ingested. Raisin toxicity can be especially dangerous due to the dried fruit being more concentrated. But even small numbers of fresh grapes can prove fatal for some dogs. There is no established safe dose for any dog.

If you suspect your dog has ingested ANY amount of grapes or raisins, call your veterinarian immediately. Onset of symptoms like vomiting usually occurs within 24 hours, but your dog may already have kidney damage before then. Aggressive treatment with IV fluids, activated charcoal, and anti-nausea medications can be lifesaving, but prognosis is always guarded. Prevention is truly the best medicine when it comes to grape and raisin toxicity.

As a veterinarian, my professional advice is to keep all grapes, raisins, and foods containing them far from your dogs. No matter how much they may beg, it‘s never worth the risk of losing them to this prevalent household hazard. Let my experience be your warning, and spread the word to your fellow dog lovers. Together, we can prevent more dogs from suffering this terrible toxicity.

References:

  1. ASPCA Animal Poison Control Center. Grapes and Raisins.
  2. DVM360. Toxicology Brief: Raisin/Grape Toxicity in Dogs.
  3. Pet Poison Helpline. Grape & Raisin Poisoning in Dogs.
  4. VCA Animal Hospitals. Grape and Raisin Toxicity in Dogs.

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