Did You Know That Xylitol Sweetener Can Be
Very Dangerous To Your Pet ?
For another list of xylitol-containing product and more information, also go here
2015 - now also in some peanut butter
Ron Hines DVM PhD
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Over the last dozen or so years, the sugar substitute, xylitol, has become a common ingredient in commercial food products. Xylitol is made from wood and other types of cellulose, (although small, harmless, amounts are found naturally in fruit). It is a popular sugar alternative in baked goods, deserts, toothpaste, candy and sugar-free gum. It is a popular sugar substitute for diabetics and for weight loss programs. Although xylitol is as sweet as table sugar, it has one third less calories. Its mild anti-bacterial properties make it a popular cavity-fighter in chewing gums and toothpaste. You might easily have a xylitol-containing product in your home without even realizing it.
Although xylitol consumption appears to be harmless in humans, that is not the case in dogs. Dogs handle this sugar substitute differently. They absorb it more rapidly, it affects their insulin and blood sugar levels differently and it predisposes them to liver damage not seen in humans that consume xylitol. As the popularity of xylitol in human food increased (about 2002) the incidence of accidental xylitol poisoning in dogs began to increase too. (ref)
What About Sorbitol ?
How Common Is Xylitol Poisoning ?
Although the number of xylitol-related poisonings has increased, xylitol is not among the top ten poisoning dangers for dogs in the United States at this time (2012). Accidental consumption of human prescription medications tops that list. It is followed by insecticides and lawn and garden products, over-the-counter medications like Tylenol and ibuprofen, chocolate, household products, overdoses of veterinary medications, rat and mouse killer, house plants and automotive products. (ref) In the UK, human over-the-counter pain medications top the list, followed by rat and mouse bait, chocolate, paracetamol, insecticides, slug killer (metaldehyde), lilies (cats only) , grapes, electronics batteries and adder bites. (ref)
Does Xylitol Affect All Kinds of Pets The Same Way ?
Different species of animals absorb and metabolize xylitol differently. In some, it causes blood insulin levels to go up and blood sugar levels to become critically low. In other species, no toxicity occurs.
In home situations, xylitol is primarily a dog problem. I know of no reports of it causing toxicity in cats when given orally. We do not know if that is because they absorb and metabolize xylitol differently than dogs or because the taste of xylitol appeals to them less. It was actually tried as an additive to cat drinking water to decrease tartar formation – although at a level too low to form conclusions as to its affect on the cats blood sugar levels. (ref)
What About Ferrets ?
There is an online report of poisoning in a ferret that consumed xylitol. That report states that it occurred subsequent to the ferret eating Tic Tacs. The only Tic Tacs sold in the USA that contained xylitol were the mentholated Chill Exotic Cherry variety. They are the ones to the forefront of the photo at the top of this page. None of the Tic Tac mints sold in my town (in mid 2012) currently contain xylitol. However, several competing brands do contain xylitol. To the best of my knowledge, no cases of xylitol poisoning in ferrets have been reported to the ASPCA poison control site or the UK site since 2002. The Italian makers of this mint did not get back to me. Since younger ferrets are very prone to eat things they shouldn’t, it is surprising that there has been only one report. I have had ferret patients develop sudden, fatal liver damage (similar to that described in that one ferret) in the 1970s – long before xylitol was a common food ingredient. In those two cases, the ferrets had eaten urethane caulking that had not fully cured. I would very much appreciate an email from ferret owners who know of confirmed xylitol toxicities in ferrets. Until we know more, be sure to keep those products locked away from pet ferrets.
What Happens When Dogs Eat Xylitol ?
When you eat xylitol, your body absorbs it slowly, and when that occurs, your body recognizes that it is not table sugar. Once your body has converted all the table sugar (sucrose) to glucose, your pancreas releases insulin to metabolize that sugar and remove excessive amounts from your blood stream.
But when your dog eats xylitol, this sugar substitute enters its blood stream much faster and ,unlike your body, your dog’s body does not recognize that xylitol is not true sugar. The dog’s pancreas then releases large amounts of insulin to deal with it. This can cause a sudden, severe drop in your dog’s blood sugar level (hypoglycemia), similar to what diabetics experience if they take too much insulin. The classical symptoms of hypoglycemia in humans are weakness, confusion, tremors, twitching, staggering and even seizures. Those are exactly the symptoms you will see in your dog in this situation as well. The severely of the signs you will see in your pet will vary with the amount of xylitol consumed as well as the product it was incorporated in – some release the xylitol faster and more completely than others. So it is possible that all you would see is less interest in interacting with you and its environment (lethargy), perhaps some loss of appetite, vomiting and diarrhea. Poison control centers have also found that there is also a great deal of variation in how a similar dose of xylitol will affect individual dogs.
What Are Some Of The Products In My Home That Might Contain Xylitol ?
The list is very long and product ingredients change from time to time, but various brands of chewing gum, toothpaste, dietetic cookies, mints, specialty bread and baked goods, and products marketed as suitable for people with diabetes often contain xylitol. (ref) So can "low-cal" brands of peanut butter and yogurt. Check the ingredients label of these products carefully. Words that would alert you to be particularly cautious would be “Sugar Free”, “Dental”, “Diabetic Approved”, “Dietetic” "diet" or “Low or Reduced Calorie” (if sold in the United States, the word xylitol must be on the package lable of xylitol-containg products somewhere even if the print is very small).
Baked goods containing xylitol are particularly troublesome because dogs up to mischief can consume large product amounts. They are also troublesome because they utilize powdered pure xylitol that can be added in excessive amounts by specialty bakers and because the spongy, crumbly nature of baked goods leads to rapid absorption of the xylitol.
How Much Xylitol Does My Pet Have To Eat To Become ill ?
Any consumption or suspected consumption of xylitol is reason enough to visit your veterinarian to have things checked out. You could be wrong about the amount consumed, you or I might be wrong in our calculations or your pet may react to the ingestion in unanticipated ways.
Veterinarians believe that dogs that eat more than 45 mg per pound (100mg/kg) of their body weight are in danger of a sudden drop in their blood sugar level. One teaspoon full of one leading manufacturer's (Global Sweet) pure xylitol weighs close to four grams (4000mg). So a 20-pound dog should need to eat one-quarter teaspoon full of pure xylitol powder to potentially become ill. Data on the amount of xylitol in things like sugar-free gum are much harder to obtain, but Trident Original chewing gum is said by its manufacturer to contains about 170mg of xylitol per stick. Eating 4-5 sticks of gum could cause problems in a 20-pound dog. Other brands, like Orbits Spearmint, Peppermint and Lemonfresh contain more xylitol - about 285mg/1.9 gram stick. Other veterinarians have said that as little as one-and-a-half sticks of xylitol chewing gum could be injurious to a ten-pound dog.
When it comes to how much xylitol it takes to injure your pet’s liver, things are even less clear. The amount is definitely more than what it takes to make your pet’s blood sugar level drop – probably five to ten times as much. But there is much more dog-to-dog variability in the degree of liver damage that occurs and some dogs go on to develop liver problems without first experiencing dramatic changes in their blood sugar levels. You can read a study that explores the relationship between amount of xylitol consumed and the damage that occurs here.
You might detect a degree of uncertainty in what I have told you about how much xylitol is or isn’t dangerous to your pet. That is because the data has never been confirmed experimentally. It is based on sporadic (occasional) cases that are reported to the ASPCA pet poison control center and its counterpart in the UK. In those cases, the conditions under which the pet consumed the xylitol, timing in its relationship to the food in its stomach, variations in the dog's breed, age and general health, and, most importantly, the owner's rough estimate of how much product the dog may have consumed are all open to errors. So we might be erring on the side of caution - as medical people tend to do. Before 1965, research scientists in the Western World would simply have forced a known amount of xylitol into experimental research dogs and seen what happened. Those sort of studies are no longer performed. However, in China, a uniform group of Pekingese dogs were intentionally given 1 or 4 g/kg of xylitol. If the report is accurate, none of the dogs died and no mention is made of liver damage. You can read that study here. Make of it what you will, The author has not yet responded to my email.
What About Veterinary Products That Show Xylitol As One Of Their Ingredients ?
Pet dental hygiene products sometimes list xylitol as a minor ingredient. When consumed in the amounts suggested on the package, they pose no known health threat.
How Long Does It Take Xylitol To Affect My Dog ?
When a dog eats xylitol, the effects generally begin in 20- 30 minutes. The Chinese study found that the blood insulin level in these dogs was already rising in 20 minutes and peaked at 40 minutes. US studies have found that those rising insulin levels cause the dog’s blood sugar to begin to drop about a half hour after it eat the xylitol-containing product. The form the xylitol and the foods already present in the dog is in can also have an influence in how fast it is absorbed from the pet’s digestive system. That may account for a few cases in which the fall in blood glucose levels was delayed. How long the pet’s blood sugar stays critically low is also quite variable – so blood sugar levels might need to be monitored for an entire 24-hour period (longer if the xylitol is gradually being released from some confectionary product that disolves slowly).
If My Dog Ate Xylitol What Are The Signs and Symptoms I Might See ?
Non of the signs you might see would tell you for certain that xylitol was the problem – short of finding missing food items or torn packaging. But the first signs of ingestion are the typical signs of low blood sugar (hypoglycemia). A few dogs vomit, but that is not a consistent sign. Dogs suffering the effects of low blood sugar levels become less coordinated. They progress from apathy and disinterest in their surroundings and owner to depression. Depending on the amount consumed that can progress to collapse and even seizures. Some dogs develop diarrhea. You can read a description of a case in a Labrador retriever here.
Dogs that ingest (eat) large amounts of xylitol have a second more serious risk – in a substantial percentage of them, their livers sustain substantial damage. Although the biochemical signs of that damage (rise in blood liver enzyme levels) begin early, it can take a number of days for the full effects of that liver damage to become apparent. At that point, the signs can be no more than lingering abnormalities in the pet’s liver enzymes (in mild liver damage) all the way up to the signs of complete liver shut down and acute hepatitic (liver) failure. Dogs generally have to eat more than 500-1,000 mg/kg body weight of xylitol to be at risk of these severe signs. As with hypoglycemia, there is a great deal of variability in how severe the effects will be with any given dose. It is also not that uncommon for dogs to go on to liver damage without first showing signs of prior hypoglycemia (low blood sugar). Signs that a pet’s liver is in trouble are vomiting, disinterest is food, yellowing of the skin and eyes, increased bleeding and slowing of the blood’s ability to clot. You can read about a case in a Springer Spaniel and how it was managed here.
What First Aid Can I Administer On My Way To The Vet ?
Dogs that are not fully in control of their mental and physical capacities should not be induced to vomit. That is because they may well inhale food and stomach contents into their lungs in the process of heaving.
So if you can make it to the veterinarian in 15-20 minutes or less – just go there.
But if you are in a remote location, and your dog appears completely alert, you can often cause it to vomit back much of the xylitol-containing material it ate if it has been less than 30 minutes since it ate it. The best, readily-available product to do this is 3% hydrogen peroxide solution. It must be a fresh bottle - a drop of which will “frizzle” on your tongue - and it must not be the strong kind used to color hair, etc. If the dog will eat, hydrogen peroxide works best on a full stomach –something spongy like bread. The accepted dose is 1 teaspoon or 5ml per 10-15 pounds body weight. But I usually give only a teaspoon full to a 30-50 pound dog and wait to see if that is not sufficient – less than a teaspoon full for toy breeds and I limit the total amount to three teaspoons full regardless of weight. A dog that is beginning the upchuck process usually begins to salivate, foam and heave in 5-15 minutes. The hydrogen peroxide can be repeated. It might also be advisable to give frequent small amounts of oral sugar solution (to a fully conscious dog) if no veterinarian will be available.
If two hours or more have passed since the pet ate the xylitol, inducing it to vomit is unlikely to help as the stomach contents have usually moved to far down the intestine to be regurgitated (upchucked). (If no veterinarians are available in your part of the World, you might consider giving pet that are still fully lucid frequent small meals and oral sugar.)
How Will My Veterinarian Diagnose A Xylitol Problem In My Pet ?
None of the signs of xylitol toxicity are specific – they could all be caused by a number of other health conditions. So veterinarians can easily overlook the possibility if the owner does not hint that the dog ate a product that is known to contain xylitol or that the dog has a history of eating things it shouldn’t.
In most perplexing non-traumatic cases that veterinarians see, they begin with an analysis of a sample of the pet's blood. The red flag result (if sufficient time has passed) is a lower than normal blood glucose level. When the amount of xylitol consumed was substantial a liver enzyme (ALT) and blood bilirubin usually rise. Blood thrombocyte numbers often drop and tests that measure the rapidity with which the dog’s blood clots become abnormally long. (prothrombin time, partial thromboplastin time, clotting time). The pet’s blood potassium, phosphorus and calcium levels might be abnormal as well. If the poisoning occurred a number of days prior to admission and the amount consumed was substantial evidence of abnormal bleeding (bruising, nose bleeds, bloody stool or vomit) and liver failure can be present as well. (icterus, petechia, ecchymosis)
Are There Other Health Problems That Might Cause Similar Signs ?
There are other things that can cause a sudden, unexplained drop in blood sugar and weakness. Insulin injection overdose or consumption of human anti-diabetic medication, insulin secreting tumors of the pancreas (insulinomas – pancreatic beta cell tumors), failure to eat adequately or frequently enough, a dysfunctional liver, insufficient cortisone (Addison’s) could present themselves with similar signs.
Later signs related to liver damage could be confused with acetaminophen (Tylenol) poisoning, consumption of rat and mouse poison, and, more rarely, ingestion of liver-toxic plants like poisonous mushrooms (amanita), moldy grains (aflatoxins), algae-contaminated water (cyanobacteria) , infections like leptospirosis or toxoplasmosis or certain cancers.
How Will My Veterinarian Treat My Pet ?
Your veterinarian might induce your dog to vomit if not too much time has passed. The vet might also give a universal antidote containing charcoal – although there are doubts as to its effectiveness against xylitol. Some vets attempt to wash out the pet’s stomach (gastric lavage) when dogs arrive soon after eating the xylitol.
Early in a xylitol poisoning case, your veterinarian will be dealing with, or anticipating a serious drop in your dog’s blood sugar level. Your veterinarian will attempt to correct or minimize that by administering a slow, intravenous solution of glucose with frequent monitoring of the pet’s blood sugar level. The same blood samples used to monitor the pet’s blood sugar level will also be checked for abnormalities in its blood potassium and phosphorus – components that are commonly affected (hypokalemia, hyper or hypophosphatemia) . Close monitoring allows the vet to add whatever support is necessary to keep the pet comfortable. Vomiting and indigestion can be controlled with a number of medications (metoclopramide, famotidine, sucrafate).
Once your veterinarian has your pet hooked up to an IV drip (intravenous infusion of liquid) and your pets blood sugar levels are no longer critically low, the vet will turn his/her attention to the more worrisome side effect of eating xylitol. That effect is liver damage.
Liver damage due to xylitol ingestion is highly unpredictable. It
will occur in one dog, but not in another that eats the same amount.
In some dogs it will be severe and resistant to treatment, in others
mild and transient, in others occurring not at all. But the greater
the amount of xylitol the pet ate, the more likely it will be to
occur. Blood test values your veterinarian will be particularly
interested in are its ALT (alanine aminotransferase)
bilirubin and alkaline phosphatase levels. The vet will also closely
watch for signs that liver damage has affected the ability of your
pet’s blood to clot. At the slightest indication that the
pet’s liver is in danger, and often as a precautionary measure
before signs begin, vets often begin the animal on a medication
that is thought to perhaps protect the liver (SAMe.)
If the pet’s blood no longer clots as it should, blood plasma or blood products are often given in an attempt to correct that. Vitamin K1 is often given as well.
Liver problems due to xylitol take longer to assess than low blood sugar. While dogs get out-of-the-woods in a day or so with respect to their blood sugar levels (hypoglycemia) , their livers needs to be monitors for at least 2-5 days. If there were signs of liver damage, your vet might suggest a low protein, liver-protective diet for a while. You can read other articles that discusses xylitol ingestion treatment here, here , here , and here .
In many cases, you may have brought your dog to your veterinarian not knowing what was the cause of its sudden illness. Without clues from you, your vet may be perplexed too. So do not be surprised if you veterinarian administers many other medications to protect your pet from many conceivable causes for the symptoms he sees.
Will My Pet Recover ?
Dogs that consume small to moderate amounts of xylitol usually recover with no lasting injuries. Veterinarians have good ways to manage dangerously low blood sugar until the pet’s insulin levels return to normal. But if the dog is brought to the vet already in a coma, experiencing severe hypoglycemic seizures or if during a seizer or violent vomission, food from its stomach was inhaled into its lungs its outlook is more clouded.
Dog that develop liver damage (hepatotoxicosis) due to xylitol are at a much greater risk for death. Your pet’s liver has remarkable capabilities of regeneration; but that requires that some of its liver cells were spared the toxic effects of xylitol. Only time and supportive care will tell us that. It is also clear that the livers of some dogs are damaged more by the same dose of xylitol than others. We do not know why that is so. But once your pet’s liver tests start to return to normal level, he should be coming home soon.