Welcome to the family, hmm, what to watch for, lets see. I would watch for a young 13 week pup to grow up normal and be just like any other 13 week pup, but yours has character. You wil be amazed at how you won't even think about him being three legged as he grows, he will do just about everything the way he would with four. There might be a few things he won't do, but being this young he only knows this way, so it isn't like he will try to do things the way he would have before surgery if he was 6-7, Gus didn't limit himself, I had to make a few adjustments like make steps out of bales so he could still go up in the mow and check things out, and I had to put a block by the cow waterer so he could get his drink while checking out his girls, but since your not dealing with cancer, it should be life as usual, lucky you, you have just hit the lottery, tripawds have a something special that only tripawd owners know about, it's one of those things that you can descibe, but have to have one to feel, you won't be sorry, kudos to you for taking him in, Paws up, Spirit Gus and Dan