Dr. Nancy Kay, DVM, DACVIM
For some folks, the start of a new year is a catalyst to lose weight and this may mean switching from plain old sugar to lower calorie sweeteners. Xylitol is one such sugar substitute that is safe for human consumption, but is toxic for dogs. In fact, it can be deadly.
What exactly is xylitol?
Discovered by German chemist Emil Fisher in 18911, xylitol is found in fruit and vegetable fibers. It is commonly referred to in labels as "birch sugar." The xylitol we consume is manufactured by beginning with a product called xylan found in hardwood trees and corncobs, hence the name "birch sugar."
Xylitol was first put to use as a sweetener in Finland during World War II when sucrose was unavailable. The growth in xylitol popularity is attributed to its many beneficial properties. To begin with, xylitol is as sweet as sucrose, but with far fewer calories. Additionally, compared to sugar, it causes very little insulin release in people and insulin is not required for it to be put to use as an energy source for the body. Lastly, xylitol has been shown to prevent mouth bacteria from producing acids that damage the surfaces of the teeth. For this reason, xylitol is commonly included in toothpastes, sugar-free gum, and other oral care products.
Species-specific effects of xylitol
The effect of xylitol on insulin release varies dramatically between species. In people, rats, horses, and rhesus monkeys, xylitol causes little to no increase in insulin release or change in blood sugar levels. This is altogether different in dogs, cats, cows, goats, rabbits, and baboons. In these species xylitol causes a marked increase in insulin release and drop in blood sugar and is the basis for xylitol toxicity.
Xylitol toxicity in dogs
After a dog consumes a significant amount of xylitol, there is a massive release of insulin from the pancreas. This, in turn, results in a dangerously low blood sugar level and symptoms such as weakness, trembling, seizures, collapse, and even death.
At higher dosages, xylitol can cause massive liver destruction (known as necrosis) in which large numbers of liver cells die abruptly. This produces an acute health crisis and, in many cases, death.
Vomiting is often the first symptom of xylitol toxicity. Other symptoms related to the low blood sugar level develop within 30 minutes to 12 hours following consumption. When xylitol-induced liver damage occurs, blood liver enzyme values typically begin increasing within 12 to 24 hours.
The dose of xylitol considered to be toxic for dogs is 0.1 gram or more of xylitol per kg of the dog’s body weight.
What about cats and xylitol?
While xylitol ingestion in cats does cause a drop in blood sugar, this rarely happens. This is because, unlike dogs, most kitties have very discriminating palates- they don’t choose to eat products containing xylitol.
Treatment of xylitol toxicity in dogs
Emergency treatment is warranted after a dog consumes xylitol. If vomiting can be successfully induced within the first 30 minutes or so (before the xylitol leaves the stomach), the problem may be solved. Once xylitol leaves the stomach (the other way) and triggers the pancreas to produce insulin, intensive treatment is warranted in order to try to counteract the effects of hypoglycemia (low blood glucose) and liver damage. Treatment includes hospitalization with round-the-clock care, blood monitoring, and administration of intravenous glucose and liver-protective agents. In some cases, blood transfusions are needed to counteract the effects of blood clotting abnormalities caused by liver failure.
The prognosis for xylitol toxicity varies and depends on how promptly the dog receives treatment as well as the amount of xylitol that was consumed.
Read labels carefully
Many foods and dental products contain xylitol or birch sugar. Some commonly used products that may contain xylitol include:
Not all product labels clearly state if they contain xylitol. If a label states only, “artificially sweetened,” presume that it contains xylitol. If you opt to use xylitol-containing products in your household, be sure to keep them completely out of your clever dog’s reach.
What to do if your dog eats xylitol
If you believe that your dog has just eaten (as in you just watched it happen) something containing xylitol, contact a veterinary hospital staff member right away. You might be advised to induce your dog to vomit at home. This is accomplished by forcing your dog to swallow hydrogen peroxide.
If you’re not really sure when the xylitol was consumed (you’ve just returned home from work and the remains of sugar-free gum wrappers are decorating the couch), transport your dog to a nearby veterinary clinic or 24-hour emergency hospital right away. Be sure to take the label of the consumed product with you. Time is always of the essence when treating xylitol toxicity.
Look around your house and see if you have any xylitol-containing products. What did you find?