Rabies in Dogs

The rabies virus released at the site of the bite from an infected animal latches on to the muscle cells. Incubation time varies - the virus can lie dormant for months or progress much faster, depending on the severity of the bite and the viral load transmitted through the bite. 

Symptoms start after the virus reaches the nerve cells and makes its way towards the brain. It is at this point that the disease becomes transmissible. It is important to note that a bite from a dog should be considered rabies-free if the dog is not dead within 10 days of the incident. This does not mean that you should not get the rabies treatment, however. It is important to do this especially if the dog is unknown and you do not know its vaccination history. 

The disease attacks the central nervous system and affects involuntary mechanisms. Death is caused by progressive paralysis; eventually, the intercostal muscles which control breathing are immobilized and the dog cannot survive.

As mentioned above, symptoms will appear once the virus has entered the neurons (nerve cells). Initially, in what is known as the prodromal stage, symptoms are suggestive of mild central nervous system (CNS) issues: 

• Spasm of the larynx (throat area).
• Reduced activity and reluctance to eat (inappetence in dogs).
• Lethargy in dogs
• Altered behaviour; for example, an outgoing dog may suddenly become shy or nervous.

This usually lasts for two-three days and quickly progresses to the next stage, known as the excitative stage or furious rabies. This includes the classical symptoms associated with rabies:

• Extreme changes in behaviour such as aggressiveness or uncharacteristic shyness.
• Hallucinations and no fear of other animals or humans.
• The dog may start eating stones or dirt (Pica in dogs).
• Hydrophobia, or fear of water - though this is usually a sign of rabies in humans, medical practitioners say this sign may also appear in dogs in the second stage of rabies infection.

Towards the end, the paralytic stage is reached, which includes:

• Foaming at the mouth as the larynx is paralyzed. 
• Tightening of the jaw 
• Paralysis and grand mal seizures 
• High fever
• Excessive salivation, as the dog is unable to swallow
• Ataxia or lack of coordination

If your dog is salivating excessively, do not open his/her mouth to investigate on your own - remember, rabies spreads through saliva. If your pet is infected, then he/she will likely experience behaviour changes as a sign of the disease - so he/she may not be their usual compliant, gentle self.

Take your pet to a doctor immediately, if your dog has been bitten by another animal. Even if your pet has received all the proper vaccinations, it's a good idea to play safe.

Rabies is a difficult disease to diagnose because symptoms are initially subtle and can suggest multiple differential diagnoses. Blood tests and imaging investigations cannot reveal the virus. 

A postmortem fluorescence antibody test can be conducted to ascertain if the virus was present. This is a public health measure that is meant to bolster culling or vaccination practices if rabies is discovered.

A diagnosis can be made if the answer to these questions is a "yes":

• If you live in a rabies endemic area, especially when the dog has been in contact with wildlife.
• The dog's symptoms are suggestive of the disease, then it can be assumed that it is a case of rabies.

If an unvaccinated dog is bitten by a rabid transmitter and begins to show symptoms, it cannot survive.

If the dog has been vaccinated, it must still be taken to the vet immediately for a booster shot. It will be kept in observation for 45 days to gauge stability. Dogs that are vaccinated and receive booster shots will most likely survive the bite. 

Subject to local laws, a dog that has been bitten by a suspected rabid animal and begins to show symptoms may be euthanized. If symptoms have not yet appeared, quarantining for an extended period of time, up to six months is recommended.

While rabies sounds like a death sentence, vaccines are considered highly effective and preventative.

Dogs usually receive a shot at the age of three months. This keeps them immune for a year, and then additional boosters maintain immunity for up to three years per dose. It is in the best interest of you and your dog to get your pet vaccinated.