I recall the occasional dog appearing with witnesses in FK. There's the dog Alfred (or Albert?) in Beyond the Law, which belonged to the lady that gets questioned by Nick.
And the poodle in Unreality TV that belongs to the receptionist in the hotel where Nick, Schanke and the TV team make inquiries.

Nick himself probably gave up having pets as Lacroix usually ends up killing anything that Nick loves.

With vampires as pet owners there would also be the question of how well do pets fare when they never get to see daylight.