Rabies in Dogs. What is rabies in dogs? Rabies is a viral disease that affects the central nervous system of mammals, including dogs. The virus is typically spread through the saliva of infected animals, usually through bites or scratches. Rabies is a very serious disease that can be fatal if left untreated. In dogs, the symptoms of rabies can vary, but they typically include behavioral changes such as aggression or restlessness, as well as physical symptoms such as fever, muscle weakness, and s