I don’t know if its possible or not but it would be cool if some of the randomly generated houses in the towns could have dogs, zombie dogs or cats inside them, to simulate people’s pets they have left.
Sure, it’s possible. Poor critters though. 
KA101 brings cat food on all the house raids, just in case
…now that you mention cats, I’m curious why aren’t there zombie cats in CDDA?
Here kitty kitty kitty! Daddy has some tasty treats for you… oh. Nevermind that. Daddy has some shotgun shells for you.
They are too small, as implied in some of the lab notes. Cut-off for the zombified/stays dead boundary is somewhere between a medium dog and a large cat size.
makes note to self : pay more attention to lab notes…
This implies that the regular wandering dogs might all be toy breeds, chihuahuas, dachshunds, any small dogs… maybe not the case, but at somepoint during the aftermath, I bed it’d hold roughly true.
Or just any regular dog that, you know, managed to not die.
Toy breeds cannot survive without human involvement, by the way, so they’re right out.
I looked at that title and thought, “Yknow, I have a perfect story for this one.” Once upon a time I thought that it would be fun to try playing the scenario very bad day. It was indeed a very bad day because upon spawning I was beset by a pack of FLAMING ZOMBIE DOGS inside of the spawn house. I can hereby confirm animals do sometimes spawn in houses.