Yesterday (September 28th) was World Rabies Day, and Rabies Awareness Month (held in October) is just around the corner. What better time than now to educate dog and cat owners about the dangers of Rabies?!
The Meowing Vet teaches pet owners about the horrors of Rabies and how to properly protect dogs and cats through vaccination. Read more…
What is Rabies?
Rabies, transmitted primarily through the bite wounds of mammals infected with the Rabies virus, is an incurable disease affecting the nervous system and causing death in as early as 2 weeks following exposure. Not only are dogs and cats (and other animals) at risk, but Rabies is also a zoonotic disease, meaning it is transmissible to humans. Millions of people and animals are at risk around the globe. However, with certain precautions, Rabies is also fully preventable.
The Rabies virus is of the Rhabdoviridae family of the genus Lyssavirus. Different strains of the Rabies virus exist: a dog, bat, raccoon, fox, and skunk strain. Certain vial strains may be more common in different wild animal carriers in various geographic regions. However, all pose a risk to dogs, cats, and humans. As mentioned, most cases are transmitted via bite wounds. However, exposure to any saliva or tissue or fluid of the nervous system (such as cerebral spinal fluid) that is infected with the Rabies virus can allow transmission. Contact through any break in the skin and potentially through the conjuctival or mucus membranes (such as of the airway passages) can put you and your pet at risk.
Though not every nation has the Rabies virus, isolated outbreaks of other Lyssavirus agents have been reported. For instance, some bats in Australia have the Australian Bat Lyssavirus, and Scotland has also had reports of a European Bat Lyssavirus-1 strain. In some circumstances, human exposure to these Lyssavirus agents can be deadly.
The map below depicts nations that are at highest threat of human Rabies exposure. Please note that while North America is deemed a “low risk” nation, this is largely due to strict Rabies vaccination protocols for dogs and cats that greatly reduce the threat of Rabies outbreaks both among humans and pets. Without such stringent vaccine rules, the human Rabies risk would be much greater in North America. Thus, vaccines are imperative in such regions.
Map courtesy of the World Health Organization (WHO), International Travel and Health, 2013.
Some of this article’s information may not be applicable to every pet owner, predominately if you live in a region of the world where Rabies is not a threat. Though by no means an exhaustive list, the following regions are currently deemed Rabies-free jurisdictions (i.e. have had no reported endemic cases of Rabies since 2009).
Geographic Locations That Are Free of Rabies
- The U.S. state of Hawaii
- Many islands in the Caribbean, including the Bahamas, Bermuda, the Virgin Islands, the Cayman Islands, Jamaica, Barbados, Aruba, the Galapagos Islands, Easter Island, Saint Kitts and Nevis, Saint Lucia, Trinidad and Tobago, Turks and Caicos
- Many nations in Central and South America, such as Costa Rica, Argentina, Chile, Uruguay
- A large number of European countries: Ireland, U.K., most of Spain, Portugal, France, Monaco, Italy, Belgium, Liechtenstein, Luxembourg, Germany, Austria, Switzerland, Czech Republic, Denmark, Finland, Estonia, Latvia, the Netherlands, most of Norway, Sweden
- The Canary Islands and several other islands off continental Africa
- Several regions of Asia: Hong Kong, Japan, the Maldives, Singapore
- Australia, New Zealand, and many other islands in Oceania
- Antarctica
To prevent Rabies from entering the above locations, these regions are extremely vigilant with their import rules regarding animals travelling into such areas.
You can learn more about the global Rabies risk through information from the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO).
How dangerous is Rabies?
Rabid dog bites are the biggest cause of human Rabies globally (though bat exposure is most common in the U.S.).
Depending on your geographic location, the threat of Rabies exposure may be extremely high. The World Health Organization (WHO) estimates that nearly 55,000 people die of Rabies worldwide each year, with 95% of these fatalities occurring in Asia and Africa. Once the clinical signs of Rabies have developed (see below for details), it is incurable with nearly 100% case mortality. This means that if a human is exposed to the Rabies virus, and rather than receiving post-exposure prophylaxis (PEP), the individual instead goes on to develop clinical signs of the disease due to spread to the central nervous system, that person will inevitably die of Rabies. And a horrible death it is — disorientation, mania, convulsions — and often alone in isolation to prevent spreading the disease to other people. The same fate is true for animals that acquire Rabies: death is sure to follow.
That being said, people and animals (including dogs and cats that are not vaccinated against Rabies) are at risk of developing Rabies infection if they are exposed to rabid pets or wild animals in territories where the virus is endemic.
Exposure to the saliva of rabid animals via bite wounds is the most common way that Rabies is transmitted to humans.
How can I and my pet contract the Rabies virus?
Nearly all (i.e. 99%) of human Rabies cases occur secondary to rabid dog bites (with the exception of the United States, where exposure to bats is the main Rabies threat to people). With human Rabies cases, these people fail to receive proper post-exposure prophylaxis (PEP), which can prevent clinical signs of the disease from occurring, sparing the lives of exposed individuals. Oftentimes, limited access to medical care or not having the monetary means to pay for proper post-exposure therapy is the main issue behind human Rabies fatalities, primarily since the majority of such cases occur in areas of Asia and Africa where resources are scarce and poverty is common. Consider donating to a reputable veterinary or human medical organization which strives to provide proper care for people in under-served areas with high Rabies exposure risks, for instance Doctors Without Borders / Medecins Sans Frontieres.
Roughly 40% of human individuals bitten by an animal suspected of being rabid are children (under 15 years of age). Teaching your children how to safely approach and handle animals (especially dogs) is imperative in reducing dog bites and potential Rabies exposure. Pet overpopulation control through spay and neuter programs is also valuable by reducing the number of stray dogs and cats that could serve as possible Rabies vectors.
Because Rabies can also be spread by wildlife, it is safest to assume that any wild mammal (especially if it is exhibiting abnormal neurological behavior) is rabid until proven otherwise. Therefore, avoid contact with certain Rabies vectors (a.k.a. carriers or transmitters), and report bites or exposure to the saliva of these wild animals to your local authorities. Additionally, if you wake up from a sleep to discover that a bat has entered your home, call your animal control office and physician. The bat may have bitten you in your sleep without your knowledge, possibly exposing you to Rabies. Similarly, take precautions when cleaning up an area where bats have been nesting (such as an attic). Though the risk is much lower when compared to sustaining a bite from a rabid animal, aerosolized bat saliva can potentially be inhaled and penetrate the mucus membranes inside your nasal passages, possibly exposing you to the Rabies virus.
Below is a list of the most common Rabies vectors in North America: bats, raccoons, foxes, skunks, and even groundhogs (also called gophers). Rabies has also been reported in other animals such as bobcats, bear, and beavers; other mammals are also theoretical vectors. The riskiest vector species may vary depending on your country and specific region. Keep in mind that not all vectors may be showing signs of Rabies when they are infectious to you and your pets.
Top Wildlife Vectors of Rabies in North America
Bats
Raccoons
Foxes
Skunks
Groundhogs (Gophers)
Don’t fear the American opossum! Possums are absolutely amazing creatures, yet many people unfairly judge these animals, deeming them ugly, dirty, or frightening vermin. This couldn’t be further from the truth. These marsupials (the only marsupial species in North America) not only eat insects and pests that could otherwise harm humans and pets, but their immune systems are incredible. Possums are quite resistant to many infections, including Rabies! Rabies infection is extremely rare in the American opossum, so don’t be overly worried that these spectacular animals are a threat to your family’s or your pet’s health. They are not deemed a significant Rabies vector.
Possums are extremely UNlikely to carry Rabies.
What happens if a human or animal develops Rabies?
After a human or pet is bitten by a rabid animal, the Rabies virus enters the bite wound through the rabid animal’s saliva. If your pet has been properly vaccinated against Rabies, his or her immune system will kick in at this stage, sending out antibodies to fight off the invading Rabies viral particles at the bite location, preventing them from spreading further and causing an infection and death. Unvaccinated pets and humans are not so lucky. Once the bite occurs, the virus migrates from the skin wound to nearby peripheral nerves. This pathway of nerves eventually connect to the spinal cord and brain, serving as a roadway for the virus to travel. Once the virus has invaded the central nervous system (the brain and spinal cord), the clinical signs will develop within 10 days, lasting for 1-7 days before death inescapably occurs. When the central nervous system is affected, the virus also travels to the infected person or animal’s salivary glands, waiting to be a source of infection to another mammal that is the recipient of a bite wound or other exposed to the infected saliva.
The time between the initial exposure (for example, a bite) and the onset of clinical signs is known as the incubation period. The incubation period of Rabies in humans is typically 1-3 months but can last as little as 2 weeks or persist up to a year in some cases. Why the time difference? The discrepancy is partially linked to the distance that the Rabies virus has to travel from the initial bite wound to the brain. For instance, a bite sustained on the foot would result in a longer incubation period than would a bite to the head or neck.
There are two main clinical forms that a Rabies infection may take: “dumb form” (also termed “paralytic form”) or “furious form”. Dogs and cats are most likely to experience “furious form” while horses and livestock tend to exhibit “dumb form”. Humans may display either or a combination of signs. While I was in veterinary school, we were requested to watch footage of children in India who were suffering the devastating end-stage effects of Rabies. Such scenes were some of the most harrowing that I have ever witnessed, yet the point was driven home: Educate as many individuals as possible to prevent the devastating consequences of Rabies infection in pets and people.
Clinical Signs of Rabies in Humans and Animals
Nondescript signs
- Fever
- Headache (in humans)
- Pain and abnormal nerve sensations (paraesthesia) at site of the bite wound
- Uncoordinated movements
“Furious Form”
- Anxiety
- Hyperactivity
- Photophobia (“fear of light”): experiencing pain when exposed to bright lights
- Hydrophobia (“fear of water”): Sometimes, a rabid individual may act extremely agitated around water. This may be secondary to loss of the ability to swallow liquids (and food) due to uncontrollable nerve spasms in the throat, resulting in extreme frustration due to unquenchable thirst. Failure of the ability to swallow is also responsible for…
- Drooling or excessive salivation (i.e. “foaming at the mouth”): This occurs due to the throat spasms as explained above as well as viral infection of the salivary glands.
- Violent outbursts and aggressive behavior
“Dumb Form”
- Somnolence (sleepiness)
- Depression
- Aimless wandering behavior
- Paralysis
The above signs precede the following:
- Convulsions
- Coma
- Death: usually secondary to cardiopulmonary arrest — i.e. cessation of normal movement of the heart and lungs
The majority of human Rabies cases occur in Asia and Africa. 40% of suspected rabid dog bites involve children.
How is Rabies diagnosed? Is it treatable?
Diagnosing Rabies can be a difficult feat. You may have heard that to diagnose Rabies, your pet must be euthanized and its head cut off to be sent to a state laboratory for its brain to be tested for evidence of Rabies. This is a blunt description but overall an accurate one.
The Rabies virus lives in the nervous system, not the blood, so bloodwork is not typically useful in detecting Rabies. Instead, brain tissue must be obtained during a post-mortem exam (i.e. an autopsy, or necropsy) and submitted for analysis in a specialty lab. Tests include the direct fluorescence antibody test, microscopic examination for the presence of Negri bodies (special features in the brain secondary to Rabies virus infection), the Rabies tissue culture inoculation test, and the mouse inoculation (i.e. experimentally exposing a laboratory mouse to saliva of the animal in question to see if the mouse also develops signs of Rabies — of questionable ethics). Special tests for suspected human Rabies cases include RT-PCR and serology.
Unfortunately, sampling brain tissue is not reasonably possible in live animals. Therefore, a living animal (pet or wildlife) suspected to be rabid or exposed to a rabid animal must be quarantined for observation (read more below) or euthanized. Obviously, the latter is not ideal. So may the threat of required euthanasia in the face of possible Rabies exposure urge you to maintain your dog or cat’s Rabies vaccination status if you live in a country where Rabies is present.
Unfortunately, Rabies is not treatable once clinical signs have developed (i.e. once the virus has spread to the central nervous system). Death is inevitable in all such cases. Thus, prevention is key.
A bite from a rabid dog is the #1 cause of human Rabies worldwide. Human Rabies accounts for 55,000 human deaths annually.
The Rabies Vaccine for Dogs and Cats
The Rabies vaccine is legally required by most U.S. states as well as in other areas of the world where Rabies is of concern. Proper Rabies vaccination and documented proof provided by your veterinarian are also necessary if your pet is travelling via plane or commercial boat. If your pet will be travelling from a region that has Rabies to a Rabies-free jurisdiction, a mandatory quarantine period is also likely be required. Quarantine allows for observation of your pet for the potential onset of clinical signs of Rabies before your pet can be released into the Rabies-free territory and exposed to other animals and people.
As stated, in the United States, all dogs and cats are legally required to be vaccinated against Rabies. In special circumstances, other animals (such as ferrets, horses, and livestock) are also recommended or required to receive the Rabies vaccine. Dogs and cats are vaccinated around 4 months of age, 1 year later, and then every 3 years in most cases (although some newer vaccines require annual boosters for cats, such as the PUREVAX™ vaccine type by Merial). Only veterinarians should administer the vaccine (injected under the skin, or subcutaneously, in the right rear leg). Pet owners should register for a Rabies license with their local governing body as well as an identification tag to be displayed on their pet’s collar.
Regularly boostering your dog or cat’s vaccine is vitally important to keep their immune system “amped up” with a protective level of antibodies against the Rabies virus, preventing the disease from spreading to the nervous system if your pet is bitten by a rabid animal. Even if your pet is strictly indoors, Rabies vaccination is mandatory in the U.S. There is always the potential risk for your pet to escape outdoors, sustaining a bite from a wild or stray animal that may be carrying Rabies. Alternatively, a wild rabid animal (such as a bat) could enter your home, threatening your unvaccinated pet’s health. Keep in mind that it takes nearly a month for your pet’s immune system to produce enough antibodies to be amount a protective level, so a vaccinated animal is not considered to be protected for 28 days following an initial Rabies vaccine administration.
Don’t believe all the hype you may hear about the potential deleterious effects concerning the volume of the Rabies vaccine being more harmful to smaller pets vs. larger pets. It is true that for most formulations, the same volume (1 mL) of the Rabies vaccine is administered to dogs and cats of all sizes: one dose fits all. (Some newer vaccine formulations may be only 0.5 mL.) Owners of small breed dogs and cats may flinch at the thought that their tiny pet is receiving the same dose that a giant breed dog also receives. However, this is necessary, and the volume of the vaccine by itself does not pose an additional health risk to smaller animals.
Why? Dogs and cats may have different sized bodies, but their immune system is roughly the “same size” in a manner of speaking. The immune system of most living beings requires a large enough inoculum (i.e. a high enough number of foreign particles, such as a virus) in order to be triggered to produce antibodies against that foreign material (in this scenario, the Rabies virus). If too little of a dose is presented to the immune system, no immune response will occur, so no or not enough antibodies will be produced. This leaves your pet without the help it needs to fight off invading Rabies viral particles if that pet is bitten by a rabid animal in the future. Thus, your veterinarian is doing nothing wrong by injecting your little Chihuahua with the same advised dose that a Saint Bernard is also given. In contrast, if a veterinarian under-doses your pet, this act is not only illegal but is also an ethical violation that leaves your pet inadequately protected against Rabies.
It is true, however, that some dogs and cats may have an adverse reaction to their Rabies vaccine, as they could to other vaccine types too. Hypersensitivity reactions can sometimes occur, ranging from local pain and swelling at the injection site, to the triggering of various autoimmune reactions, to anaphylaxis and death. In such cases, your veterinarian may recommend that your pet does not receive further Rabies vaccine boosters in the future. Bloodwork should be regularly performed (ideally annually) to track your pet’s Rabies titer, a measurement of your pet’s antibodies that, if at a high enough level, should protect that pet against Rabies infection in an exposure scenario. Be forewarned, however, that you should still take extra precautions to keep an unvaccinated dog or cat (regardless of his or her titer) away from wildlife Rabies vectors. Additionally, some travel stipulations in certain regions may deny a sufficient Rabies titer as proof of proper protection against Rabies, preventing travel entry for your pet.
Fortunately, most animals respond very well with no to minimal reaction to the Rabies vaccine. However, some cats may also be at risk for developing a malignant tumor known as a vaccine-associated sarcoma (fibrosarcoma) secondary to the Rabies vaccine injection. Other vaccines may also carry this risk in some felines, especially the feline leukemia virus (FeLV) vaccine. The current theory is that cats who develop fibrosarcomas at the site of a vaccine injection are genetically predisposed to over-exaggerated inflammatory reactions to any injection. Some of these cats may require limb amputation to fully excise the tumor and prevent metastasis (cancer spread to the lungs and other organs). However, this risk is very low and only occurs in a tiny percentage of vaccinated felines.
As with most decisions, the risk vs. benefit of vaccinating an individual animal must be carefully weighed. However, in the vast majority of cases, the benefit of vaccinating a pet that resides in or travels to an area with potential Rabies exposure astronomically outweighs the risk of potential vaccine reactions. The benefit of a Rabies vaccine can save the life of your dog or cat in the case of Rabies exposure, and properly vaccinating your pets can also reduces the risk of Rabies in people as well, saving human lives.
Moreover, a recent study by Dr. Darryn Knobel (Associate Professor of Epidemiology and Population Health, Ross University School of Veterinary Medicine, Saint Kitts and Nevis) suggests that the Rabies vaccine may reduce the overall mortality risk of puppies and kittens, not only due to preventing Rabies but perhaps also by improving your pet’s overall immune system, allowing your pet to ward off other potential infectious threats as well. Further investigation is necessary in understanding the full mechanism behind these preliminary results.
Fun Fact: Veterinarians in countries where Rabies is a concern are required to receive a human Rabies vaccine to prevent them from acquiring a potential Rabies infection from their patients.
Learn about the Rabies vaccine as well as other necessary vaccines for dogs and cats in The Meowing Vet’s other articles on pet vaccination and preventative medicine:
Dog & Puppy Vaccines
Cat & Kitten Vaccines
How else can I reduce the risk of Rabies?
View this video from the American Veterinary Medical Association (AVMA) to understand additional safety tips that you can easily implement to reduce your and your pet’s Rabies risk.
What happens if my dog or cat bites or is bitten by another animal? What if I am exposed to a rabid animal?
As discussed, all wildlife vectors in countries where Rabies is a concern should be assumed to carry Rabies until otherwise disproved. Therefore, if you wake up to find a bat flying around your room, are bitten by a wild mammal, or contact the saliva of a potential Rabies vector, immediately wash the affected area thoroughly. The Rabies virus is easily inactivated (meaning it won’t be viable to amount an infection) in soap and water or disinfectants. After cleaning your wound, contact both animal control and your local physician or health department to receive the post-exposure prophylaxis (PEP) protocol, involving wound care, a series of Rabies vaccine injections, and sometimes administration of Rabies immunoglobulin (RIG), an antibody to help fight infection. Prompt post-exposure prophylaxis SAVES LIVES!!! Do not delay reporting a dog, cat, or wild animal bite! Ask your veterinarian to help direct you if you don’t know who else to call.
As addressed, if you are bitten by a pet, whether it belongs to you or someone else, and especially if it breaks the skin, you should also contact your doctor about any necessary treatments he or she may recommend. Depending on the severity of the bite, your physician may be legally required to report a dog bite to their regional health department, who will require to see proof of vaccination of the pet that bit you.
If your pet bites or is bitten by another animal (wild mammal or another pet), certain protocols are legally mandated to prevent a potential Rabies outbreak. The following policies are currently in place in America:
- If a dog or cat bites a person, it must be quarantined for 10 days. (Why 10 days? Because the Rabies virus can be shed by an infected animal for up to 10 days before that any displays the onset of any clinical signs of the disease. If the animal does not fall ill during this 10 day period, then it is deemed not to be a rabid threat.)
- If the pet is vaccinated against Rabies, it can be quarantined at home.
- If animal is not vaccinated, the health department or local police may require quarantine at another location (such as a veterinary clinic). If this is not possible, the animal may be euthanized for autopsy (necropsy) to test for Rabies.
- If your dog or cat is exposed to a potentially rabid animal (wildlife vector or another pet), one of the following scenarios is mandated:
- If the pet is vaccinated against Rabies, its vaccine should be boostered immediately, and it must be observed for 45 days. If it does not display neurological signs suggestive of Rabies, the pet is then released by the public health department veterinarian.
- If the dog or cat is not vaccinated against Rabies, or if its vaccine status is out of date (i.e. was not properly boostered), a strict quarantine is required for 6 months. If the animal displays no signs of Rabies within this time frame, the pet is released to its owner. If the quarantine is not possible or if the pet owner does not concede, the animal may be ordered to be euthanized and tested via a post-mortem exam (necropsy, as previously discussed). The latter scenario is most likely to happen if a child was exposed to the pet in question or to the same rabid animal that the pet was also exposed.
To avoid the risk that your pet is required to be put down after a Rabies scare, be sure that he or she is up-to-date on the Rabies vaccine if you live in a high-risk region of the world. I cannot stress enough the importance of prevention when it comes to Rabies.
If you and your pet reside in or travel to a country that harbors the Rabies virus, The Meowing Vet urges you to discuss proper precautions with your local veterinarian. If your pet is at risk of being exposed to Rabies, discuss vaccination with your vet today. Please share this article with all your friends and family to educate them about the risk of Rabies in particular countries; you may help save a life.
– Maranda Elswick, DVM
