Find out who it belongs to and flat tell them you saw it chasing a deer.
It maybe they don't know it chases deer.
If they get all snoty about it then call dog wordon or just shoot it and forget it .
I don't shoot pets but have been told by dog wordon & game officer two diff. people that for them to do any thing they have to have it on camera so there can be no it's not my dog they don't have time to chase every call and about 1/2 of them they can't do a damn thing about as because they can't prove it was thier dog.
PS: I have been told by the game com. to shoot it and forget it end of story....