Wait, how do you get Scratch to leave his dead friend?
You have to either use Speak with Animals or pass an Animal Handling check, show him you mean no harm and get him to sniff your hand. He will still stay with his friend, but probably on the next time you go to your camp he will have showed up after following your scent.
He will periodically find things and bring them to you at camp. One of them will be a ball that you can throw and he will fetch it for you.
Oh, and if you fail the animal handling check when you find him, you could have someone else in the party try it.