With a close to 100 percent mortality rate once symptoms appear, rabies is one of the most devastating viruses on the planet. It can infect any mammal, including humans. Thanks to stringent vaccination requirements, dogs now only constitute 1 percent of reported rabid animals in the United States each year. However, without regular vaccinations, your dog is at risk of contracting this deadly virus, which attacks the nervous system and causes symptoms that include extreme changes in behavior, paralysis, seizures, respiratory failure, and death.
Should your dog come in contact with a rabid animal, you may be required to euthanize it if it has never been vaccinated. Because there is no effective treatment for rabies, public health departments take strong action to prevent the spread of this disease. Here's what you need to know about the cause, symptoms, and most importantly, prevention of rabies in dogs.
What Is Rabies?
Rabies is a neurological disease caused by a virus in the Lyssavirus genus. Any mammal of any age can potentially be infected with the rabies virus. It is spread through bites or scratches that contain the saliva of the infected animal.
In much of the world, dogs are the animal most likely to catch rabies and spread it to humans. Around 59,000 people die annually from this disease, mostly in Africa and Asia. However, in North America, due to widespread vaccination requirements, raccoons, skunks, bats, and foxes are now the animals most likely to carry and spread this serious disease, which kills one or two people each year in the US.
Symptoms of Rabies in Dogs
A dog with rabies generally goes through two or three stages of symptoms. The first stage, which lasts two or three days, is the prodromal stage. During this time, the dog tends to exhibit changes in personality. Your normally friendly dog might turn shy or anxious, or your normally quiet dog might become very restless and active.
Next, the dog enters one of two forms of disease symptoms: furious rabies or dumb rabies. Some dogs will go through both of these forms, others will only experience the dumb form.
With furious rabies, the dog may become very aggressive and excited. It might chew or eat odd objects, such as dirt or stones. Finally, the dog will develop paralysis, followed by seizures and death.
With dumb rabies, which is the most common form in dogs, the animal experiences progressive paralysis, difficulty swallowing, facial distortions, coma, and eventually death.
While every animal is slightly different, the following are common symptoms in dogs with rabies.
Initial signs of a dog infected with rabies include behavior and personality changes. Timid dogs might become aggressive, while quiet dogs become restless and friendly dogs turn shy.
Licking the Bite Wound
A dog will excessively lick the site of the original bite wound. This can give you a good visual indication there is a serious problem that your vet needs to address.
Sensitivities to Environment
A rabid dog often will become restless and agitated, and it will overreact to sights and sounds in the environment.
Aggression and Disorientation
As rabies progresses, a dog may become extremely aggressive, and then disoriented. This aggression can also cause the dog to self-mutilate or attempt to bite people or other animals.
A dog with rabies will begin to have seizures as the disease progresses.
Dogs with rabies may also experience paralysis of the head and neck area.
Paralysis causes difficulty swallowing. This inability to swallow produces excessive drooling and salivation, which is where the term "foaming at the mouth" comes from as it relates to rabies.
An infected dog in the last stages of rabies will have difficulty breathing. Sadly, death soon follows.
Causes of Rabies
The rabies virus is transmitted through the saliva of an infected mammal. Should the infected animal bite an unvaccinated dog, or should the fresh saliva of the infected animal come into contact with an open scratch or sore on an unvaccinated dog's skin, the virus enters the dog's body and then penetrates the peripheral nerves. From there, the virus enters the spinal cord, where it reproduces rapidly. It then spreads into the dog's brain and finally into the salivary glands.
The incubation period for rabies can vary quite a bit, depending on the amount of virus in the saliva, the severity of the bite, and the distance from the bite to the spinal cord and brain. However, as a general rule, the incubation period in dogs ranges from two to eight weeks. Once symptoms begin, the prodromal phase generally lasts two or three days. The dog might then enter the furious form of the disease, which lasts anywhere from one to seven days, or might skip to the dumb form of rabies, which can last from two to four days. Most rabid dogs will die within eight days from the start of the symptoms.
Diagnosing Rabies in Dogs
The only way to definitively diagnose rabies in dogs is through a direct fluorescent antibody test (dFA) using samples of brain tissue that can only be obtained after death. Diagnosis in living animals is presumptive and based upon clinical signs and patient history. In pets that have been exposed to rabies, a quarantine period may be necessary to watch for signs of the disease. The quarantine period is typically 45 days in a dog that is current on its rabies vaccine.
Unfortunately, there is no cure or effective treatment for rabies. Should your dog be bitten or exposed to the saliva of an animal that has rabies, your veterinarian will advise you on your state's guidelines. Most states follow the guidelines of the Centers for Disease Control (CDC), which are:
- A dog that is current on its rabies vaccine should be immediately given a booster shot and then kept in quarantine for a 45-day observation period. If it develops any signs of any illness, it must be evaluated by a veterinarian. If the signs indicate rabies, the animal should be euthanized and its brain sent to a veterinary diagnostic laboratory for testing.
- A dog that has been vaccinated against rabies in the past, but is not current on its vaccination, will follow the same guidelines as outlined above.
- If the dog has never been vaccinated against rabies, the guidelines recommend it be immediately euthanized. If the owner refuses to do so, the alternative is to immediately vaccinate the dog and then place it in a very strict 4-month quarantine period. Should the dog develop signs of rabies during this period, it should be euthanized and its brain sent for testing.
Prognosis for Dogs With Rabies
Once the symptoms of rabies have appeared in animals (and humans), the prognosis is grim. Death usually occurs in a week or so after the onset of signs of the disease.
How to Prevent Rabies
Prevention is key when it comes to rabies, and fortunately, it is also quite simple. First and foremost, dogs and other pets should receive routine rabies vaccines. The first dose is usually given once the dog is at least three months of age, with a booster following one year later. After that, most dogs will require a booster every three years, although some rabies vaccines still require annual boosters. Talk to your vet about your options, and find out what the law in your area mandates.
Next to vaccination, minimizing exposure is the best way to prevent rabies. Do not allow your dog to roam out of your sight, especially in wooded areas where wild animal encounters are more common. Keep your dog on a leash, avoid interactions with unknown animals, and stay away from bats, which are frequent carriers of the virus.
If your pet is bitten by another animal, obtain as much information as possible about the offender. If the biting animal was someone's pet, get their contact information and find out about the vaccine history and possible past exposure to rabies. If it was a wild animal, you may not be able to find out much unless that wild animal is dead and can be tested. Either way, a visit to your veterinarian is in order.
Is Rabies Contagious to Humans?
Rabies is a zoonotic disease (a disease that can be spread from animals to people). That means humans are equally susceptible to the rabies virus if bitten by an infected animal. Bites to humans should be addressed immediately by a physician. The incubation period in humans before symptoms appear is on average two or three months, but can be as short as one week or as long as one year.
In humans, multiple extensive diagnostic tests can be run with samples of saliva, blood, hair, and skin, but these are not absolute, Humans exposed to rabies will need to undergo a regimen called postexposure prophylaxis (PEP), a series of injections that include immune globulin and rabies vaccine. PEP is not effective in humans after symptoms are noted. As with animals, rabies in humans is almost always fatal once the signs appear. Supportive care is the only option at this point. A human rarely dies in the United States from rabies, with only a handful of cases a year typically reported, mostly from bites from infected wildlife.
Rabies vaccines are also available for humans, though the protocol is more complicated. Therefore the vaccine is typically only given to people who work with pets or wildlife or those who travel to areas with high exposure risk. People who have received the vaccine will still need PEP after exposure to rabies.
Preventing rabies in humans is critical. Learn about dog bite prevention and teach your children how to be cautious around animals.
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Animals and Rabies. Centers for Disease Control.
Caring for Animals with Potential Exposure. Centers for Disease Control.
Rabies Around the World. Centers for Disease Control.
Rabies in the U.S. Centers for Disease Control.
Rabies in Dogs. VCA Animal Hospitals.
Rabies Vaccination in Dogs. Today’s Veterinary Practice.
Rabies Postexposure Prophylaxis (PEP). Centers for Disease Control.