Q: Dear Dr. Hershey, why is chewing gum toxic to dogs?
Not all chewing gum is toxic to dogs, only gum containing xylitol is a concern. Xylitol is a sugar-free sweetener found in a variety of processed foods from mints to baked goods. Gum, however, is one of the most common products to contain this compound.
Xylitol is not toxic to humans, and it has never been reported as being toxic to cats. In the canine patient, however, xylitol can cause low blood sugar (hypoglycemia) and liver failure.
The effects of xylitol ingestion changes over a 24 hours period. In the first 12 hours after ingestion, we worry about xylitol causing hypoglycemia.
Humans are able to digest xylitol into a sugar alcohol that doesn’t affect insulin or blood sugar levels. In dogs, however, the pancreas confuses xylitol with real sugar, so it releases insulin.
Insulin drives sugar from the blood into the body’s cells. Since xylitol is not real sugar, the rush of insulin into the blood only serves to remove the real sugar from circulation leading to a dangerous drop in blood sugar levels. Signs of mild hypoglycemia can include weakness and possibly fainting. Severe hypoglycemia can lead to seizures and death. Hypoglycemia can occur within 30 minutes of ingestion of xylitol. The treatment for this condition is to keep the patient hospitalized on an IV glucose (“sugar”) drip until the effects of the xylitol have passed.
Xylitol can also have delayed reactions in the body. It can cause liver toxicity, but this doesn’t show up for about eight to 12 hours after the patient has eaten the xylitol. Also, a patient doesn’t need to get hypoglycemic first to then experience liver problems later. The mechanism of action as to how xylitol causes liver cell destruction is not fully understood, but if a patient has ingested enough xylitol, liver cells will begin to die.
The liver is responsible for filtering the blood, but also for producing blood clotting factors. A patient that is in liver failure will have nausea, vomiting, diarrhea and can sometimes have internal hemorrhage because they can’t clot their blood properly. Hospitalization with IV fluids and supportive care for the liver is important to help patients that are having liver toxicity from xylitol. The patient may also require a blood transfusion if they are having internal hemorrhage.
If your dog has ingested a product that is known to contain xylitol, it is important to bring your dog to the veterinarian immediately so vomiting can be induced and your dog’s blood sugar checked. Your veterinarian may also want to check blood liver enzyme levels. When possible bring the packaging of the product with you so your vet can determine how much xylitol your dog has ingested.
The toxic dose of xylitol for dogs is 0.045 grams per pound to cause hypoglycemia. A typical stick of gum contains 0.3–0.4 grams of xylitol. For an 8-pound dog, the toxic dose is 0.36 grams of xylitol, or 1 stick of gum. For a 60-pound dog, a toxic dose would be 2.7 grams, or about nine sticks of gum.
The dose to cause liver failure is higher, about 0.45 grams per pound (10 times higher). In this same example, an 8-pound dog would need to ingest 3.6 grams of xylitol (about nine sticks of gum), and a 60-pound dog would need to ingest 27 grams of xylitol (90 sticks of gum) to experience liver failure.
If you have any questions about xylitol toxicity, call your veterinarian, or you can consult with Pet Poison Helpline at 1-800-213-6680. (Please note, there is a charge to call Pet Poison Helpline for a consultation.)
Dr. Teresa Hershey is a veterinarian at Westgate Pet Clinic in Linden Hills. Email her your pet questions at firstname.lastname@example.org.