Simple question;

1. can you breed change your wolf before they go to nest?

2. how will that affect the pups?

This is info from EA so take what I'm about to say with a grain of salt !! :D

1. Yes I believe you are able to change your wolfs breed before nesting. ◄THIS IS INACCURATE
2. The pups will not be affected by the change and will still be what the wolf was before the breed change for example if the wolf was a Lupin and you changed it into a Zerda then the puppies will still be Lupin since the wolf was already expecting before the breed change happened.

Again I'm not a mod so I cannot say for sure c:
@GwenniethePooh

You can't change it any more, at least not with breeds that change the cooldown time. I tried changing my starter wolves to Volmyrs after breeding them (didn't think it would effect the pups, but Vols are my fave breed) and it wouldn't work. Haven't tried it with common to common though.

you currently can't change breed while expecting/nesting. coat pattern changes can be applied, but what @Pearfect said is accurate for point 2, in that pups are based on what the parents were at time of breeding.