Many people use peanut butter as a snack or pill concealer for dogs. This is usually OK but some companies are using sugar substitutes in their products. Make sure you read your labels!
Xylitol is a sweetener that’s gaining in popularity because of its dental benefits for people as well as its suitability as a sugar substitute for people with diabetes. Because of its ability to help prevent cavities and tooth decay and its low glycemic index, xylitol is proving to have some good dental and other health benefits for people. Unfortunately, while xylitol appears to be perfectly safe for people, it is extremely dangerous for dogs — even in small quantities.
Ingestion of as little as 0.1 gram (g) of xylitol per kilogram (kg) of body weight (0.1 g/kg) can cause a rapid and dangerous drop in a dog’s blood sugar (a condition called “hypoglycemia”). Hypoglycemia can show as staggering, appearing disoriented, collapse, weakness, and seizures.
Just slightly more than that, approx. 0.5 g/kg xylitol ingestion, can lead to debilitating, and sadly often deadly, destruction of a dog’s liver cells.
These quantities, or toxic doses, are based on the data that the animal-specific poison control hotlines have collected from reported cases*. To highlight that these are reported cases is important, because not every case of toxicity makes it to the vet, and not everyone that does go to the vet is called into the animal poison control hotlines. So the actual toxic doses could be even lower, and dogs with certain pre-existing medical conditions (such as diabetes, hepatitis, and others) are likely to be even more sensitive to the toxic effects of xylitol.
*Sources: New Findings On The Effects Of Xylitol Ingestion In Dogs from ASPCA-APCC 2006; Acute Hepatic Failure And Coagulopathy Associated With Xylitol Ingestion In Eight Dogs from ASPCA-APCC 2006, published in JAVMA (J Am Vet Med Assoc 2006; 229:1113-1117)