I like dogs, I don't like cats, but its not something I would become obsessed with or make part of a religion or something.
There could be alot of reasons why he hated dogs (he was nuts, a dog bit him, maybe a dog peed on his food, etc) but the whole love of cats and enemy of dogs thing is weird.
The only thing I have ever heard from a muslim about it, is they dogs are dirty, and thats pretty much it.
That bitch!!!!!