Rabies is a disease nearly everyone has heard of, especially if you share your life with pets. But how much do you really know about it?
As recently as 50 years ago, the most common rabies carriers were pet dogs. Back then, most dogs roamed loose and were more likely to come into contact with infected wild animals, and rabies vaccines for pets weren’t yet commonly used in veterinary medicine.
Today, more than 90% of rabies cases are found in wildlife – mainly raccoons, bats, skunks, foxes, and coyotes – rather than in domesticated pets. Raccoons are currently the #1 carriers of rabies in the United States (which considering their tendency to hang around suburban areas where dogs and cats are prevalent, raiding trash cans and outdoor pet food dishes, this can be somewhat concerning!)
Fortunately, rabies cases here in the U.S. are relatively rare. According to the American Humane Association, human cases of rabies average only about 2 per year, with cases in pets estimated between 400-500 per year.
Although rare in developed countries, rabies is a very serious disease worldwide. According to the Avicenna Journal of Medical Biotechnology, “rabies has the dubious distinction of having the highest case fatality rate of all known infectious diseases.”
Here’s why rabies is definitely not something to be taken lightly.
What Causes Rabies, And Why Is It So Dangerous?
Rabies is caused by a virus that viciously attacks the brain and central nervous system in warm-blooded mammals. It’s almost always transmitted in saliva through the bite of an infected animal. Once an animal (or human) is bitten, the virus enters the body and begins replicating itself in muscle cells. From there, it travels to the closest nerves, and hitches a ride through fluid in the nerves to the brain. Once in the brain, the rabies virus spreads throughout the entire body, including the animal’s salivary glands so it can be transmitted to another animal once again through a bite.
The rabies virus usually takes anywhere from 3 to 8 weeks to fully develop (although in rare cases it can take several months). Once symptoms appear, rabies progresses very quickly. During this time, the infected animal is considered contagious to humans and other animals.
Rabies is almost always fatal, causing death within days of the onset of clinical signs.
The rabies virus can also be transmitted when saliva containing the virus comes into contact with a cut or open wound in the skin. In these cases, the victim doesn’t have to be bitten to be exposed. During my veterinary technician rotation at Ohio State, I remember a professor telling us about a veterinarian who, unbeknownst to him, treated a cow that had been exposed to rabies. The vet had put his ungloved hands in the cow’s mouth to administer medication, then flew to Mexico the next day for vacation. Two days later, the cow came down with rabies, and the veterinarian’s colleagues desperately tried to find him for several days before finally locating him and bringing him back to the U.S. immediately to undergo preventive treatment for rabies exposure.
There is one other way that rabies can be transmitted without a bite wound. The virus can become aerosolized through urine and feces in caves containing large numbers of infected bats. If an animal or human breathes in the secretions, in very rare cases they can become infected.
The 3 Phases Of Rabies Infection
After an animal is exposed to rabies, there are 3 distinct phases of the disease.
The Prodromal Phase
This is the early stage of rabies, when the virus is reproducing in muscle and tissue. Dogs and cats may show only mild symptoms, or none at all. In dogs, this stage typically lasts for 2 or 3 days, while cats seem to progress more quickly.
During this time, the most apparent symptom is a change in behavior. Friendly animals may become fearful, shy, or more aggressive, and otherwise fearful or aggressive animals can become overly-friendly. The animal may become more nervous and anxious, and may run a fever. After the prodromal phase, the animal can progress to either the “furious” phase, the paralytic phase, or a combination of both.
The “Furious” Phase
During the furious phase, which can last from 1 to 7 days, the rabies virus enters the nerves, travels to the brain, and spreads to other places in the body that contain large numbers of nerves, including the salivary glands. During this stage, the infected animal is extremely sensitive to light and sound. They can become aggressive, attacking people, other animals, even inanimate objects. Some may become agitated and restless, wandering aimlessly for hours at a time. Eventually, these animals become ataxic (weak and wobbly), and may develop seizures, leading to death.
The Paralytic, or “Dumb”, Phase
Most animals develop this phase directly after the prodromal period, but they can also experience the furious phase first. During this stage, the nerves of the head and throat become paralyzed, causing the animal to drool and be unable to close their mouths or swallow. Once in the paralytic phase of rabies, the animal becomes weak and paralysis becomes worse and worse, until death is finally caused by respiratory arrest.
It’s important to remember that not all animals infected with rabies exhibit these symptoms. Some can progress through these stages and die without showing any major symptoms at all.
Other Symptoms Of Rabies
Other less common symptoms of rabies can include:
- Not eating
- Pawing at the mouth
- Constant biting or licking at the site of the initial bite wound (almost like the wound “stings”)
- Pica (eating non-food objects)
- Change in the sound or tone of the animal’s bark or meow
- Choking behavior
- Hydrophobia, an aversion to drinking water (most likely due to difficulty swallowing)
Diagnosing And Treating Rabies
Here’s the really tragic thing about rabies: no accurate test exists to diagnose rabies in live animals. The only way to positively confirm a rabies diagnosis is to euthanize the animal and examine its brain tissue using a direct fluorescent antibody test. Blood tests have not been proven to be reliable, and since rabies is such a serious disease, the test needs to be as accurate as possible.
Adding to the tragedy is the fact that there is no treatment or cure for rabies once symptoms appear. Rabies is almost always fatal for unvaccinated animals, with death usually occurring within 7 to 10 days after the onset of initial symptoms. Therefore, most unvaccinated dogs or cats who are suspected of having rabies are usually immediately humanely euthanized.
However, for dogs or cats who are suspected of having been exposed to rabies AND have been vaccinated at least once against the virus (even if they are not current on their rabies vaccination), these pets can be revaccinated immediately and closely observed for 45 days. This new guidance comes from the American Veterinary Medical Association, and replaces the old practice of either quarantining an animal for a period of up to 6 months, or immediately euthanizing it.
Preventing Rabies In Your Pets
Rabies is virtually 100% preventable with one very simple thing: a rabies vaccine.
Rabies vaccines are usually given to puppies and kittens at 16 weeks of age. A booster is recommended one year later. When vaccinating your dog or cat against rabies, always ask for a 3-year rabies vaccine (rather than a 1-year vaccine). If possible, ask your vet to use only a non-adjuvanted rabies vaccine, such as Merial’s PureVax rabies vaccine. (For more information on how to safely vaccinate your pets, please read my article “Vaccinations: Too Much Of A Good Thing?”)
Most states have laws that require rabies vaccinations for dogs and cats. By law, these vaccines must be administered under the direct supervision of a veterinarian, so although it’s possible to purchase the vaccine yourself through some online suppliers, don’t do it. If your dog or cat is exposed to rabies and they have not received the vaccination from a veterinarian, most states will not accept it as valid.
Protecting Your Pets (And Yourself) Against Rabies
There are many ways you can reduce the risk of rabies exposure to yourself and your pets:
- Avoid direct contact with wildlife, whether dead or alive. If you find an injured wild animal, don’t touch it. It’s best to call in the experts such as your local animal control agency or wildlife rescue group.
- Don’t keep a wild animal as a pet, as these animals cannot be vaccinated against rabies.
- Don’t let your dog or cat roam free. This eliminates the chance that they can be exposed to, or bitten by, rabid animals.
- Feed your pets indoors only. Don’t leave food outside that can attract stray cats, dogs, raccoons, skunks, or other wildlife to your yard.
- Avoid any wild animals that seem overly friendly or aggressive, or are displaying odd or unnatural behaviors.
- Keep lids on your trash cans, and don’t leave garbage bags outside where they can attract other animals.
- Know your state’s rabies laws and keep your pets’ rabies vaccinations up to date. If you have an elderly pet, or have concerns about the over-administration of vaccinations, talk with your vet about your options. Some states will allow you to obtain a rabies vaccine exemption as long as you have your pet’s blood tested to prove he or she is still protected against rabies. Your vet can tell you more about this.
- If you suspect your pet has been bitten by any unknown animal (either wild or domestic), call your veterinarian immediately.
- Teach your children to avoid strange or unfamiliar animals.
A World Without Rabies
Rabies may be rare in our part of the world, but it’s a serious disease that should never be taken lightly. This deadly disease even has its own annual “World Rabies Day” to help educate the public on rabies prevention.
This year’s World Rabies Day theme was “Educate. Vaccinate. Eliminate.” I can’t think of a better way to summarize the importance of both vaccinating our pets against rabies, and helping to educate ourselves on how to prevent it – doing our part to contribute toward the World Health Organization’s goal of zero deaths from rabies by the year 2030.
Have you ever seen, or been exposed to, a pet or wild animal with rabies? Are your pets vaccinated against rabies? Please share your thoughts with us in the comments below!