Big Paws Only Dog Forums

I just adopted a 3 year old Newfie and I was wondering if it is safe to have her shaved or at least trimmed.  We are in the midst of a very hot & dry Colorado summer and she seems to be soooo hot all the time.  And she's shedding like mad!  She was supposedly groomed before I got her but she has knots and matting around her ears.  I haven't attempted to brush out yet, but it seems like it might be impossible to get some of them out.

I just want to make sure it's safe before I get her cut.  Is there any factual info on the web anyone could recommend?