HELP!!

Question
my sister and her boyfriend moved across country and they have a puppy bullmastiff that maybe full size and a three to four year old boxer. and both of these dogs fight constantly is there any way to control with a spray or something?

Answer
Are you sure they are fighting, or is it just rough play?  Sometimes it is hard to tell.  Fighting will have many quick,short snaps, the hair on the back up, and one trying to get away.  Growling will be low in the throat.  There will also be broken skin and fur pulled out.  Play will be grabbing and holding, may or may not be growling, and both will keep coming back for more.  

If they are really fighting, there may not be much that can be done except spay/neuter them if not already.  That, along with good leadership may help.  The key to most behavior problems is approaching things using the dog's natural instincts. Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog. Life is much easier if the 2 legged pack members outrank the 4 legged ones. You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat.

Otherwise, one of them may have to be rehomed.