A few weeks ago we adopted a Staffy from the RSPCA. Everything went absolutely beautifully at first. Within the last week there have been a few fights.
Jethro - Red Heeler, 11 months old, de-sexed male
Abby - Mastiff x Ridgeback x Great Dane, 11 months old, de-sexed female
Kenzie - Staffy, roughly 6-9 months old, de-sexed female
Kenzie was the rescue from the RSPCA and we've had her for a few weeks now. We've had Abby & Jethro since they were 12 weeks old. Abby & Jethro have gone through obedience training and are continuing with training. We do have some issues to iron out still, Jethro jumps & barks more than we'd like him to and Abby is more responsive to me than my partner. Nothing major though. I've worked with Kenzie at home but she has not had formal training yet (pregnancy issues and the weather have thus far interfered with our dog training schedule).
Abby & Kenzie accept Jethro as the top dog. It seems that Kenzie has begun challenging Abby. There have been 3 fights, one of which was really more of a spat (growling, bitey faces, and lots of noise but no blood). The 2nd time Kenzie had two small patches of ripped fur around her cheeks with a little blood (the vet commented that this is common for how puppies play). The 3rd time, Kenzie's wounds from the 2nd fights were re-opened, she had a cut under one eye, and a puncture wound on her cheek from a bite and Abby had a tiny amount of blood as well. The 1st and 2nd fights were easy to split up and I separated the dogs. But in the 3rd fight both Abby & Kenzie completely ignored my voice (they're both usually responsive to me), I had to grab their collars and yank them apart. On all 3 occasions I've found Abby pinning Kenzie down on her back.
Here's what seems to be going on ....
Kenzie wants to play constantly, and she's playfully bitey. I think she pushes Abby to far and Abby tells her to back off but Kenzie doesn't listen. So then Abby has a go at Kenzie and Kenzie is frightened (Abby is 2-3 times the size of Kenzie) and fights back. Abby is also naturally more dominant than Kenzie.
What I've done about it:
1. I do everything (i.e. affection, food, letting outside) in the same order all the time: Jethro, Abby, Kenzie. I've talked to the vet about it and he said that it sounds like I'm doing everything right and he reinforced the importance of maintaining the pack hierarchy and not to unintentionally show favor to a dog lower in the pack.
2. Abby & Jethro are fine together un-supervised, Jethro & Kenzie are fine together unsupervised, but I'm nervous about leaving the 3 of them or Abby & Kenzie together unsupervised until this gets worked out. Right now I'm crating Abby & Kenzie next to each other to try to get them more comfortable together. I'm only letting the 3 of them or Abby & Kenzie out together when I'm in the backyard, and for less than an hour at a time (all 3 fights occurred when they were left outside together for more than an hour so I wonder if Abby just got too annoyed by Kenzie).
3. When all 3 dogs are outside I've been keeping Kenzie on a leash for most of the time and when she tries to do the bitey play with Abby or Jethro I give her a correction.
I've never had dogs fight before. I don't want to see any of our dogs hurt. I'm committed to working this out. Abby is not an aggressive dog at all and I really feel like Kenzie is provoking these fights. What's the best way to get the fighting to end so that all 3 dogs co-exist happily and harmoniously?