Eirevet is a veterinarian specialized in canine and feline internal medicine who owns a small animal veterinary hospital in Ireland.
Why Are Grapes Poisonous to Dogs?
Although it is now well established that ingesting grapes or raisins is a common cause of kidney failure in dogs, the phenomenon has only been recognized over the last three decades. Undoubtedly, there were many cases prior to this, but improved record-keeping and computerization of animal medical records allows for collation and documentation of the problem. Because these animals often have kidney failure, and the cause of kidney disease is usually very difficult to establish clinically, many historical cases would have been recorded as renal failure of unknown origin (idiopathic renal failure).
Unfortunately, we are still not entirely sure what substance within the fruit is toxic to dogs, but toxicity is likely due to the toxins produced by fungus or must on the skin, rather than the grape itself. These mycotoxins then cause death of tubular cells in the drainage system of the kidneys, and leads to more severe illness.
What Is the Toxic Dose?
The number of grapes needed to produce signs of illness will probably vary depending on the amount of fungal growth found on the fruit. Because raisins are essentially concentrated grapes, it takes far fewer of them to cause problems. Although other sources estimate that it can take about 10 grapes per kilogram of bodyweight, I have a colleague that recently dealt with a fatal poisoning in an adult Labrador that had eaten only one small child's packet of raisins. My own Labrador puppy developed signs of mild renal insufficiency, requiring intensive treatment after eating approximately 15-20 grapes, which would have equated to about one grape per kilogram. I would always urge caution when dealing with a dog known to have definitely eaten any amount of the fruit.
What Are the Signs of Grape Poisoning?
Although the most serious problems arise as a result of acute kidney failure, the initial signs seen after ingestion are usually vomiting and diarrhea. Your dog is also likely to be depressed and quieter than usual. After one or two days, you may notice an increase in your pet's thirst, and dehydration may be obvious with sunken eyes, a dry mouth, and prolonged skin tenting if the skin on the back of the neck is lifted.
Without treatment, it is possible for the symptoms to progress to severe kidney failure, with a lack of urine production and abdominal pain. A build up of nitrogenous waste products in the blood can cause foul-smelling breath, ulcers in the mouth, and shortness of breath. Severely affected pets may have seizures before death ensues.
Grape Toxicity Poll
Tip: How to Make Your Dog Vomit at Home
Do not induce vomiting without first consulting your vet. However, under their direction, most animals can be made to vomit by administering 1ml/kg of 3% hydrogen peroxide (available from drugstores) using a syringe or turkey baster. This can be life-saving if you cannot get them to surgery within the two-hour 'golden period' following ingestion.
If My Dog Ate Grapes Can He Be Treated?
Yes! However, as with most poisonings, time is of the essence. If you can bring your dog to your veterinarian within two hours of ingestion, then they can induce vomiting to prevent some or all of the toxins being absorbed. Feeding the dog activated charcoal or other protectant can also help prevent absorption in the early stages.
Further treatment in later stages involves supporting kidney function with intravenous fluids and electrolyte supplementation. If a large amount of toxins have been eaten, then more intensive measures may include blood pressure monitoring and manipulation, as high blood pressure is a common complication with severe renal damage after grape poisoning. Dialysis or kidney transplantation are sometimes necessary to ensure a good outcome.
Ultimately, the prognosis for a dog that has eaten grapes depends on two things: how long has passed before treatment is initiated, and how many grapes or raisins were ingested. Not all animals that eat a few grapes will show signs of serious illness, but many will, and you should always seek veterinary attention immediately if you suspect or know that your pet has been poisoned,
Your observations of your pet are vital, as there is no specific test to determine whether an animal has eaten grapes, but other clinical and laboratory tests such as blood pressure measurement, blood chemistry and cell counts, and urine analysis are vital in order to provide optimal care, so be prepared for your veterinarian to recommend that these are carried out for diagnosis and monitoring.
This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.
Has Your Dog Eaten Grapes?
Karen on August 30, 2020:
My medium sized dog 11kgs has eaten four small grapes will she be okay ?
Aby on October 29, 2019:
I let my dog eat 3 half piece of grapes pls help me I need to know what to do will he die?!?
Peggy pigeon on October 06, 2019:
My little 14 year old chihuahua ate a nail size peace of a green group what do I do
Karen foster on August 08, 2019:
My 10year old dog has ate 1 grape. Shes eating but not drinking. Need advise please
A on June 13, 2019:
We called the vet and she said to make my dog throw up so we did and she threw up. But I am scared she won’t make it. I don’t know. I just gave her a grape because she looked hungry and she has an adorable face. I am praying tonight but I am terrified
Alex on January 23, 2019:
i'm scared i don't know what to do he is a shit zu he might die should we go to the vet but he is very happy after i don't know if it's good or not but right now i'll just pray for him cause if he dies it will be all because of my fault
Jose on December 13, 2018:
My dog ate some grapes and unfortunately is deceased! I was with him the whole time and tried to make him as comfortable as possible but it wasn't a pleasant way to go. Extremely hard to watch, especially when its a pet that has bonded so tight with the family. Very very sad...
Clarissa on November 17, 2018:
My puppy ate 5 grapes and is about 25ibs she is a bully she ate the Thursday night and it's Saturday she is normal just pooping nasty and watery should I take her to a vet?
Angela on October 18, 2018:
I think my dog ate a grape on sunday and now he is dead.. my heart is broken.