Toxic to dogs and sugarbirds Print E-mail
News - Rubrieke
Sunday, 27 September 2015 17:45
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Dr Liesel van der Merwe is a small animal medicine specialist. Send her your questions: This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Dr Liesel van der Merwe

Just because it’s safe for humans, doesn’t mean it’s safe for other species. Xylitol is a natural substance which is widely used as a sugar substitute. It is found in berries, plums, corn, oats, mushrooms, lettuce, some hardwood trees and fruits.

Most xylitol is extracted from corn fiber, birch trees, hardwood trees and other vegetable material and is made into a white powder which looks and tastes similar to sugar. Sugar-free gum, sweets, breath mints, baked goods, cough syrup, children's chewable vitamins, mouthwash and toothpaste may contain xylitol.

Xylitol is safe for humans. When eaten in large amounts, it may have a mild laxative effect when first introduced to a diet, until the digestive system adapts. However, it is extremely toxic to dogs. Even small amounts can cause low blood sugar (hypoglycaemia), seizures, liver failure or even death.
In both humans and dogs, the level of blood sugar is controlled by the release of insulin from the pancreas. Xylitol does not stimulate the release of insulin from the pancreas in humans.

When non-primate species (such as dogs) eat something that contains xylitol, the xylitol is quickly absorbed into the bloodstream, resulting in an exaggerated release of insulin (six times more than normal sugar), which results in a rapid and severe decrease in blood sugar levels. This occurs within 10-60 minutes of eating the xylitol. If untreated, it can be life-threatening.

The dose of xylitol that can cause hypoglycaemia in dogs is 100 mg per kg. As the ingested dose increases, (400 mg/kg weight) so does the risk of liver failure.

The most common source of xylitol poisoning comes from sugar-free gum. As there is a large range of xylitol in each different brand and flavour of gum, it is important to identify whether a toxic amount has been ingested. With certain brands of gum, nine pieces of gum can result in severe hypoglycaemia in a 20 kg dog, while 45 pieces would result in liver failure. With other brands, which contain 1 g/piece of gum, only two pieces would result in severe hypoglycaemia, while 10 pieces can result in liver failure.
Signs of hypoglycaemia may include: vomiting, weakness, difficulty walking or standing (walking as if drunk), depression or lethargy, tremors, seizures and coma. In severe cases, the dog may develop seizures or liver failure.

A presumptive diagnosis of xylitol poisoning is made if there is a known or possible history that the dog ate something containing xylitol, coupled with symptoms of hypoglycaemia. Since toxicity develops rapidly, your vet will not wait for a confirmed diagnosis before beginning treatment.

There is no antidote for xylitol toxicity. Fast and aggressive treatment by your vet is essential to effectively reverse any toxic effects and prevent the development of severe problems. If your dog has just eaten xylitol but has not yet developed any clinical signs, your vet may induce vomiting to prevent further absorption, depending on what your dog's blood glucose level is.

If clinical signs have developed, treatment will be based on the symptoms. In all cases, your dog will require hospitalization for blood sugar monitoring, intravenous fluids and glucose supplementation, liver protectants, and any other supportive care that may be needed.

The prognosis for dogs with hypoglycaemia is good with immediate and proper treatment, but it is poor for dogs that have developed liver toxicity.

Xylitol's effect on blood glucose varies greatly among species. In people, rats, horses and rhesus monkeys, intravenous xylitol causes little to no increase in insulin release or changes in blood glucose concentrations. However, it can cause large insulin release in cows, goats, rabbits, and baboons. Its effect on cats and ferrets is unknown.

The vet at the Johannesburg zoo recently examined the bodies of 30 Cape Sugarbirds that had died within 30 minutes of drinking a solution made with xylitol, from a feeder. The home owner had bought the xylitol for a diabetic family member and was unaware that it was toxic for birds. The vet suspected that the xylitol triggered a huge insulin release, causing an irreversible drop in blood sugar.


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