This is similar to chocolate in dogs. As in, it needs fairly large levels to be toxic. It's also naturally occurring in some fruits, particularly raspberries. As far as the toxicity in gum, peanut butter, toothpaste (including dog toothpaste), etc., in a Lab sized dog you'd need more than what you get in peanut butter. However, I still wouldn't buy peanut butter that had it in it. My DH is a brittle diabetic, so he does limit the peanut butter to plain. Which means peanuts only, no added ingredients. Tanya, some of the more popular brands add the sugar to enhance the taste. Personally, like you, I'd rather stick to peanuts only.
From the Ask a Vet center where the question was asked about it in fruit:
Is natural xylitol in fruit toxic to dogs? | Ask A Vet
And from my personal vet's favorite recommended site (Veterinary Partners):There are some fruits that naturally contain xylitol but the amount of xylitol in the fruit is miniscule. This study says that raspberries are one of the fruits with the highest amount of xylitol. They contain 400 ug (micograms) of xylitol per gram of raspberry. So, let's say a dog ate 1 cup of raspberries. 1 cup of raspberries is about 123 grams of raspberries. So, this would equate to 0.05 g of xylitol.
(To do this math I converted 400 ug to g which is 0.0004 g. Then, I multiplied 0.0004 x 123 to get 0.05 g.)
So, how much xylitol is toxic to dogs? Xylitol can cause low blood sugar when given at a dose of 0.2-0.4g/kg. So, let's say you have a 10kg (22 lb) dog. This means that 2-4 g of xylitol could cause low blood sugar.
Low blood sugar at this level is not likely to be fatal. Xylitol can cause severe liver damage (and death) at a dose of 1.6-2g/kg. So, that means that a 10kg dog would have to eat a minimum of 16g of xylitol to be fatal.
So, let's put this all in context. One piece of xylitol gum contains 1-2g of xylitol per piece. In our 10kg dog, as 2-4 grams could cause low blood sugar, this means that two pieces of gum could cause low blood sugar. As the fatal dose of xylitol for this dog is 16 g, then possibly 8 pieces could be fatal.
Now, let's go back to the raspberries. There are 0.05 g of xylitol in 1 cup of raspberries. This means that in order to eat enough raspberries to cause hypoglycemia (low blood sugar) a 10kg dog would have to eat 4-6 cups of raspberries. To eat enough rasberries to be fatal, that same dog would have to eat at least 32 cups of raspberries!
So, it's all about dosage. Many dog toothpastes contain xylitol and I often get asked why such a toxic chemical would be in a dog toothpaste. It is because the amount is tiny as compared to the toxic dose.
01 Xylitol Poisoning - VeterinaryPartner.com - a VIN company!
Two Deadly Effects of Xylitol
Hypoglycemia
In the canine body, the pancreas confuses xylitol with real sugar and releases insulin to store the sugar. The problem is that xylitol does not offer the extra Calories of sugar and the rush of insulin only serves to remove the real sugar from the circulation. Blood sugar levels plummet resulting in weakness, disorientation, tremors, and potentially seizures.
It does not take many sticks of gum to poison a dog, especially a small dog (see below for toxic doses). Symptoms typically begin within 30 minutes and can last for more than 12 hours. Vomiting and diarrhea may also occur.
Hepatic Necrosis
The other reaction associated with xylitol in the canine body is actual destruction of liver tissue. How this happens remains unknown but the doses of xylitol required to produce this effect are much higher than the hypoglycemic doses described above. Signs take longer to show up (typically 8-12 hours) and surprisingly not all dogs that experience hepatic necrosis, will have experienced hypoglycemia first. A lucky dog experiences only temporary illness but alternatively, a complete and acute liver failure can result with death following. Internal hemorrhage and inability of blood to clot is commonly involved.
How Much Xylitol Is Dangerous?
The hypoglycemic dose of xylitol for dogs is considered to be approximately 0.1 grams per kilogram of body weight (about 0.045 grams per pound). A typical stick of gum contains 0.3 to 0.4 grams of xylitol, which means that a 10 lb dog could be poisoned by as little as a stick and a half of gum.
The dose to cause hepatic necrosis is 1 gram per kilogram of body weight, about ten times more than the above dose. In the example above, the 10 lb dog would have to find an unopened package of gum and eat it for liver destruction to occur.
Treatment
Ideally, the patient can be seen quickly (within 30 minutes) and can be made to vomit the gum or candy. Beyond this, a sugar IV drip is prudent for a good 24 hours. Liver enzyme and blood clotting tests are monitored for 2 to 3 days. Blood levels of potassium are ideally monitored as well. Elevated blood phosphorus levels often bode poorly.