This vsauce video is about humans, but I imagine pretty much every mammal will be just about topologically equivalent. As it turns out we humans have quite a few more holes than fleshy donuts would.
Great vid! (Was rather cringe though when he eats the toilet dunked donut. Some years ago I recall the Exploratorium science museum in SF had a psychology exhibit consisting of a toilet drinking fountain made from a toilet that had never been used. The question posed was, if you aren't willing to drink from the toilet fountain, why not? It's hard to articulate why so many of us find it gross even if we are logically perfectly aware there isn't a sanitary risk.)