Dogs have some amazing capabilities. Between being man's best friend and fulfilling numerous life defying jobs such as search and rescue, arsenal and bomb detection, seizure alert and assisting the handicapped, they truly are remarkable animals. It's little wonder why we feel like they can read our minds or understand the entire language we speak.
While dogs weren't born with the innate ability to literally read your mind (unless I missed the announcement), they were born with the ability to understand your intention and message based on your energy and body language. Dogs read body language like an open book. And they know how you are feeling based on the energy you project. Are you excited, sad, confident, hiding, afraid, overbearing? Your dog can tell.
Another fascinating aspect of their ability to "read our minds" is their natural response to specific energies we project according to whether it's a weak or strong energy in their world. For example, dogs target fear, because it is a weak energy and therefore needs to be corrected for harmony to exist. In the same way, they recognize healthy confidence and will yield to it knowing that it will bring health into the environment.
While your dog can understand and respond to what you are feeling, they can also change their behavioral patterns according to the communication you give them in energy/body language. If you are allowing them to perform behaviors that are ultimately out of line with their instincts that point towards balance, you are essentially creating disarray in their world. This is why dog's have behavior issues to begin with.
So remember that your dog will respond according to what you are feeling and expressing through your intention and nuances of body language when you work with them. You may be sending them mixed signals without realizing it, or they may be trying to clearly tell you something that you are not aware of.