
there is a saying along the lines of "a dog and a bitch will never fight, a dog and a dog will sometimes fight, a bitch and a bitch will always fight". some would advise on a bitch pup but then you have to be careful of accidents. also, with a bitch your dog may become aggressive towards other males as he feels that the bitch belongs to him.
personally, our dogs have got on well together, 2 entire boys and touch wood, never had much of a squabble. has your boy had the snip, or is he all man... this could affect your decision?