Scout - Vizsla/poodle mix
Soldier - border collie
Pyro - puli
Demoman - german spitz
Heavy - bullmastiff
Engineer - standard schnauzer
Medic - siberian husky
Sniper - greyhound
Spy - poodle

Miss pauling - chow chow
Administrator - saluki
Saxton hale - dalmatian
Merasmus - irish wolfhound

Animal characters like archimedes stay their original species, it’s just the human characters that are turned into dogs here.