Dogs go mad because of rabies, a viral infection. This virus infects the brain and the spinal cord. Rabies does infect not only dogs, it infects many other warm-blooded animals as well. Dogs are the only animal that can spread this deadly disease to man through bite. A bite causes the virus in the dog’s saliva to transfer to man. The symptoms of this disease appear four or six weeks after infection. The dog then, becomes quiet, gets fever and loses appetite. Next, it becomes excited and starts frothing at the mouth, starts growing and is likely to bite. Afterwards, within 3 to 5 days, the dog dies.