We don't speak the same language as our pets. But it's amazing what they can communicate with their actions if we really observe them.
Recently, a Great Dane/Shepherd mix kept running from his owner's home. He showed up at our shelter several times over the course of a few months. He desperately wanted exercise and wasn't neutered. Running away was the only way he could express his frustration. Ultimately, his owner grew weary of paying fines to redeem him, and this lucky dog ended up neutered and placed in a new home with an attentive owner.
Our pets' actions speak volumes. If your pet is behaving strangely, don't ignore it! He may be trying to tell you something important.
To find out more about animal behavior check out this page from the ASPCA.