One day I was home alone with my golden retriever. He suddenly ran for the door. I told him no one was home, then he became vicious. He was barking and biting at the air. I ran across the street and called my neighbor over to help. He just said to stay away from my dog. My dog calmed down and seemed normal again. The next night he started to thrash around again. My dog tried to pet him, thinking he was having a nightmare. The dog took a chunk out of my dad's hand. (at that point my dad was ready to shoot the dog and the poor dog just followed him around, as though he were apologizing) The final diagnosis was lung cancer. He was having siezures where he was not aware of his surroundings. Ironically, a week after my dog was put to sleep we got a call from the city stating that our dog did NOT have rabies. (they needed to do a test, since he bit my dad)
Fascinating. I am sorry about your poor dog.
When your dog starts petting people. It's always a good sign somethings wrong.