Rabies is perhaps the very worst disease that most dog owners can imagine their dog being exposed to. Thankfully there are vaccinations that can be given to help the dog fight off the disease and be able to come through a rabies outbreak, even if they were directly exposed to the disease. One of the most problematic issues with rabies is that it is a zoonotic condition, which means it can be passed from species to species. Even if all domestic animals were to be vaccinated with rabies, wild animals would still be potential carriers of the disease, meaning it is highly unlikely to ever be completely eliminated. Not all dogs, cats or people bitten by an infected carrier animal will develop rabies and many healthy dogs will not become infected with the virus even without treatment pre bite.
Another concern with rabies is that it can also be passed to humans, although this is much less common than many people think. It is estimated that only 3 people die of rabies in the United States each year, but there are many other areas of the world where rabies continues to be a serious health risk.
There is a fairly predictable pattern of progression of rabies within the canine species. The first thing to keep in mind is that rabies is a virus that is passed by direct contact from the saliva of an infected animal to a healthy animal, typically through a bite. Dogs that are not bitten and not exposed to dogs or other animals that may potentially have the virus are not at risk of developing rabies. The most common wild animals to have rabies include bats, skunks, foxes and coyotes. Rats may also have rabies but they are generally not the major source of infection for dogs. The rabies virus cannot be carried in water, air or in fecal material. Even within the carcass of a dead animal with rabies the virus will die within 24 hours after the animal dies. The virus has to get almost immediately into the blood stream to stay viable and then travel to the nervous system where it begins to show its earliest signs and symptoms.
In the first stages after being bitten by an infected animal there is little in the way of symptoms or signs that the dog is harboring the deadly virus. Sometimes this period can last a few weeks or even months, making it extremely difficult for the owner to recall the exact contact and when the dog was exposed to the virus. During this period the virus is actually moving through the dog's body. It travels along the nerve tissue from the skin area of the wound through the body and up to the spinal cord. Depending on the location of the bite this can take a longer or shorter period of time. Once in the spinal cord the virus then moves up towards the brain and this process, like the migration to the spinal cord, can be fairly short or fairly long in duration. In most dogs the time from being bitten to actually showing symptoms is 3 to 8 weeks.
When this migration is happening the dog is not actually becoming sick, it is only after the virus starts to attack the brain that the earliest of symptoms will show. Amazingly enough during this period the dog is not a risk to any other animal or person, even if the dog does bite someone or some other animal. This is because the virus has not yet reached the salivary glands and cannot be transmitted. If the owners seeks treatment or vaccination for the dog for rabies during this period it is likely to increase the dog's chances of surviving.. Since rabies can only be diagnosed conclusively with an examination of brain tissue post-mortem, vets may recommend vaccinations start immediately after a bite or fight if the dog has not yet been vaccinated or is close to the booster date of the rabies vaccination.
Once the dog starts showing signs of the nervous disorders that characterize infection by the rabies virus he or she will have approximately 10 days to live. There is no treatment for rabies that is effective past this point so most dogs are isolated and then euthanized when it is ruled out that there are any other conditions causing the early symptoms.
The first noticeable stage is known as prodromal phase and is often completely missed by the owners. The dog will appear anxious and nervous, and will often hide or seek the most isolated area he or she can. They may have a complete temperament change where friendly dogs become shy and timid or aggressive and independent dogs become very friendly and affectionate. The dog may have fever spikes, may sleep more than usual and will show slight to moderate signs of anxiety and restlessness. Typically dogs will lick and chew at the sight of the bite, even if it is healed over. This stage will last two to three days for most dogs.
Different dogs will then respond differently in the next two phases. Typically dogs move from the prodromal phase into the furious phase, which is what most people associated with rabies. The dog is highly nervous and agitated, resulting with unreasonable level of aggression towards sounds, lights and movement. They become restless and pace all the time, rushing at enclosures and trying to bite at everything to get out. When enclosed in a cage they will chew at the wire and often injure themselves in their aggressive behavior. During this time the dog is no longer responding to owners and is a huge risk for infecting humans and other animals. As the phase progresses the dog will begin to have seizures and will eventually die within a maximum of 7 days.
Some dogs don't show as significant of a furious phase, rather they move into the paralytic phase. The head and neck are the first parts of the dog's body to become paralyzed, resulting in the open mouth and constant drooling or salivation. The dog will dehydrate quickly, further causing seizures and weakness. As the paralysis spreads the respiratory system stops functioning effectively. This results in labored, strangled sounding breathing and increased anxiety. The dog's chest will heave if he or she stops moving and the head is carried down with the legs braced. As this condition progresses over 2 to 4 days the dog will become increasingly weaker until he or she dies.