I don't have max wolves yet, but I've noticed that it takes a while for Pageant to load in all my wolves, and there's a lot of scrolling to then be done. It seemed like it would be nice if I could just mark my wolves as unable to participate, so I won't have to scroll through wolves that I'll never put in the Pageant.
Similarly, I have a lot of breedable wolves, but don't want to ever breed some of them. If I could mark them as unavailable for breeding, it'd simplify my life. This could also be used to prevent the stress people have over accidental breedings.
Note: Not fixed/spayed/neutered, they're entirely intact, just marked as unavailable in your den only. If you sell/trade the wolf, that ineligibility doesn't stay. It can also be switched on/off at any time.
Marking them as unable to participate in Hunting might be similarly useful. Maybe Campaign, too. Most people probably don't change Miner and Fisher enough for it to be relevant, but if it's easier to include that.
I think that covers everything. It'd probably be a little annoying to implement, I'd think, but not too bad, and would probably be greatly appreciated (especially for breeding!).