It seems like artificial sweeteners have found their way into everything these days. They are not just found in diet sodas anymore! In addition to these so-called “diet” drinks, they are also found in baked goods, chewing gum, candy, canned fruit, salad dressings, jams, chewable vitamins, liquid cold medicines, mouthwash and even toothpaste! We humans like our sweets. While considered safe for humans, artificial sweeteners can be very dangerous to dogs. It is therefore crucial that those of us who share our lives and homes with dogs understand the dangers, and prevent exposures in dogs.
Artificial sweeteners are classified as either nutritive, meaning that they contain some calories, or non-nutritive meaning that they do not. Many were discovered by accident in laboratories when chemicals developed during experiments were discovered to taste sweet. It is actually kind of humorous to read how an accidental finger lick in a lab lead to the discovery of saccharin in 1879. Rather than elaborating on the various sweeteners and their properties, let’s just focus on xylitol since it is the sweetener with known toxicity in dogs.
As the waistbands of many humans have expanded over recent decades while the prevalence of diabetes has reached epidemic proportions, the quest to limit calorie intake from sugars and carbohydrates has broadened. Both the nutritive and non-nutritive sweeteners have found their way into many common foods and beverages since many consider this an effective strategy to eliminate extra calories and carbs. And while the debate over the safety of these sweeteners continues, they remain generally acceptable in human diets. That’s because in humans these sweeteners are not sensed by the pancreas, which does not secrete insulin in response. The end result is no insulin release, and no added calories.
The same is NOT true in dogs. While sugar alternatives do not add much energy or calories to a dog’s diet, they can stimulate a dog’s pancreas to secrete insulin. The sweetener called xylitol causes insulin release from dog pancreas cells just as sugar does. But unlike sugar, it does not cause a significant elevation in circulating glucose. This results in a lowering of the blood glucose to dangerously low levels. With the release of insulin from the pancreas it drives what glucose is in the blood into cells and tissues. The net result is a profound lowering of blood glucose below what supports normal physiology. The normal range of blood glucose in dogs is 75 – 120 mg/dL. In cases of xylitol exposure the blood glucose can drop to as low as 15-20 mg/dL. At these profoundly low levels, the brain begins to starve for energy, which causes neuronal cell death, seizure activity, and loss of consciousness. If left untreated, death will quickly follow. It is therefore absolutely critical that a dog that ingests any product containing xylitol be evaluated and treated by a veterinarian as quickly as possible after exposure. The veterinarian will closely monitor the dog’s blood glucose and provide IV glucose in response to low blood levels.
Next, let’s examine the types of products that contain xylitol. Xylitol is very interesting because it is known to decrease dental plaque in people and decreases oral bacteria that contribute to dental disease. These properties actually make its addition to toothpaste, mouthwash, and chewing gum beneficial. Not only does it decrease calories while adding a sweet taste, it promotes overall oral health. And it has a very wide safety margin in people. In fact, if people exceed more than 130 grams of xylitol daily (which is equivalent to 130,000 mg or 433 sticks of gum), the worst that happens is a little diarrhea. Now compare the numbers in dogs. In a 22 pound dog (10 kg) as little as 1 mg of xylitol can lead to extreme low blood glucose and death. One stick of chewing gum contains about 300 mg xylitol, which would exceed the toxic dose for 300 dogs each weighing 22 pounds!! Or more than 65 dogs weighing 100 pounds each. In one stick of gum!! What is absolutely frightening to me as a veterinary toxicologist is the fact that the FDA does not require drug companies to list xylitol as an active ingredient! Therefore, I uniformly recommend that everyone just assume that it is found in all over-the-counter liquid medications, toothpaste, and mouthwash. It is vital that every dog with an exposure be evaluated and treated by a veterinarian as soon as possible!! Do not hesitate even for five minutes to take your dog to a veterinarian if you suspect a xylitol exposure.
As with most toxic substances, prevention is key. And prevention just takes some common sense precautions. If you keep chewing gum in your home, I recommend that you seal it in a zip lock baggy or plastic container with a lid. This will help to prevent attracting dogs by the sweet smell. After placing all gum in an airtight container, place it in a cabinet on a high shelf. A high kitchen cabinet would be perfect. Only take out one piece of gum at a time, and then always return your gum supply back to its airtight container on a high shelf in a cabinet. Never leave gum on a countertop! If you carry gum in a handbag, always secure your handbag in a closet or cabinet to prevent dogs’ access. I know this seems like a lot of effort, but it literally takes a couple seconds to do, and potentially prevents pain and suffering that can lead to tragic endings without urgent veterinary care. Likewise, always store toothpaste and mouthwash inside medicine cabinets or drawers. Not only will these efforts prevent toxic exposures in dogs, they keep your home neat and tidy. Lastly, while walking your dog on sidewalks, never let your dog eat chewed chewing gum stuck on the pavement. Gum loses the xylitol once it has been chewed, but you never know how long that piece in the pavement was actually chewed before it was spit out. Oh, and just a reminder that if you chew gum yourself, always spit out chewed gum into garbage pales with lids.
This is Dr. John Tegzes, the Toxvet, wishing you a poison-free day!
John H. Tegzes, MA, VMD, Dipl. ABVT
Dr. John Tegzes is a veterinarian who specializes and is board-certified in Toxicology. He graduated from the School of Veterinary Medicine at the University of Pennsylvania, and completed residency-training in diagnostic and clinical Toxicology in the Vet School at the University of California, Davis. He has worked as a veterinarian in companion animal practices in Portland, OR, and in Toxicology at the Oregon Poison Center and the California Poison Control System. Currently he is a Professor of Toxicology in the College of Veterinary Medicine at Western University of Health Sciences in southern California. He resides in Los Angeles, California in the happy company of two dogs, two cats, and a sun conure.