Not the best predictors of quakes...At least mine aren't. Or maybe they don't care.
About a couple or so years ago, we had a rather intense earthquake here in SF. I was in bed with my pets, and it's as if nothing happened. There were car alarms going off outside and my cats were still napping.
Another time an earthquake occurred, my cat was sitting on me and she dug her claws into my chest. I pushed her aside and little dots of blood seeped into my shirt.
The only things that bother my cats are really loud people and the vacuum cleaner.