Observations:
Young adolescent male, older female. You can routinely see that Bella will passively stay out of Boot's range in regards to resources, especially after he has pushed her away or out of an area- off your lap. Remember even moving between you is a communication called "get away from my person". Boots routinely does this to Bella- it's normal, and he may be more willing to push the envelope because he's moving out of adolescence into adulthood.
Points to remember:
• Behavior changes over time
• Dogs are dogs
• Routine, daily or weekly fighting is abnormal and evidence of tension, stress or some unresolved or unmanaged conflict
• Aggression in situational
• Dogs fighting does NOT mean they will begin to attack kids or other dogs
When dogs do fight there isn't anything rational going on. So, you have dogs that are bred for stamina and bull baiting, some bully breeds have very little self control OR when they do fight they wouldn't necessarily puncture, but would do damage. I think the big concern is no only the location of the bites, but the amount of damage. It IS a concern, but there is no major avoidance behavior in the house that would be suggesting...I don't like him/her. There is no overt staring, body blocking or obvious attempts
Recommendations:
1. Don't lose your faith in your dogs. That being said, if you can't handle them being off leash together, they have no business being off leash if you are nervous or unsure.
• Manage- if a BASKET muzzle would have you feeling better or a Gentle Leader- USE IT. Better to manage and reduce the likelihood of fighting.
• Prepare- have Spray, a Shake can (soda can with pennies in it to toss at them if fighting), air horn, etc.
2. Leaders initiate, followers react
• Ask for basic behaviors like sitting to get access to food, to go out, to get toys, chewies, etc.
• Begin to then WAIT for your dogs to offer these behaviors, don't ask for them always
3. Boots
• With Boots outside, practice rewarding his already great recalls. Also practice calling him off if you get a bit uncomfortable rather than a stern "NO" or disrupting play. That way you are actually TRAINING the behavior you'd like to see instead of just interrupting that stuff all the time. Call him back to you- sit or down for 30 seconds- then tell him "okay go play" and release him back to play.
• Acclimate him to the Gentle Leader- put it on, treat him, take it off. Consider having it on him when off leash.
4. Enrichment for Boots: His destructive behavior is abnormal- and likely he's a bit anxious or stressed. A good measure of how stressed a dog is how much energy they are willing to invest in a behavior........ quite a bit of energy he's happy to invest.
• Feed from toys that dispense food- Tricky Treat Ball, Treat Stik, Kibble Nibble, Busy Buddy Toys
• 2-3 stuffed natural bones or kongs a day in the crate
• 3, 3 minute training sessions on the basics- name game, recalls
5. Resources
Continue to manage them around resources, I think it's fair to say that bones, toys, etc are something they will fight over. At this point, I'd prefer to have them chewing when confined than risk that for the time being.