How to get a 'zombie pup'

On single player, go to Slough Creek. Find a den and mark your territory if you need to, then you will get pups. Name them if you want to!

Pick up a pup and walk/run away from the den. Keep walking until you find a stranger wolf (this is more likely to appear if you haven't marked your territory well enough). Walk to it whilst carrying the pup and beat the wolf.

Aftr the stranger wolf runs away, your pup will become a zombie!

Your pup isn't actually a zombie - it's just glitched! The reason why this "zombie" glitch occurs is that the code was put incorrectly, so the texture glitches. If you want your pup to be back to normal, restart the game ^^