A dog's saliva can transmit the disease of rabies. By the way, so can the saliva of raccoons, bats, skunks and foxes.

If a dog or other animal actually has rabies, treatment has to start within 48 hours of the time of the bite. Nobody who was treated within 48 hours has ever died from rabies. Although few Americans are infected with rabies in any given year, precautions are required because an untreated case of rabies always ends in death.

Unless there is evidence of rabies, the normal procedure is for animal control to either take the biting dog into custody for 10 days or issue a written order to the dog owners to quarantine the dog at their home for that period of time. During quarantine the dog must not come into contact with other animals and its death must be reported. If it dies, its brain is tested for rabies. Violation of a quarantine order is a crime usually punishable by jail time. Concealing the dog to avoid a quarantine order also results in the same penalty.

If the dog does not die, the victim is presumed to be out of the woods and no treatment for rabies is administered. If it dies or the bite victim has rabies symptoms, however, treatment must commence immediately. Early symptoms of the disease include irritability, headache, fever and sometimes itching or pain at the site of the exposure. If untreated, rabies disease progresses within days to paralysis, spasms of the throat muscles, convulsions, delirium and death. The incubation period varies; it normally is 2 to 8 weeks, but in rare cases symptoms have appeared a year or more after exposure.

A dog owner who failed to obey laws requiring rabies vaccinations can be held liable for any resulting injuries and damages if his dog bites a person. If the victim suffered from rabies disease, the losses would be significant. Even if the victim simply had to undergo rabies treatment, the pain, inconvenience, and anxiety of worrying about the possibility of dying from rabies disease would result in a significant level of damages.

Additionally, violating a quarantine order or concealing a dog to prevent further investigation can also result in significant damages because of emotional distress on the part of the victim, as well as the cost, pain and suffering stemming from rabies treatment. 

For further information, see Rabies and Animal Control and Why They Quarantined Your Dog.