If this is really a big problem I wonder if a brand could come up with a mix of Bitrex (https://en.wikipedia.org/wiki/Denatonium) and one of those deodorizers/fresheners you put hanging on the edge of the toilet bowl.

Yeah. It's not exactly the end of the world if a dog drinks from the toilet bowl, but we're the type of dog owners who have a lot of physical contact with the dogs, so we'd definitely prefer them not to be dripping with toilet water.

Especially if the cat doesn't learn to flush like Charles Mingus' cat.

I’ve never had a cat that didn’t drink out of the toilet.