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Rabies
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The rabies virus
is a species of the genus Lyssavirus, of the family Rhabdoviridae, or
bullet-shaped RNA viruses. Rabies is a fatal infection
transmitted through the saliva of many animals. Although rabies
occurs primarily in warm-blooded animals (both domestic and wild), it
can be transmitted to man, usually by a bite from an infected animal or
through saliva entering a wound already present in the skin.
Foxes are the most important carriers of infection in Europe, followed
by dogs, cats and small rodents. The virus travels via the nerves to
the brain, where it sets up inflammation (encephalitis) causing causing
progressive paralysis and coma. It then returns via the nerves to
enter the salivary glands and other organs.
The time between
infection and positive signs of the disease being shown may be several
months but since most animals bite other animals around the head and
mouth, the virus usually reaches the brain more quickly. The incubation
period being 2-8 weeks. Once symptoms present, rabies is a fatal
infection and dogs seldom survive for more than 15 days. Positive
proof of the disease is ascertained by post-mortem laboratory tests on
the dogs brain.
There are three phases to the disease
The Prodromal Phase
Following infection, the virus enters an eclipse during which its
effects on the body are negligible. At the site of the bite the
rabies virus enters directly into the peripheral nerves or replicates
in tissue at the bite site, entering the nerves later.
In dogs, this phase of the disease typically lasts for two or three
days. During the next period the animal becomes nervous and
anxious. It may withdraw from contact and run a fever.
Personality changes become common. Friendly dogs may become
fearful or aggressive and normally fearful or aggressive dogs may
become friendly. The site of their bite evidently itches or stings
them, because they frequently lick and worry the area.
The Furious Phase
Once the virus has entered the peripheral nerves it is transported via
sensory and motor nerve fibers to the brain. The virus also spread from
the brain to other highly innervated (supplied) sites including the
salivary glands. This is the time the virus is present in the animals
saliva.
After passing through the prodromal phase dogs and cats pass through a
stage characterized by irritability to stimuli of sight and sound.
This stage can last one to seven days. These animals become restless,
aggressive and viscous. Dogs in this phase can chew the metal
bars of their cage until they injured themselves severely. Dogs
and cats in this stage of the disease may roam and wander great
distances in an aimless fashion. Eventually these animals become
ataxic (wobbly) and may develop seizures and die.
The Dumb Phase
This is sometimes called the paralytic phase. Some animals develop this
stage after a prodromal or furious period. This is the stage in which
the nerves of the head and throat become paralyzed. Animals in
this state drool and walk about with their mouth agape. They are unable
to swallow. Owners often think their pets in this condition have some
object lodged in their throat. During a period of about a week these
animals become more and more paralyzed and finally die. Many more
dogs pass directly into this stage from the prodromal stage, never
developing the furious stage of rabies. Cows in this phase often bellow
and extend their necks as if their throat was obstructed. It is
common for farmers to attempt to remove a suspected apple or corncob
from these animals’ throat and in so doing they become exposed to
rabies.
The last
case of indigenous terrestrial animal rabies in Great Britain was in
1922, and the last recorded case of rabies outside quarantine
occurred in 1969 and 1970 when two imported dogs died soon after
completing 6 months quarantine. Since then, most cases of rabies
in the UK have only occurred in quarantined animals or in people
infected abroad. The exception is a case of human rabies in a bat
handler infected with European Bat Lyssavirus 2 (EBL2) in Scotland in
2002. Before that incident, a bat infected with EBL2 was
discovered in Lancashire earlier in 2002. Another bat of unknown
country of origin infected with EBL2 was found in Newhaven, Sussex in
1996. At that time it was thought to have come from another
country, for example flown across the channel from France, but in 2003,
it was recognised that UK bats may now carry EBL2. Rabies is very
poorly reported and under-notified in the UK. Since 1902, there have
been at least 24 deaths from imported classical rabies reported in the
UK. All but two of these resulted from a dog bite (one was from a
cat and the other exposure was unknown) and 63% of deaths were after an
exposure in the Indian Sub-Continent. The most recent imported
cases occurred in 2001. One in an overseas visitor from Nigeria,
who had sustained a dog bite on the lower leg five months previously,
and the other, a UK resident of Filipino origin who had also been
bitten by a dog whilst in the Philippines. None of these cases
that have occurred in the UK were known to have received pre-or
post-exposure prophylaxis.
Source:
http://www.nathnac.org/travel/factsheets/rabies1.htm
Doglopaedia A complete guide to dog care J.M. Evans and Kay White
http://www.2ndchance.info/rabies.htm
The above information is simply informational. It's intent is
not to replace the advice of a veterinarian nor to assist you in making
a diagnosis of your pet. Please consult with your own veterinarian for
confirmation of any diagnosis. Your pets life may depend on it