My girlfriend and I have two dogs: Bodacious a 50#, 2 year old male lab/beagle mix and Bella a 20#, 1 year old Manchester Terrier/Min Pin Mix and my sister that lives with us and has a 2 year old male Bull Terrier named Diego that is about the same size as Bo but slightly shorter and heavier and a lot more muscular. Diego is fairly new to our house as my sister rescued him from a poor situation a couple months ago and we have had Bo since 10/1/2006. Bella is also fairly new as she was an emaciated stray we took in late in October of this year, but she really insn't involved with the problem I am having with the boys.
The problem is that Bo and Diego do not really get along very well. Whenever Diego comes close to Bo, he starts growling really low and sort of stalks him (stares him down, walks slow and stiff, etc). Diego is very playful and doesn't have a mean bone in his body, and I think he thinks that Bo's growling is an invitation to play because sometimes when Bo is growling, Diego will get behind him and kind of prod Bo in the side with his nose which makes Bo even more mad. Bo is definitely the aggressor.
When we come home from work or anything, the dogs of course are excited and happy to see us, and usually Diego and Bo will wrestle around and Bo growls the whole time and Bella will usually bark at Diego and bite at his back legs, but I don't see it as aggressive and more of a "Hey, I'm little but play with me too" kind of thing. During this time Bo will be growling somewhat playfully and will nibble on the back of Diego's neck while they run around and jump on each other and it has never sparked a large outburst. However, when there is a toy involved, things get nasty. Usually when Diego gets a toy, Bo will take it from him and then walk across the room, put it down and stand over it while growling and staring at Diego or he will lay down in front of where we keep the toys in order to guard all the toys from him and will growl when he gets close. Sometimes Bo will lunge at Diego if he gets too close to his precious toy and an all out brawl will start. Usually they are easily broken up by yelling and there isn't much damage to either dog besides a scratch or two, but on New Years Eve they got into it and Bo had ahold of Diego's face and neck and Diego had ahold of Bo's right leg. The yelling didn't stop the fight and I had to hold Bo down on the floor to stop him from trying to get at Diego, and once he calmed down he started yelping very loudly and I noticed several cuts on his leg and he couldn't walk on it. This required a $140 trip to the vet to get a staple in Bo's leg to close the wound, antibiotics, and some pain meds for a damaged pad on his paw. Diego's face and neck were pecked with puncture wounds from Bo's teeth but didn't require any medical attention.
Does anyone have any good ways to keep the dogs from fighting with each other? I really want to stop the growling from Bo anytime Diego comes near so we can avoid these scuffles.