Wire-Haired Fox Terrier Behaviour

Question
I have a three year old dog, and in the last 12 months acquired a bitch puppy of the same breed. Until five weeks ago, they were good company for each other and for the family, however the bitch has recently come on heat and her behaviour has become more hostile and aggressive to the point of segregation due to constant fights and injuries. Despite this, both dogs do not show any of this above mentioned behaviour to humans it is just specific to each other. Her season has now finished but the behaviour towards him remains the same. I am concerned that this behaviour is going to continue, and is the separation prolonging the problem?
Many Thanks

Answer
Yes, I'd say the separation probably IS prolonging the problem. That's because dogs have a natural, genetic affinity and desire for the company of other dogs as well as for people. So keeping them separated isn't giving them a chance to find their way back to being in harmony.  However...! It sounds like they need a lot of help in learning how to do that and get past the unfortunate shift in their relationship. And since you mentioned actual injuries I'm assuming that there was some real, actual biting going on between them, not just a lot of snarling and posturing. So it's good to err on the side of caution.
Since the bitch is the "instigator," perhaps you could describe the kinds of things the male does that set her off, and whether she just goes straight into attack mode or gives off "warning" signals. Your descriptions might help me get a clearer picture of why and when she's attacking him. (I've seen something like this before so I have a pretty good idea about what might be causing her behavior, but would like more data before proceeding with more ideas on how to resolve this.) Of course, I'm assuming that once your male had been attacked a few times he began assuming a defensive, perhaps even a pre-emptive position with her. I'm wondering if you could describe his actual behaviors too, and what you think the particular stimuli are that set him off as well.

Thanks for your question. I hope you can help them work this out.

LCK