The answer is “it depends” – aspartame, for example, is probably more or less harmless in normal quantities (although it may cause a stomach upset!). However, xylitol is potentially lethal.
What is xylitol?
Xylitol is a sugar alcohol that looks, and tastes, almost exactly the same as refined sugar. However, it is much, much lower in calories, so it is widely used in low-calorie baking, medicines, and also in dental products because it reduces plaque buildup on the teeth.
Products that commonly contain xylitol include:
- Sugar-free gum (high levels of xylitol).
- Low-calorie or sugar-free cakes and biscuits.
- Low-sugar ready meals.
- Some supplements, especially children’s vitamin tablets (like the chewy vitamin C ones).
- A lot of sugar-free tablets have a xylitol base.
- Sugar-free or low-calorie peanut butter – watch out for this as it is thought to be one of the most common causes of xylitol poisoning in dogs!
How is it toxic?
In humans, xylitol is ignored by the body. However, in dogs it “tricks” the body into thinking that blood sugar levels are too high, resulting in a massive release of insulin. This results in hypoglycaemia (dangerously low blood sugar levels), which may result in a coma which rapidly becomes irreversible (as the dog’s brain is starved of fuel). Doses as little as 2g of xylitol or 1/12oz for a medium sized Labrador could be fatal. If higher doses are eaten, the dog may suffer acute liver failure. The mechanism by which xylitol damages the liver isn’t known, but it is a very real – and very dangerous – phenomenon.
What are the symptoms of poisoning?
Signs of hypoglycaemia may appear within 20-30 minutes, but are occasionally delayed by 12-18 hours (usually if the xylitol is bound in a slowly digested substance like chewing-gum). They typically include:
- Muscle weakness.
- Lethargy and depression.
- Fits or seizures.
- Coma, slow breathing and heart rate, and then death. The signs of liver failure usually take longer to appear (often 24-48 hours after ingestion) and are much more variable; however, they often include:
- Vomiting and (occasionally) diarrhoea.
- Jaundice (yellowing of the gums and eyes).
- Abnormal bleeding, causing bruises or a rash; blood in urine, faeces, or vomit; nosebleeds; or internal bleeds
Can it be treated?
There is no specific antidote for xylitol poisoning. If the dog has eaten xylitol recently (within an hour or so) but no symptoms have yet developed, we will usually induce vomiting to to limit exposure to the source.
If they are showing signs of hypoglycaemia, our aim is to artificially maintain their blood sugar levels at a safe level, with intensive care nursing, constant monitoring of blood sugar, and a glucose drip.
If they have developed, or are risk of developing, liver failure, all we can do is give supportive care, to try and support the liver and hope that it can recover. Supportive care would usually include hospitalization and drugs to support liver function.
Will affected dogs recover?
Dogs who receive treatment before symptoms appear have a good prognosis unless they’ve consumed truly vast amounts of xylitol; as do dogs with mild to moderate hypoglycaemia. Dogs developing significant liver disease tend to do a lot worse, and dogs who have lapsed into a coma before they are seen by a vet rarely survive.
If you think your dog has eaten anything containing xylitol, contact us IMMEDIATELY, even if they still seem well.