Its not personal against cats. Dogs are natural predators. They go after anything that tweaks their genetic memory about prey. Cats are just usually the most obviously available. When i take my dog out for a walk she goes after cats, other dogs, squirrels, birds, and cars... My cat and dog actually get along fine.
It's not that dogs hate cats. It's just that they want to be a cat's friend and either they try and claw and hiss, or they try and run away. If they claw and hiss it makes them evil, and the dog ends up wanting to eat it for it's rude behavior. If the cat runs it is considered like prey, why else would it run unless your suppose to eat? It must be prey and dinner. (Well that's according to animals) So they don't hate cats it's just that cats react bad to where the dog feels the need to eat/murder them.