It depends on your definition of ‘meat’ - there are plenty of poisonous insects - OK, they’re animals, but probably not what you had in mind. There are numerous poisonous fish and amphibians. There are crustaceans and molluscs that would be dangerous to eat, either because of inherent toxicity, or because they concentrate environmental poisons, or play host to toxic bacteria.
But if the list is restricted to mammals, I don’t think there are any that would actually be toxic if you just ate the muscle meat. Offal could be quite another matter - Polar Bear liver, for example, contains dangerously high levels of Vitamin A.