Buddy's been using your toothbrush for the past year....I thought you knew, Sweetie! Hilarious, right?
Dogs’ mouths are filthy too because they’re carnivores (or at least mostly carnivorous omnivores), and scraps of meat attract bacteria. OTOH despite their reputation rat bites are surprisingly clean, because their front teeth grow all the time and are constantly renewed, and they bite into wood a lot which polishes them up.
Wulff & Morgenthaler