I thought dogs liked to chase cats.
In these situations the dog is well aware of the double standard at play, The dog knows its not allowed to hurt the cat, its against the house rules.
It also knows the cat doesnt give a damn about house rules and will put the claw in as soon as it has a chance.
The dog is smart enough to know cats are evil and cant be trusted, and the cat is smart enough to know the dog cant do a thing about it