I googled. I can only find a reference to CEDAR trees in which the sap could be bad for animals. http://www.cliniciansbrief.com/news/...keep-pets-safe

On further reading, I can't really find any proof--no vets or other scientists saying that tree sap is toxic to cats. Always cat advocates saying it. Since my cat and many others have been doing it for years and years with no apparent ill effects, I don't see the point in panicking about it.

Karen