Something like this happened to me, except it was the 4th step up, and he fell through the open stairs to the hardwood floor below. I was terrified, but the pooch totally got up and walking again like nothing happened. I didn't take him to the vet, but if he had shown any signs of pain, I definitely would have.
Just to confirm a restraint should only be attached to a good fitting harness - NEVER to a collar. Now go give your sweet baby lots of hugs and kisses
poor baby hope she's ok Franklin climbed on top of a pile of tan bark an tried to jump on grace's back an missed he limped for about 2 weeks an the vet said it wasn't broke just sprained an now everytime he plays hard he limps it sucks I just hope it goes away as he gets older

for being such caring bully pawrents.