dog bites groomers

Question
She bites when you come at her with anything to try and trim her hair to a resonable length. We have been to other groomers and she acted the same. She can take off muzzles and not hurt by groomers that we know about. She was a shelter dog before we adopted her.
-------------------------------------------
The text above is a follow-up to ...

-----Question-----
My dog bites at groomers and also at me. Is there any suggestions you would have that you may give me that might make this grooming period a little less stressfully on her me and the groomer please.
-----Answer-----
Holly,
  Does your dog try to bite when you touch a specific part
of his body or is it everywhere?
  Does your dog start acting scared, nervous, or just plain stressed when you get close to the groomer's shop?
Is this the only groomer you've ever tried or have you been
to others and she acted the same way?
  Has your dog ever been injured by a groomer that you know about, clipped the nails to short making them bleed ,
or maybe nicked by the shears or burnt by dryer?
 These are all questions that will aide me in giving you
the correct advice.
 Have you tried using a muzzle of some type while grooming
her? They help tremendously!
 Does your dog try to bite in a mean, threatening manor or
does she seem to be just trying to keep you away? Is she
normally affectionate?
 If you could answer these questions for me I will be able
to help you much easier.
Thank you. I'll be waiting to hear from you.
Doreen

Answer
Holly,
 Thank you for answering the questions I presented back to you.
 Unfortunately with an adopted dog you don't always know it's history as to how it was treated. But from what you tell me it does sound as if someone has harmed her in the past.
 But there are ways to combat this problem.
 If you have found a groomer that is willing to work with your dog and be patient enough to form a friendship so the dog doesn't feel threatened it will get better in time. Consistency of proper grooming with a caring groomer along with some other techniques should slowly change the way your dog reacts to getting groomed to a much better behavior.
 One way to start is to have your dog evaluated by a vet to see if she is capable of taking a small dose of a tranquilizer a half hour to forty five mins. before getting
groomed to calm her down safely so the groomer can get the
job done without over stressing your dog. This will also
allow your dog to learn to trust that the groomer you've
chosen for her isn't trying to hurt her.
You shouldn't have to use this method forever. I would
give it a try and see how it works first. If it seems to
help then you can use it a couple more times till the she
is comfortable and trusts your groomer.
If this doesn't work you can look around your area for a
groomer that specializes in tough to groom dogs. They
generally have safe non-harmful methods of grooming the dog
till the dog realizes it's not going to get hurt.
Sometimes a dog will never behave for the groomer due to
one reason or another. Most of the time it's due to abuse
by a groomer or an owner trying to groom the animal in a
vicious manor.
You can also help at home by brushing her while watching
TV and casually introducing a pair of scissors next to the
chair in her view. Then each time place them a little closer. Then without using them to cut her hair just glide
them over her body so she feels them and gets used to the
safe feeling that the scissors won't hurt her. After doing
this for awhile when you see she is comfortable you can
pretend to cut her hair by opening and closing the scissors
near her body so she can get use to the sound and again
this will re-affirm her that she won't be hurt and lesson
her fear of the sound they make which could be triggering
a memory. Then when she is okay with that try having her
groomed.
It might even be a good idea to do the exercises with her
for awhile before even trying a tranquilizer. Then the two
methods combined would greatly reduce her stress and she
could possibly be groomed without any problems. But these
will all have to be done with patience and love and the
knowledge that this will not be an over night transformation.
Don't give up and even if it ends up she continues hating
being groomed the last resort is to take her to a vet to be
groomed and they will do it while she is sedated so as to
avoid her getting hurt.
 I hope I have been of some help , good luck and God Bless!
Doreen