Cats/Dogs

At The House Of Night, cats share a special alliance with Vampyres. They cannot be chosen by someone, they choose their owner by themselves.

Zoey Redbird - Nala

Neferet - Skylar

Shaunee Cole and Erin Bates - Beelzebub

Damien Maslin - Cameron

Loren Blake - Wolverine

Darius - Nefertiti

Aphrodite LaFont - Maleficent (Previously called Princess Aurora)

Professor 'Dragon' Lankford - Shadowfax

Anastasia Lankford - Guinevere

James Stark and Jack Twist - Duchess

Also while I like the idea behind the cats, they should have given a proper explanation. Everything indicates they are supposed to be normal animals, but they are far smarter and intuitive than it is realistic.
Never made sense to me that they can foresee something like Kalonas return, but are just regular cats, which you can occupy virtually forever with a ball of string.

Is there ever an explanation why Stark has a dog instead of a cat?

Stark's dog? Not really other than the author wanting to mix things up a little. All the vampyres in the world, I'd expect some of them to be dog people.

I don't know about cats but I spend a lot of time with many dogs, some can be quite clever. Also we are dealing with a more fantastical world where vampyres and angels and other spiritual things exist. In that universe cats, like vampyres, have a special connection to Nyx so it's not a stretch to think the ones at the House of Night are not like cats in the real world.