Recent aggressive behavior from my Basset hound

Question
My basset hound is 3 yrs old, very laid back, mellow, cool.  In the past she has always played well with any dog she comes in contact with, occassionally she would get an attitude & tell them to back off & she moves on.  She has never been mean or did anything that would make me think there would/could be a potential problem.  Recently I moved in with my boyfriend & he has a bully breed (mixed pit bull-terrier) who is extremely friendly (2 yrs old, almost).  The 2 of them have been hanging around each other since the pit bull terrier was a puppy, they have always gotten along & always played well together.  Then 2 days ago my basset hound attacked the (Jerzee) pit bull, she was not doing anything wrong Jerzee was chewing on a bone and my basset (Molly) attacked her & bit her 3 times in the neck drawing blood.  I was extremely upset, and didn't know what to do.  I figured something had to be wrong with her & I took her to the vet (she had not been feeling well for a couple days) he told me that i shouldnt worry about it that she was trying to tell the other dog she was in control, and she also had food poisoning.  Well since then she has been feeling better (or so it seems).  We went another night & they were fine, Jerzee was still a little scared of her & didn't want to be around her too much.  Then last night the same thing happened.  Again Jerzee was not doing anything wrong, just standing next to her kennel, when Molly came up & attacked again we had to break it up, Jerzee apparently realized she was bigger & stronger & it looked as though she may fight back this time.  This is not something I would ever expect out of my basset hound, I feel as though she thinks she is the 'dominant' dog, I don't know how to control this sudden change in her, its putting a huge strain on things.  What should I do, and why might she be acting like this after 3 yrs?  I appreciate any help you can give me. Thank you!

Answer
Your Basset is clearly attempting (and so far succeeding) in establishing dominance in her relationship with the Pit mix.  Two females often develop problem behaviors.  Your perception of what Jerzee is doing may not be accurate as reading dog body language is absolutely imperative in order to ascertain exactly why Molly is reacting.  If Jerzee is, in fact, doing "nothing", you have a rapidly developing problem which will develop into a full blown fight and the serious injury or death of one of your dogs.  Even if Jerzee is doing "something", this situation is about to escalate.

You need the intervention of a certified applied animal behaviorist (NOT A DOG TRAINER, huge difference.)  Both dogs need to be evaluated for temperament and observed together.  IF you intervene correctly NOW you CAN save this relationship.  This requires knowing which dog is temperamentally higher ranking than the other (and they may be so close this isn't possible to ascertain) and then instituting (with the use of positive reinforcement) a protocol for YOU to reward the appropriate body language of the subdominant dog toward the dominant dog.  This is a tricky business requiring expertise, and you need to be carefully taught.  Call the veterinary college in your geographical area and get referral to a professional (Ph.D., DVM, or certified in animal behavior).  Meanwhile, put a lightweight leash on BOTH dogs to wear indoors while you are at home; do NOT leave them alone together for any reason; do NOT attempt to get in the middle of any altercation (instead, use the leashes to get them apart or drag them away from one another by their hind legs but trust me you may be bitten in the process.)  An air horn can also be purchased; this will be such an aural shock that both dogs will stop fighting long enough for you to separate them.  What you DO NOT WANT is these dogs to begin fighting on sight.