Overview 

Rabies is a viral disease that remains a significant public health concern.  

The virus is spread mainly through bites from an infected animal, causing neurologic disease and death. In the United States, bats, raccoons, skunks and foxes are the most common species to spread rabies. Cats are the most commonly infected domestic animal in the United States, but worldwide, dogs remain the most common source of rabies infections.  

Vaccination is crucial for prevention since there is currently no effective treatment for rabies in any species. 

Cause 

The rabies virus is most commonly spread when saliva from the infected animal makes contact with the blood of another animal, usually from a bite. All mammals are susceptible to rabies — including humans, cats, dogs, ferrets, livestock and wildlife.  

When an infected animal bites a non-infected animal, the transmitted virus replicates itself in the muscle around the bite site and then spreads to the nearby nerves. The virus then travels through the nerves to the central nervous system and brain. From there, it will move into other parts of the body, including the salivary glands, which are where the virus replicates and makes the animal infectious to others. Once in the brain and salivary glands, the animal begins to show clinical signs of rabies. 

The time between the initial bite and the time when clinical signs appear is referred to as the incubation period. The average incubation period for rabies is 3-12 weeks, but in some cases it could be several months — depending on the severity of the initial bite, the animal's age, number of nerves in the region, distance from the spinal cord and more. Although the incubation period for rabies can be prolonged, after symptoms are observed, animals usually die in less than a week.  

Clinical signs 

The most common signs of rabies are behavioral changes and paralysis, but other signs may include other neurologic behavioral changes or the following clinical signs: 

• Altered behavior  

• Nervousness 

• Aggression 

• Disorientation 

• Incoordination or staggering   

• Inability to swallow 

• Excessive drooling 

• Paralysis 

• Seizures 

Diagnosis 

There are no approved diagnostic tests for identifying rabies in living animals. Instead, rabies is diagnosed by microscopic testing of brain tissue in a deceased animal.  

Treatment 

There is no treatment or cure for rabies, so prevention via vaccination and education are crucial. Unlike for humans, there is no post-exposure prophylaxis for unvaccinated animals. In animal cases that are strongly suspected to be rabies, humane euthanasia is recommended, due to the fact that the disease is fatal for small mammals. It also presents a high risk of fatality for humans.  

Because the incubation period for rabies can be variable and prolonged in some cases, any wound in an unvaccinated animal that is suspected to be caused by a bite should be monitored with the guidance of a veterinarian. However, the exact rules for monitoring are complicated and can vary by state. 

If your vaccinated dog acquires a wound or has contact with wildlife such as bats, skunks, foxes or raccoons, your veterinarian will booster their rabies vaccine and recommend observation for 45 days for any signs of illness. 

Rabies is a reportable disease, so veterinarians and physicians must notify the local or state regulatory authorities if a dog bites a person. A 10-day quarantine of the animal that bit the person is observed in coordination with public health authorities, since this is more than the amount of time that it would take for a dog to succumb to the disease if their bite was a symptom of being already infected and capable of transmitting rabies. 

Outcome 

Rabies is a fatal disease. Most infected animals die within a week of demonstrating clinical signs, if not humanely euthanized.   

Zoonosis 

Rabies is zoonotic, meaning that humans can become infected if they are bitten by a rabid animal. Wildlife, especially bats, is the most common source of human exposure in the United States, but dogs are the most common source worldwide — which is important for people to remember when spending time in other countries that have a higher risk of exposure from infected dogs.  

If a person has been exposed to rabies, it can be deadly without urgent medical care. When received within a few days of a bite, post-exposure prophylaxis is a series of injections that is very effective at countering the infection. People who work in the animal field may receive pre-exposure vaccination. 

Prevention 

Because there is no effective treatment for rabies, prevention is the primary focus. Vaccinating dogs is the most critical step for rabies prevention in pets and in people.  

Rabies vaccines are incredibly effective. Puppies are generally vaccinated around 12 weeks of age, again when they are 1-year-old, and then every three years throughout their life. Rabies vaccines must be given by a veterinarian.  

Other preventive measures include avoiding interactions with dogs when traveling to countries where canine rabies is prevalent, preventing contact with wildlife such as skunks, foxes, bats, and raccoons, and seeking immediate medical care if possible exposure or a bite occurs.