sudden aggressive behaviour

Question
We have 2 dogs, one who is an elderly male 13 year old bearded Colie and the second is a 13 month female golden retriever. The male was nuetered years ago, the female has not yet been spayed.

When the female had just come out of her first heat she became aggressive 2 times with a sweet dog at doggie daycare.  A vet at the time suspected it was the result of hormones and that it would subside, which it did until recently.

Over the past 4 weeks our Golden has increasingly been "attacking", for lack of a better word, our bearded.  At first it appeared random, and shocked us as her temperment had been playful, passive.  As of the last 7 days the attacks have occurred one time per day.  The fights are always intervened by us pulling her off as the beardie does not see it coming and does not have the "gusto" to give it back.  The last 4 episodes the golden has locked or latched onto the beardie and would only let go when we applyed pressure to her throat.  Earlier this evening in attempint to break it up she bit me, although I do not think she was "after" me, I was trying to pull her off.

I called the vet this evening to push up the time for her spaying...thinking this could be the issue.  We are concerned about the cause.  All times of aggression have been around us humans.  

Answer
Yes the spaying might help,but it takes about three weeks for the hormones to calm down after that as well

If that doesn't help,you need to see a trainer as soon as you can,before it gets any worse

And sometimes,unfortunatly the only thing you can do is rehome her to a place without other dogs,as some dogs just can't live with other dogs