What is rabies, and why is vaccination important?

Rabies is a viral disease caused by the rabies virus. This disease is a serious problem in many parts of the world, including the USA. Humans and wildlife are infected by the bite of rabid animals and most often this disease leads to death. This article is intended to be an overview of this disease, with the hope of encouraging rabies vaccination.

We have rabies in Oregon. According to the state veterinarian, there were 14 cases in 2012 and already 2+ cases in 2013. These cases were mostly in bats and foxes and they were irregularly spread around the state. Clatsop County did not have any reported cases, but it is not clear if any specimens were sent in for testing. At Astoria Animal Hospital, we did field calls regarding human/animal and bat contact but none of bats in question were sent to in for examination. As a cautionary note it is recommended never to handle a sick or injured bat, as roughly 10 percent of those tested test positive for rabies virus. If handling a bat is required, use gloves, an instrument/tool (shovel), and place it in a plastic container (with small air-holes). Do not put yourself at risk of bite, and teach your children this important lesson.

A virus is a small infectious agent that can replicate only inside the living cells of an organism. There are many types of viruses and they are broken down in the same way other species are broken down, using the systematic style of scientific nomenclature. Rabies virus is in the family Rhabdoviridiae, the genus Lyssavirus, and the species rabies. Rabies comes from the Latin word meaning “madness,” which gives a clue to the clinical signs of central nervous system (CNS) disease.

Madness, traditionally, means insanity, frenzy, rage, and intense excitement without reason or cause. With rabies disease, early-stage symptoms are malaise, headache and fever, progressing to acute pain, violent movements, uncontrolled excitement, depression, and hydrophobia. Finally, the patient may experience periods of mania and lethargy, eventually leading to coma. The primary cause of death is usually respiratory insufficiency.

The diagnosis of this disease is based solely on history of being bitten by a rabid (or suspected rabid) animal and clinical signs.  There are no tests that can be completed to give insight to this once clinical signs have started. The only test available to confirm or disprove diagnosis is a post-death examination of the refrigerated brain. This is why the state veterinarian can order euthanasia if the disease is suspected (see below).

When bitten by a rabid animal, the virus enters the wound. From this point it travels toward the brain using the nerves as a pathway. The distance from the point of entry (bite wound) from the brain can affect how long clinical signs take to appear. For example, if bitten on the ear clinical signs of rabies infection may appear faster than if bitten on the foot of the back leg. This is simply because the virus has to travel farther to get to the brain. Once the rabies infection reaches the brain, the virus then spreads out to the other organs of the body, with the salivary glands getting the bulk of infection. This is why the bite of rabid animals spreads the disease.

Rabies vaccination is one of the strongest tools (in fact, the only tool) we have to prevent this disease. A worldwide vaccination campaign has made this disease relatively infrequent, which is a good thing. The state veterinarian recommends dogs and cats are to be vaccinated by three months of age by a licensed veterinarian. The animal licensing requirements are set by the jurisdiction in which you live. Clatsop County requires dogs to be licensed; licensing your dogs is a very good thing and can be completed through the local animal shelter.

An owner of pets (including cats, dogs, ferrets, and ruminants) should consider having their pet/livestock vaccinated. The animal should NEVER be out of compliance with the vaccine, NEVER. Should an animal that is rabid bite your animal the state veterinarian could order euthanasia immediately. If you can demonstrate that your animal is vaccinated and this happens at consistent and legal intervals (1 or 3 years) the state veterinarian may order revaccination and quarantine (not euthanasia). The fact that Clatsop County doesn’t require cats to be licensed, does not mean they don’t need rabies vaccines–they do need them.   Bats are the most common carriers of this disease in the state of Oregon. Bats do fly into our homes, therefore even indoor-only cats should have this vaccine (if only to protect their canine counterparts) as a matter of urgency.

The rabies vaccine, according to the veterinary practice act, requires administration by a licensed veterinarian. There is a good rationale behind this—a veterinarian must sign (preferably with an original signature) their certificate, which in effect guarantees that the vaccine was in fact given to this animal by the signing vet. The rabies certificate should have all the information about the vaccine that was given: lot number, expiration date, location given on the animal, duration of effect, etc. The exam that should precede the rabies vaccine should demonstrate that the animal was in good health and not already sick; therefore the rabies vaccine should have its best effect in protecting the animal from this terrible disease.

Rabies is a preventable disease. Rabies is a terrible disease with terrible consequences. Vaccination of animals is a very good tool to prevent unwanted consequences. Make an appointment with your veterinarian to discuss this more and get your animal vaccinated.

Dr. Dannell Davis
Astoria Animal Hospital