I was cleaning the box and puppy back right leg got stuck under a 2x4 . He yelped and his paw was bleeding. Mom took him and cleaned it. I dont see anything cut maybe between the toes .I wiped up a little blood. Do I put anything on it ?

Mom is going to lick whatever you put on. Just watch it, it most likely will be OK. We had a 4 week old get a paw stuck under a door once. It limped 4 days but was fine after that. So sorry for you, we so love and worry about our 'babies'.