Xylitol Toxicosis in Dogs

Summary

In dogs, sufficiently high doses of the common sugar substitute xylitol are toxic because they trigger a rapid release of insulin that drops blood sugar levels dangerously low. In rare cases, xylitol also causes life-threatening liver damage. 

Symptoms of hypoglycemia begin approximately 30 minutes after ingestion and include inactivity, vomiting, seizures, and loss of consciousness. The rare liver syndrome associated with xylitol toxicosis takes days to develop and is characterized by vomiting, appetite loss, and jaundice. 

Dogs who are made to vomit as quickly as possible after ingestion have the best prognosis. Treatment includes administration of dextrose and monitoring blood sugar and liver function. Dogs with uncomplicated hypoglycemia generally recover, but dogs that develop severe hypoglycemia or liver injury have a poorer prognosis. Since xylitol is toxic to dogs, preventing access to products containing it is essential.

Risk Factors

Xylitol ingestion is historically one of the ten most common toxicities reported to pet poison helplines each year. Calculating the dose ingested is useful when a dog is caught in the act of eating a food or product containing xylitol, as action is only needed when a toxic dose is consumed. These calculations can be complicated because manufacturers don’t always put the xylitol content on the label. Veterinarians, pet poison hotlines, and manufacturer customer service phone numbers can be helpful for finding this information.

The challenge for dog owners is the concentration of xylitol present in the product is not typically listed on the package, so it is hard to ascertain if the dog has consumed enough to be dangerous. Vets and pet poison hotlines keep published data on hand for some commonly consumed products, and sometimes manufacturers are also helpful when contacted at the phone number provided on the package.   

Depending on the total quantity of xylitol consumed, it’s possible for a small dog to be poisoned by a single stick of gum. Product packaging and labels are helpful resources to the attending vet when a dog is presented for care. Dogs who have consumed products with sufficient xylitol require immediate care from a vet. Do not wait for symptoms to develop before seeking care. The prognosis worsens the more time passes between ingestion and treatment.

A dog who is showing symptoms of hypoglycemia or liver damage is in danger.  Emergency medical care is urgently required.

Possible Causes

Xylitol poisoning is caused by ingestion of a toxic dose of xylitol. As with any form of poisoning, the dosage consumed determines whether symptoms of toxicity develop or not. Xylitol is found naturally in some foods, including berries, oats, lettuce, and plums, but not in sufficiently high amounts to make them dangerous for dogs. Xylitol is commercially manufactured for use as a sweetener in many food items (candy, gum, peanut butter, baked goods) and common drug store items (sunscreen, deodorant, toothpaste, medication, cosmetics, chewable vitamins and supplements, and oral hygiene or hair care products). Most cases of xylitol toxicosis in dogs result from eating gum and chewable vitamins.

Main Symptoms

The main symptoms of hypoglycemia due to xylitol toxicosis are:

• Vomiting • Weakness • Ataxia • Dullness • Recumbency • Lethargy • Seizures • Coma

The main symptoms of liver injury, which may or may not be preceded by hypoglycemia include: 

• Lethargy • Vomiting • Jaundice • Tiny purple or red spots on the gums

• Bruising all over the body with no known cause

Detailed Characterization

Compared to humans and other animals, dogs respond differently to xylitol by rapidly releasing a proportionally high amount of insulin which in turn leads to low blood sugar (hypoglycemia).   In most dogs, symptoms of severe hypoglycemia - vomiting, weakness, lethargy, seizures, and/or coma - develop around 30 minutes after ingesting more than 30 milligrams of 1 milligram of xylitol for every pound of the dog’s weight (75 mg/kg of body weight). In some cases symptoms may take up to 12 hours to develop.

For reasons that are not fully understood, some dogs (1 in 1000) develop severe liver injury 24–48 hours after ingesting more than 220 milligrams of xylitol per pound of body weight (500 mg/kg). Hypoglycemia does not always precede this. There is no correlation between the size of the dose and the likelihood of developing this rare complication, but it carries a mortality rate of at least 70%. Symptoms include lethargy, vomiting, jaundice, and abnormal bleeding.

Testing and Diagnosis

Handling a case of xylitol toxicosis depends on if the ingestion is known or not, how much time has elapsed since ingestion, and if the dog is showing clinical signs of poisoning.  

If the dog is showing clinical signs upon presentation and ingestion is not known, the dog receives the typical diagnostic workup warranted by its symptoms:  physical examination, bloodwork, urinalysis. There is no specific test to diagnose xylitol toxicosis, but evidence of low blood sugar or liver damage suggests it. 

A dog who develops clinical signs of either low blood sugar or liver damage after known ingestion also receives a similar diagnostic approach, but appropriate treatment is hastened. 

A dog presenting for veterinary care more than 4 hours after ingestion but who is still acting normal undergoes baseline blood work to monitor trends and catch signs of toxicosis early.

Steps to Recovery

Dogs presenting without clinical signs within less than four hours of ingestion undergo decontamination (induction of vomiting or gastric lavage) if a sufficiently large ingestion is suspected. Baseline blood values are collected and the ongoing plan for monitoring and treatment depends on the effectiveness of decontamination.

Treatment for hypoglycemia involves: 

• Ongoing monitoring of blood sugar levels • Offering frequent meals

• Administration of IV dextrose (sugar) as needed

Treatment of liver damage typically requires intensive care and aggressive symptomatic management of the gastrointestinal, neurologic, and blood disorders that result.   The prognosis is dependent on the dose ingested and effectiveness of decontamination. The prognosis is good for dogs that are treated before clinical signs develop, or for dogs that develop uncomplicated hypoglycemia that is quickly reversed. If liver failure develops, the prognosis is guarded to poor.

Prevention

All types of poisoning in dogs are prevented by eliminating access and exposure to toxins. In the case of xylitol, strategies to ensure prevention include:

• Read product labels and avoid products with xylitol • Do not share human food with dogs

• Use only toothpaste formulated for dogs 

• Store products that contain xylitol in closed containers out of reach of dogs

Is Xylitol Poisoning Common in Dogs?

Given the increasing prevalence of xylitol in many household products, the number of dogs who eat sufficient amounts to cause xylitol toxicosis is also on the rise. Xylitol is one of the top ten most frequent poisonings in dogs.

Typical Treatment

• Emesis induction (<4 hours after ingestion and prior to onset of symptoms) 

• Administer dextrose, intravenously as required • Monitor blood glucose levels • Monitor liver enzyme values

• Manage hepatic insufficiency/failure if it develops

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