i don't know if I'd take him to the vet so soon. When I pulled Ebony off a Pom a few months ago, she wasn't hurt at all but nevertheless sat there panting for a bit before calming down. Recently, it's been so d*mn hot up here I don't give it a second thought if she's panting after even a little exertion. I'd say if he was outdoors playing/fighting at a dog park in July, panting for a while afterward would be normal.
If it were me, I'd keep the cut clean (sounds like you've got that covered) and keep a close eye on the dog. Unless it's a very deep cut, it'll probably heal just fine on it's own. If your pup is still acting over-stressed or the cut gets inflamed in the next couple of days I'd say make an appointment to have a vet look at it.
~Marrow