What is rabies?
Rabies is a devastating viral disease that affects mammals, including dogs and humans, and is caused by the rabies virus. Once clinical signs of rabies occur, the disease is nearly always fatal.
Rabies virus occurs throughout the world, including North America, Central and South America, Asia, Africa, the Middle East, and some parts of Europe.
Some areas of the world are rabies-free, including Antarctica, Australia, Fiji, Finland, Iceland, the Republic of Ireland, Japan, New Zealand, Norway, Sweden, and the United Kingdom (England, Scotland, Wales, and Northern Ireland). Rabies-free countries rely on strict quarantine laws to keep the disease out and to stop the virus from getting into wildlife. This list is subject to change as a country’s rabies status is constantly under review.
How is rabies transmitted?
Rabies is transmitted when an infected animal bites another animal. Transmission by other means is rare. After the bite occurs, the rabies virus reproduces in tissues near the wound, then travels to the spinal cord before moving to the brain. After the virus enters the brain, it spreads to the salivary glands and organs. Once in the salivary glands, the virus can be shed in the saliva. Rabies virus does not survive long outside a mammal's body.
In North America, the skunk, raccoon, fox, and bat are important reservoirs for the virus, whereas in Europe, foxes are the main source of infection for people and other animals. In Asia, Africa, and Latin America, the main reservoir is not wildlife, but stray, free-roaming dogs. In these areas, human infection is more common.
How long does it take for signs to appear?
The time it takes for clinical signs appear (incubation period) can vary widely. In dogs, incubation can range from 3 to 24 weeks or longer. Death usually occurs within 10 days of the first signs. The speed at which clinical signs develop depends on the severity of the bite, the amount of virus introduced by the bite, and the site of infection (the nearer the bite is to the brain and spinal cord, the quicker the virus reaches the nervous tissue and causes symptoms).
What are the clinical signs of rabies?
Following a bite or scratch from a rabid animal, the disease progresses through three phases, although some dogs only exhibit signs of one or two phases.
- Prodromal Phase: In this initial phase, the dog undergoes a dramatic change in temperament. Quiet pets become agitated and active pets may become nervous or shy. This phase can last 2–3 days.
- Excitative Phase (furious rabies): Dogs often show no signs of this phase.
- The dog may become aggressive and highly excited.
- The dog may show an abnormal appetite—eating or chewing stones, earth, and rubbish (pica).
- Affected dogs may die in a violent seizure or they may progress to the paralytic phase.
- Paralytic Phase: Dogs commonly progress directly to this stage, skipping the excitative (furious) phase.
- The dog becomes weak and experiences progressive paralysis involving the limbs, distortion of the face, and difficulty swallowing.
- The dog may drool and foam at the mouth because the larynx is paralyzed.
- The dog may be unable to eat or drink. Owners often think the dog has something stuck in the mouth or throat.
- Ultimately, the dog becomes comatose and dies.
Note that hydrophobia (fear of water) is not a sign of rabies in dogs; it is a feature of human rabies.
How is rabies diagnosed?
Rabies can only be diagnosed by direct examination of the brain. It is not possible to diagnose this disease in a living animal. If there is a high suspicion that the animal has rabies, or if it has rabies symptoms and dies suddenly, your veterinarian may recommend submitting brain samples for testing. If there is any chance that a human has been exposed, submitting the animal’s brain samples may be mandatory.
Is it possible to survive a bite from a rabid animal?
There are isolated and poorly documented reports of dogs and people surviving. In some cases, there may be very little rabies virus present in the saliva when the rabid animal bites its victim, so the victim may not develop rabies.
There is an anti-rabies serum that can interrupt disease progression if it is used early, before symptoms appear. This antiserum contains specific immune antibodies to the virus.
The best way to prevent the progression of rabies is to administer a dose of rabies vaccine. The vaccine stimulates the bitten animal to develop its own neutralizing antibodies to the rabies virus. Without vaccination and rapid post-exposure treatment, the chances of survival are poor.
Is vaccination effective?
Vaccination is the cornerstone of rabies prevention. Vaccination promotes the production of antibodies but is only effective if given before the virus enters the nervous system. Modern rabies vaccines for dogs, cats, horses, and ferrets are extremely safe and effective.
Is post-bite vaccination used in exposed dogs?
If an unvaccinated dog is potentially exposed, and there is no human exposure, then the dog is given a rabies vaccination and placed in a strict quarantine (no direct contact with people) in accordance with your local public health agency’s guidelines.
If an unvaccinated dog is potentially exposed to rabies and it bites or scratches a human, your veterinarian may recommend against giving a vaccine. This is because a vaccine reaction can cause fever, lethargy, or stiffness and may make it look like the dog is developing signs of rabies when they aren’t actually infected. If there is a high probability of exposure, the safest policy is to euthanize the animal; the alternative is strict quarantine as noted above.
If the exposed dog has previously been vaccinated, then a booster vaccination is required, followed by a period of quarantine determined by local public health regulations and careful observation.
What is the treatment for rabies?
There is no treatment for a dog with rabies. If rabies is suspected, the dog must be kept in isolation and prevented from escaping or injuring someone. A dog shedding the rabies virus in the saliva will develop clinical signs within days, so a 10-day quarantine of the dog will be observed. A dog that is normal or healthy after 10 days is not considered contagious at the time of the bite.
Your veterinarian is required by law to notify the local, state, or provincial animal disease regulatory authorities. These authorities will determine the steps necessary to properly protect the public.
Can I be infected with rabies?
Yes, rabies is zoonotic (can be transmitted from an animal to a human), but it is only transmitted by the bite of a rabid animal. The virus is present in the saliva of the infected animal only for a limited time. If you are bitten by any animal, you should immediately wash the wound thoroughly with soap and water and seek the advice of a doctor. Any bite could mean rabies exposure.
Suspicious animals include stray or feral dogs or cats, any wild animal, and unvaccinated pets (including those not up to date on their vaccines), particularly if the animal is showing unusual behavior, such as lack of fear of people, excessive salivation, or aggression.
The World Health Organization (WHO) recommends that people who are bitten and have not previously been vaccinated for rabies should receive immunoglobulin (antibody) promptly, followed by a series of vaccines. People at high risk of rabies exposure should receive preventive human rabies vaccination (e.g., veterinary staff or those traveling to areas with high levels of endemic rabies).
Should my dog be vaccinated?
Yes, all dogs should be vaccinated between the ages of 12 and 16 weeks. Rabies vaccination is required by law in most states and provinces. Vaccinating dogs for rabies is important for your safety as well as your dog’s. The frequency of revaccination is dependent on state or provincial law. Your veterinarian will advise you on the appropriate re-vaccination intervals and can help you in obtaining any necessary licenses for your pet.
Is vaccination effective?
Vaccination is the cornerstone of rabies prevention. Vaccination helps an animal create antibodies, but it is only effective when given before the virus enters the nervous system. Modern rabies vaccines for dogs, cats, horses, and ferrets are extremely safe and effective.
Are there any side effects from rabies vaccination?
Rabies vaccines are safe and there is no risk of the vaccine causing rabies. Lumps or cancers (sarcomas) can form after any injection; if you see a lump, let your veterinarian know. As with all vaccines, an individual dog may show transient, mild side effects for a few days after vaccination, such as lethargy and low appetite. Call your veterinarian immediately if your dog shows more pronounced signs, such as difficulty breathing, as they may be allergic to one or more components of the vaccine.
