Grapes Raisins and Kidney Failure in Dogs

You have a healthy, happy young dog. All of a sudden you notice that your dog feels really sick and is urinating a lot. You rush to the veterinary clinic, looking for an answer. Your veterinarian starts asking questions to get a good history, and starts running tests. Blood work and analysis of urine seems to indicate that your dog is in acute kidney failure. How did that happen? Your veterinarian asks questions- is there any chance your dog got into anti-freeze? No. Lilies? No. Grapes? Yes.

There are a number of different toxins that can cause acute kidney failure in an otherwise healthy dog. Many drugs can predispose dogs to this condition. What most people don’t realize is that grapes and raisins can be deadly to dogs’ kidneys. In this article we will review acute renal failure (ARF), what to expect in a situation of ARF, and the role of grapes and raisins.

The term ‘acute renal failure’ simply means sudden kidney failure. This is opposed to chronic renal failure (CRF). CRF is a condition that commonly occurs in old cats, where the kidneys slowly lose their ability to function over a time period of years. On the other hand, ARF can occur in a matter of hours to days.

In every day life, in humans and other animals, the kidneys function to filter blood. In doing so, the kidney actually performs many functions. It regulates the amount of water in the body, to ensure that the body is not dehydrated, or conversely, is not ‘drowning’ in excess water. By doing this, it also influences blood pressure. The kidney also removes toxins from the bloodstream. These ‘toxins’ can be helpful drugs prescribed by your veterinarian, normal body products that would be toxic if they weren’t filtered, or actual toxic substances. In addition, the kidney helps to maintain the balance of essential electrolytes in your body, such as sodium, potassium, phosphorus, and calcium. When something goes wrong with your kidneys, all of the above functions are affected.

Acute renal failure has many causes. Infections or cancer of the kidney, severe dehydration, bladder stones, various severe illnesses, and of course toxins, can cause ARF. These are only a few of the causes. This is why it is sometimes difficult to distinguish the causes of the ARF. However, it is important for the veterinarian to determine the cause, because sometimes there is more than one problem to treat.

The cells of the kidney work very hard, and therefore need a lot of energy and blood flow. These cells are very susceptible to damage if their blood flow is compromised by one of the above causes. When these important cells begin to die, they lose their ability to function properly. They lose the ability to regulate water, remove toxins, and maintain the proper balance of electrolytes. We are lucky that the kidney has a large amount of ‘reserve’. This means that a kidney can afford to lose about half of its cells before it cannot function properly any more. Until about 50% of the cells die, the rest of the kidney can make up for the loss. After the kidney loses more than 50% of its cells, the animal is in renal failure. If this loss of cells happens quickly, the dog is in acute renal failure.

Renal failure begins with the inability of the kidney to concentrate the urine. That means the kidney is unable to preserve water. In this beginning stage the dog will urinate a lot, and try to drink a lot to keep up with the water it is excreting through its urine. The dog will begin to lose essential electrolytes. As kidney failure progresses, more kidney cells die because of poor blood supply due to dehydration and continued injury. The kidney begins to lose the ability to filter blood at all, and the dog begins to urinate less and less, and may actually get to the point where it cannot urinate at all. This is usually called end-stage renal failure. Your veterinarian needs to get involved long before this stage occurs.

So how do grapes and raisins fit in here? The truth is we don’t really know how grapes and raisins cause ARF in dogs. They don’t act like other toxins; that is, there is no predictable outcome after a dog eats them. For example, your veterinarian can calculate the ‘toxic dose’ of many substances, such as chocolate or Tylenol. The toxic dose is the amount of toxin per kilogram of body weight that the dog needs to eat in order to have harmful effects. There is no known toxic dose for grapes or raisins, because different dogs have different reactions. Some dogs could eat a whole bag of raisins with no problem, while another dog might eat bunch of grapes and become critically ill. It seems that the reaction to eating raisins or grapes varies unpredictably between dogs.

So what should you do if your dog eats some grapes or raisins? How do you know if your dog is going to have kidney damage? Unfortunately, you can’t predict which dogs may have ARF as a result of grape or raisin ingestion. Like the saying goes, you are better safe than sorry. The best idea would be to go to your veterinarian. If you catch your dog within two hours of eating it, you have a good chance of making your dog vomit most of it up. Your veterinarian may recommend other treatments, and may even recommend a hospital stay and fluids, just in case. Often however, your veterinarian will recommend getting your dog to drink as much water as possible, and monitoring for changes in urination. This way you can have your dog treated as soon as possible should a problem occur.

Acute renal failure due to ingestion of grapes or raisins is uncommon. However, it does occur and is something that you should be aware of. Remember that changes in urination (frequency, volume, or quality) can be caused by many different problems. If you notice any changes in urination, it is important that you take your dog to the veterinarian. Always be aware of the foods, chemicals, and drugs that are toxic for your animals. Most veterinarians carry information on common toxic substances for pets. If you have any questions about acute renal failure in dogs, or the role of grapes and raisins, contact your local veterinarian.