Apart from breed them obviously.

I only have one right now, (Update: I now have two, woo) but I still explore with her for money and food, ignoring the monsters mostly, only fighting them if they are in the way.

What do you do? Do you just breed from them and concentrate on lvling other pets?  Or do you explore with them still? Or do something else entirely? 

What about when the breedings run out?  I'll proably release into my reserve when that happens.

First of all, congrats on your 50s :)

Secondly, I still explore with some of them, although only my absolute favourites and then only rarely. Since the islands don't get bigger after level 41, I usually explore more with the pets in the range 41-49. Mostly I have them for the sake of having them. I do breed them but I haven't gotten to a point yet where my pets ran out of breedings. I'm honestly not sure what I would do if that happened though, since my reserve is (in theory) only for one of each colour pet (I messed up a few times and have some doubles, so I suppose I might as well just toss any level 50s in there that I don't need anymore.. xD), but usually I breed with them to get a certain offspring and then continue breeding those, so running out seems unlikely :)

Thank you!

I'm breeding for specific genes in some of them, hopefully I'll get what I want before breeds run out xD

Running out of breedings wasn't much of a problem before, but deviant colors definitely make that more likely. Even if you have a perfect breeding pair, on average it'll takes 100 breedings to get  a single double deviant. 

Anyway, level 50 pets? I keep most of them for quests... and nowadays for possible future exhibitions. The rest end up in the pound, or for sale. 

I generally don't explore with max level pets, since they don't get experience. Unless I'm trying to find forest alchemist for color changes.

I'm trying to get a sub-species of unicorn, a draft unicorn, with massive hooves, steel muscles and bones and thick skin/elemental resistance. Then when I breed two of them, use the Dusky Snow and Black Tip skins on them, because they look like draft unicorns. x3

Also, not related but...Snufkin!