Rabies is an acute viral inflammatory disease of the brain and nerves that can affect any mammal. In our area of the country, the most common carriers are bats, skunks, foxes, and coons. In other parts of the world, unvaccinated dog and cat bites are still the most common cause of human rabies.
It's counter to what most people think, but reported cases of people getting rabies from the bites of domestic cats have outnumbered those in dogs in the USA every year since 1987.
But just to be clear; ALL mammals can get and transmit rabies and with the exception of Hawaii and Britain, the disease is still a threat WORLD WIDE.
Transmission and Pathogenesis:
Transmission of the disease to humans is almost always by the bite of a rabid animal. The rabid animal will have infective concentrations of the virus in it's blood and other body fluids including saliva. And because the disease causes inflammation of the brain, it makes animals "mad", crazy, and erratic in it's behavior making it much more likely to bite any nearby creature thereby transmitting saliva into a wound.
From a human viewpoint, the most common way for rabies to be transmitted is for saliva from a rabid animal getting into a fresh wound.
But the rabies virus is also in the tissue, blood, and other body fluids of a rabid animal and can be transmitted through ingestion.
That means that if a predator... including human hunters, or animals that eat carrion ... eats an animal carrying the rabies virus, they are at risk of getting the disease themselves. This might be the most common way for the disease to spread amoung animals and would explain why the disease is most common in carnivores.
Animals that are drooling excessively and acting aggressive, or exhibiting other symptoms of rabies are certainly a threat and can transmit the disease.
But there's probably enough virus built up in that animal's blood and saliva to transmit the disease for 3-8 days BEFORE there are any symptoms. That's why we often quarantine a normal acting animal for 10 days should it bite a human to observe it's behavior. If it has rabies, it should start showing symptoms by 10 days. Unfortunately we don't have a reliable test for rabies that doesn't involve getting a brain sample which means cutting of the head.
Rabies virus has not been isolated from skunk spray.
Clearing up some details:
Let's say a human is bitten by an unvaccinated dog or cat...
If that unvaccinated dog or cat has rabies virus in it's saliva, that virus will be transmitted into the bite wound. But the virus is NOT likely to immediately spread to the rest of your body. It usually remains in the area of the bite for several weeks.
This is called the incubation period. This period is quite variable from one species to another but in the human it's thought to last at least 10 days.
This is why we can wait up to 10 days before starting post exposure treatment, giving us time to observe the dog or cat for symptoms. It is also why you can greatly protect yourself or your child from getting rabies ... even if bit by a rabid animal ... simply by washing out the wound well. Rabies virus is not a super bug; it's destroyed by contact with most antiseptics.
After replication within muscle cells near the site of inoculation ... a process that usually takes at least 10 days in the human ... the virus travels through nerves to the spinal cord and eventually to the brain.
After reaching the brain, the virus continues to multiply and spreads to the peripheral nerves and salivary glands. Therefore, if an animal is capable of transmitting rabies through its saliva, virus will be detectable in the brain.
Clinical signs of rabies are rarely definitive. Meaning that just because an animal is acting drunk, frightened, or is drooling alot doesn't prove it has rabies. It simply means BEWARE ... especially if it's a feral animal.
Rabid animals of all species exhibit typical signs of brain inflammation.
The most reliable signs, regardless of species, are:
Unexplained paralysis or twitching of the muscles
Acting nervous, irritable, or frightened
Acting "drunk" or ataxic
Uncharacteristic aggressiveness or viciousness
Wild animals that don't seem to have a natural fear of man is a BIG warning sign. As is seeing nocturnal animals like skunks and coons hanging out in the daytime.
Remember though, that rabies can be transmitted from rabid animals for several days before clinical symptoms are obvious.
Once symptoms are obvious, paralysis followed by death progresses rapidly with death within about 10 days almost certain.
This is the classical "mad-dog syndrome," although it occurs in all species.
There is rarely any evidence of paralysis during this stage.
The animal becomes irrational and, with the slightest provocation, may viciously and aggressively use its teeth, claws, horns, or hooves.
The posture and expression is one of alertness and anxiety, with pupils dilated.
Noise invites attack.
Such animals lose all caution and fear of natural enemies.
Carnivores with this form of rabies frequently roam extensively, attacking other animals, including people, and any moving object.
They commonly swallow foreign objects, e.g., feces, straw, sticks, and stones.
Rabid dogs chew the wire and frame of their cages, breaking their teeth, and will follow a hand moved in front of the cage, attempting to bite.
Young pups apparently seek human companionship and are overly playful, but bite even when petted, usually becoming vicious in a few hours.
Rabid skunks appear to seek out and attack litters of puppies or kittens.
Rabid domestic cats and bobcats attack suddenly, biting and scratching viciously. As the disease progresses, muscular incoordination and seizures are common. Death is the result of progressive paralysis.
This is first manifest by paralysis of the throat and jaw muscles, often with profuse salivation and inability to swallow.
Dropping of the lower jaw is common in dogs.
Owners frequently examine the mouth of dogs and livestock searching for a foreign body or administer medication with their bare hands, thereby exposing themselves to rabies.
These animals are not vicious and rarely attempt to bite. The paralysis progresses rapidly to all parts of the body, and coma and death follow in a few hours.
Comprehensive guidelines for control in dogs have been prepared by the World Health Organization and include the following:
1. notification of suspected cases, and destruction of dogs with clinical signs and dogs bitten by a suspected rabid animal
2. reduction of contact rates between susceptible dogs by leash laws, dog movement control, and quarantine
3. mass immunization of dogs by campaigns and by continuing vaccination of young dogs
4. stray dog control and destruction of unvaccinated dogs with low levels of dependency on, or restriction by, man
5. dog registration.
Note: Most countries now have similar protocols for cats
Also recommended: If an exposed animal is currently vaccinated, it should be revaccinated immediately and closely observed for 45 days
What to do if you or your child is bitten by an animal
(at least as far as rabies is concerned)
MOST IMPORTANT: wash out the wound ASAP. If the animal happens to be rabid, the rabies virus stays in the area of the bite wound for awhile and is usually destroyed by vigorous cleaning and by most antiseptics.
You're supposed to report any animal bite to your county environmental health office. I'm not so sure how practical that is but I certainly recommend this action if you are bit by an animal that hasn't been vaccinated for rabies. Or if you're not sure it has been vaccinated for rabies. This would certainly include all mammalian wildlife and bats.
If you can contain the animal safely, do it. That way, animal control officers can find out if it has or hasn't been vaccinated and then make a decision on whether or not to quarantine the animal or euthanize it and send if off for testing.
You, your physician, & state health officials will decide if and when post exposure treatment is appropriate.
Your veterinarian is not the person that makes this decision.
Your veterinarian's role is to:
- Keep records of all pets vaccinated
- To euthanize and remove the head for testing should that be done
- May or may not be responsible for providing quarantine and observation facilities
- To inform the public about rabies (like I'm doing now)
- To encourage ALL PET OWNERS TO VACCINATE THEIR PETS soon after 12 weeks of age and then every 1-3 years as required by law. Your vet is also responsible for making reasonably sure that pets are reasonable healthy when they get their vaccine. (Vaccines are not effective unless the pet has a healthy immune system)
Pet Owner Responsibility if your Pet Bites Someone:
The pet owner is usually responsible for veterinary fees if the county requires that your pet be quarantined at a veterinary or county facility.
The county or state will often fine the pet owner, often with BIG FINES, if your animal is not current on vaccination and/or is in non compliance with local leash laws etc
Pet owners may also fine themselves liable to civil law suits and/or responsible for medical bills for the human that was bitten by their dog or cat. This can even be true if the person is an uninvited guess on your property. An example would be a child petting your cranky old cat in the driveway. If it's not vaccinated, you could be in big trouble. And certainly, if you have a pet known to be aggressive or have a dog breed precieved to be dangerous you will be extra liable unless your pet is not only vaccinated but under reasonable control and confinement.
Rabies vaccine schedule recommended for most pets
(See comments in the column to your left)
@ 6 weeks old: a good exam, kitten or puppy vaccines, parasite control
@ 10 weeks old: kitten or puppy booster vaccines, start heartworm prevention if in a heartworm prevelent area of the country. 1st Leukemia vaccine recommended in most kittens. A second leukemia vaccine booster is recommended about a month later and then yearly OR NOT afterwards depending on multiple factors such as your cat's age and exposure level.
@ 14 weeks old: The immune system of the puppy or kitten is now mature enough for "adult" vaccine boosters and 1st Rabies Vaccine. Most states REQUIRE rabies vaccine before the pet is 6 months or 24 weeks old. Also please consider spaying or castration of your pet before 6 months of age
1 year later (@ 16 months old): Annual wellness exam, vaccination boosters as recommended by your vet, and Repeat 1 year Rabies vaccination.
1 year later: repeat wellness exam, vaccine boosters as recommended by your vet and either a 1, 2, or 3 year rabies vaccination depending on the laws of your state.
Yearly thereafter: a good wellness exam. Remember that pets age about 7 years for every one of "our years", so waiting a year between routine physicals is actually a long time and we vets frequently detect problems unnoticed by the owner on pets that were prefectly healthy the previous year. Vaccine boosters as recommended by your vet, and rabies vaccine boosters when if due.
For more detailed discussion of the latest general vaccination recommendations , please go to our page about the topic for either dogs or cats.
The Compendium of Animal Rabies Control, which is updated annually by the National Association of State Public Health Veterinarians (NASPHV), summarizes the most current recommendations for the USA and lists all USDA-licensed rabies vaccines.
Recommended vaccination frequency varies among states from every 1 to3 years.
Most states now require rabies vaccination of cats as well as dogs.
Rabies vaccines are also available and required or recommended for use in ferrets, horses, cattle, and sheep.
No vaccine is approved for use in wildlife kept as pets.
Most vets recommend that if you do keep pet skunks, coons, or other high risk wildlife as pets, that these be vaccinated with a killed rabies vaccine on the grounds that it won't hurt and may very well prevent the spread of rabies BUT none of our available vaccines have been tested on wildlife to make sure they work. So no rabies certificate is given ... just a note in your records that the vaccine was given ... along with the warning that this vaccine is NOT approved as safe and effective.
and protective immunity from the commercially available vaccines has not been demonstrated in these species.
Management of Suspected Rabies Cases-Exposure of Pets:
Where terrestrial wildlife or bat rabies is known to occur, any animal bitten or scratched by a wild, carnivorous mammal (or a bat) not available for testing should be regarded as having been exposed to rabies.
The NASPHV recommends that any unvaccinated dog or cat exposed to rabies be destroyed immediately.
Unvaccinated animals that have bitten a human are usually euthanized and their head removed and sent into the state lab to be tested for rabies ... so that if the result is positive, the human bit by the animal can be started on post exposure treatment.
Rules and regulations vary a little from state to state, but an alternative to immediate euthanasia, is that the animal be put under quarantine for at least 10 days to observe for symptoms. If the animal had rabies disease advanced enough to have infective levels of virus in it's saliva, then it will usually have obvious behavioral changes or paralysis within 8 days (10 or more days in quarantine is just to be sure).
It's almost always okay to delay post exposure rabies treatment for 10 days, so the 10 day observation method usually works out.
But some authorities require strict isolation for 6 mo and vaccinated against rabies 1 mo before release.
Other rabies authorities recommend vaccination at the beginning of the isolation period.
Clearing up the confusion about
1, 2, or 3 year rabies vaccinations:
First of all, let's not forget that because of strigent laws requiring all pets be vaccinated, the disease has gone from being a common cause of human death in Western countries to rare.
Each state has a different law concerning how often you need to vaccinate your pet for rabies. The longest accepted period in the U.S. to date is 3 years.
You should obey the law in your state.
Medically, we suspect that most pets, after an initial rabies vaccine ...especially if given a booster vaccine the following year... will have adequate immunity from the disease for at least 3 years. Probably longer but 3 years is the longest period for which there are reliable studies.
BUT notice I said "most pets".
Duration of immunity is so variable from pet to pet depending on their genetics, general health, immune suppression medications, parasite load, and level of nutrition.
Our best recommendation:
Vaccinate animals that have never been vaccinated before, or young (under 3 years) cats and dogs yearly ... even if your state legally only requires the vaccine every 2 or 3 years. Why? Because getting a booster vaccine greatly improves immunity to the disease.
Once the pet has had 2 vaccines, about 1 year apart, then switch over to the every 2nd or 3rd year protocol... whichever is approved in your state.
One More Comment:
I told you that the incubation period for humans is usually at least 10 days, meaning that the virus hangs around the bite wound site for at least that long before replicating in high enough quanity to start it's journey up the nervous system to the brain. Once the virus reaches the brain, whether it be in a dog, human, or any other animal, neural symptoms and death usually follow quickly.
But the incubation period is much longer in some non -human species. It may last months in raccoons and skunks. That's one of the reasons these wild animals are not recommended as pets. Just because they act friendly and normal for weeks after you acquire them doesn't mean they aren't harboring rabies virus.