Aggressive Female towards our Male 6 month old

Question
Hi there.
I have a 14 month old female and a 6 month old male, both Bull Terriers.  Just
recently the female has become quite aggressive towards our boy (who is so
placid) she will always start it, but only when he goes near her bed or chew,
she gives hardly any warning just flies at him. Its really been quite bad over
the past week, we think it could potentially be because she is due in season
any day - or do you think its because he is growing into a 'man' and she feels
more threatened.
She is normally a loving affectionate girl, and they play well together most of
the time.
We give them lots of love and necessary discipline.
Im really hoping that this is just because she is due in season, therefore will
pass.

Please advice.

Many Thanks.

Answer
"....necessary discipline", one wonders what that means.

I would remove all toys from these dogs at this time, except when they are apart, and make her "bed" inaccessible to either of them until night time.  I would also consider (very seriously) spaying this bitch twelve weeks after her cycle.  You wouldn't want to produce puppies from a bitch of this breed who is demonstrating possessive aggression.

At six months, your male is not developmentally at a place where he should pose a threat to your bitch, but I can't see that from here; it is possible her hormones are escalating her emotional response.  However, this behavior is unacceptable, and "discipline" isn't going to help (and can make things worse.)  You are unaware of what precipitates these episodes but there is fair warning, you're just not seeing it.  You need to learn about dog body language and observe these two closely; a subtle signal that you can learn may be all that's required to set her off.  Read Turid Rugaas' "Calming Signals"; also review books written by Patricia McConnell, Ph.D. to see which one fits your requirements in terms of managing this developing problem.  And the most important thing: get control of your dogs using BRAIN, not brawn.  Positive reinforcement training should be initiated with both dogs, separately.  The true "owner" of that bed is YOU; using a behavior trained with this method, you can make both dogs earn all interaction with you, their meals, etc. for the next six months.  Training a "go to" command can give you a signal the female will respond to instantly and happily for reward and praise and that can immediately short circuit any developing problem, which you will recognize having done your reading.  It sounds complicated, but none of it is.  Time consuming, yes, but ultimately putting psychological control of both dogs in your hands and averting what may develop into a situation that can't be remedied.