If eaten by dogs, Xylitol causes a sudden release of insulin, which can lead to hypoglycaemia (low blood sugar), intestinal bleeding and liver failure. Signs of low blood sugar can include vomiting, weakness, difficulty walking, trembling or even fits. Immediately veterinary attention should be sought if your pet show any of these signs.
It is thought that cats and ferrets could be vulnerable to poisoning by the substance. However as cats do not taste "sweet" in the way we do, they are less likely to seek it out, although they might be attracted to dairy products such as ice cream which could contain it.
We would advise all our clients to be careful what sort of human food their pets have access to. Do not feed your dog any human food containing Xylitol, and of course avoid other toxins such as grapes, raisins and chocolate. Poisonings often occur because dogs raid unexpected sources of food; beware breath freshening gum, or that emergency bar of chocolate which lives in your handbag.