fighting

Question
I have a cow dog, a boston terrier and pekapoo. they have been getting along for over a year. yet, a few weeks ago, i came home from work to find the pekapoo on the floor bloodied and ripped on both front legs and across chest. i immediately took her to vet at which point she had to be cleaned and medicated. it took 2 weeks of healing and 4 weeks of learning she could trust our other dogs. i have been keeping them separated up until 4-5 days ago, at which point, i had been allowing them to go outside at same time, and eat in the same room with me.  yesterday, i left my home, thinking (but not certain) that she was closed away in the back of the house, separate from the other two. yet, upon arriving home, my husband found the boston terrier with blood on her face and front legs and he began to look around and found the pekapoo under bar stool, chewed up again, but not as severe. the cow dog had blood on her face, jowels, mouth, and front legs. we found blood in multiple areas so we know that the pekapoo was trying to get away from them.  the boston terrier is in heat now..but not during last attack.  upon observing them, it appears that if another dog (esp male) gets close to the boston terrier, then the cow dog gets defensive. they three dogs involved in incident are female.  the pekapoo has been known to be defensive in her own right (growling around food), but should it have come to this.
my husband and I are at wits end to know what to do. we have a long history with all three dogs.

Answer
Becky -

I want you to do 2 things immediately.

One - take all of your dogs to the vet.  Sudden changes in behavior like this always require ruling out anything medical. I once had my dogs start picking on one of them and it turned out he was terminally ill.  It was a kind of wild behavior to drive the sick one out of the pack.  On the other hand, some dogs get more aggressive when they are ill.

Second. You simply must buy crates and crate your dogs whenever no one is home to supervise them.  The little dogs do not stand a chance against a cattle dog, and if one dog gets riled up, it quickly deteriorates into chaos.

You cannot put any of your dogs in danger, and leaving the 3 of them together is doing exactly that.

The last thing that I would recommend is getting a behaviorist or experienced trainer in to watch their interactions.  I cannot tell you what the causes are or the best way to resolve them since I cannot lay eyes on the situation. Someone experienced in reading dog posturing and body language should be able to put fresh eyes on the situation.

Good luck !  Let me know how you make out.

-Beth