game bred dogs

The genetics will work the same. Too close though is dependent on the dogs involved. General rule of thumb is only to do those extremely tight breedings when you have two damn near perfect dogs. On top of that there needs to be a pedigree of proven dogs. You could have two litter mates that produce hogs for you even if you dropped em out in the middle of the atlantic, but if they are off of two cull quality dogs you've got a good shot at producing nothing but culls when bred together. So generally if your gonna breed tight its best off of two near perfect dogs with pedigrees full of near perfect dogs. You will still likely get some culls, but the ones that do turn out have the potential to go above and beyond their parents and will also have a strong ability to reproduce in their likeness.