male and female jack russell terriers

Question
we have a 9 yr old male(sydney) and 4 yr old female(delilah). until recently,
delilah has been a very sweet submissive dog. the type of dog that rolls over
on her back anytime another dog approaches her. sydney and delilah have
been very close and loving to each other until recently. recently, anytime
sydney comes near her she viciously attacks him. sydney is the more
powerfull of the two yet delilah continues to attack him anyway. syd tries to
flee when he can though once he is threatened, he attacks back and we
cannot control either one of them. we're worried for a multitude of reasons
but mainly we do not want to see either one of them get hurt. food or treats
certainly instigate the problem so we ceased allowing them to eat and take
treats together. regardless of food, if syd simply walks by delilah, she begins
to attack him. we've tried separating her and putting her in her kennel though
this has only delayed the aggression. what should we do?

Answer
Without seeing them first hand, it's difficult to say what you should do, training-wise. I would first make an appointment at the vet's to have Delilah checked out. Tell the vet about her sudden aggressive outbursts, and make sure that she is first, healthy, before you take measures to train her to stop acting out.

I would recommend, if health issues are ruled out, consulting with a professional trainer that has experience dealing with dog-to-dog aggression. If she only behaves this way in your home, you will need to find a trainer that can come to your house to observe and make suggestions.