Glossary of Animal Health Terms
PART 1 Terms
in general use
PART 2 The
four diseases in the health schemes
Prepared for the British Limousin Cattle Society
September 2004
PART 1
ACCREDITED
A high state of freedom from a particular disease regularly monitored by testing
for that disease.
ANTIBODIES
Immune substances produced as a result of infection or vaccination
or acquired as in colostrum or antisera.
ANTIGENS
Microorganisms that cause disease.
ANTISERA
Serum containing antibodies to a particular disease or diseases which
when administered to an animal provides it with temporary immunity.
BIOSECURITY
The principle of taking measures to keep premises and therefore stock
free from incoming diseases.
BVD
Bovine Viral Diarrhoea (see Part 2).
CARRIER
An animal having disease causing organisms within it and capable of
infecting others. It may show no symptoms of the disease itself.
CHeCS
An independent self regulating body which sets standards for the control
and eradication of four non statutory diseases (see Part 2) to which
licensed participating health schemes must conform to.
COLOSTRUM
The first milk rich in antibodies – the calf’s first source
of immunity. Colostrum may also contain infections for example Johnes
disease.
CONCURRENT INFECTIONS
When an animal may be infected with two or more infections at the same
time.
D.N.A.
The genetic blueprint of all life. In the future testing for infectious
organisms may involve looking for their D.N.A. in the diagnosis of
the disease.
D.V.M.
Divisional Veterinary Manager to whose office all incidents of notifiable
diseases should be reported.
ENCEPHALOPATHIES
Degenerative nervous system diseases which affect all species and may
be transmissible.
ERADICATION
The process of removing a particular infection from a herd.
HERDCARE
A health scheme licensed by CHeCS and administered by BIOBEST.
H.I. HEALTH
Highlands and Islands Health Scheme licensed by CHeCS and administered
OLA (Orkney Livestock Association) and Biobest Laboratories
IBR
Infectious Bovine Rhinotraceitis (see Part 2).
IMMUNITY
An animal has immunity to a disease when it is protected by antibodies
to that disease. It may have made these antibodies itself as a result
of infection or vaccination or acquired them passively in colostrums
or antiserum.
IMMUNOSUPPRESSION
The animal’s ability to make antibodies may be interfered with
by drugs or concurrent infections, for example BVD virus.
INCUBATION PERIOD
The time from when an animal is first infected with a disease until
symptoms develop. For most diseases this is a few days but for encephalopies
and Johnes disease for example the incubation period can be years.
MAP
Mycobacterium avium subspecies psuedotuberculosis – the scientific
name for Johnes disease causative organism.
MONITORED FREE
A herd is said to be monitored free of a disease when regular tests
come back negative but there is still an element of doubt. The disease
in question may have a long incubation period and there are limitations
in the ability of the current test procedures to pick up these animals.
MUCOSAL DISEASE
A fatal enteritis of young stock due to BVD complex.
NAÏVE
An animal is said to be naïve when it has no immunity to a particular
disease. New born calves before receiving colostrum are naïve.
Animals participating in a health scheme in which that disease has
been eradicated are naïve to it and if introduced to a new herd
where that disease exists are naïve and therefore susceptible
to it.
NOTIFIABLE
A disease is notifiable if there is a statutory requirement to notify
the D.V.M of any suspicion of that disease. Examples are FMD and brucellosis.
PCHS
Premium Cattle Health Scheme administered by SAC.
PI
Persistently Infected. Calves infected with BVD virus during the first
third of pregnancy and survive to term remain persistently infected.
They release virus throughout their lives and are the main way in
which the virus is spread. They may appear normal.
QUARANTINE
A period of isolation before an animal joins its intended herd. Animals
incubating disease should show symptoms during this period as long
as the incubation period does not exceed the quarantine period.
SAC
Scottish Agricultural College.
SCREENING
Testing a representative sample of the herd for one or more diseases.
TRANSIENT INFECTION
An animal meets an infection, makes antibodies to it and recovers with
no permanent side effects. For example a bull goes to market, meets
BVD, has a temperature for a day, recovers and goes to its new owner
symptomless. However the transient infection may have left him temporarily
infertile.
VACCINES
Substances which when administered to an animal cause its immune system
to respond by actively making antibodies to that disease. Vaccines
may be dead or live.
Marker Vaccines
The vaccine is labelled in such a way that the antibodies taken from
an animal vaccinated with a marker vaccine can be differentiated from
antibodies that it may have made from having been infected with that
disease.
Booster Vaccines
The same vaccine that was used in the initial course may need to be
repeated at recommended intervals. Exposure to the disease concerned
may naturally boost the animal’s immunity if previously vaccinated.
ZOONOSIS
A disease of animals that can infect human beings, for example leptospirosis.
PART 2
The four diseases currently available for control in cattle health
schemes are:-
IBR - Infectious Bovine
Rhinotracheitis
BVD - Bovine Virus Diarrhoea
Leptospirosis
Johnes Disease
IBR
IBR is an acute viral disease. In young animals it mainly affects
the upper respiratory tract and can lead to a fatal pneumonia. In mature
animals it causes abortions and reduced fertility. Once infected an
animal remains infected for life and may release infected virus throughout
its life when stressed. It is spread via airborne secretions and bulls’ semen.
For pedigree breeders IBR is important in that animals and herds that
have had contact with IBR are barred from export to certain countries.
When the technology of marker vaccines is better understood they will
have their part to play. Some European countries are free of IBR It
may be controlled with vaccine but take veterinary advice especially
where animals, embryos and semen from the herd may be suitable for
export.
BVD
BVD is a complex of diseases of viral origin. Effects of the disease
may be reduced fertility, abortion, foetal abnormalities, enteritis
and mucosal disease. It is spread by PIs (Persistently Infected calves)
and semen from transiently infected bulls, contaminated needles and
equipment. Control is by biosecurity, removing persistently infected
calves and vaccination.
LEPTOSPIROSIS
Leptospirosis disease in cattle is caused by two species of Leptospiria
characterised in dairy cattle by milk drop and in beef cattle by abortions
in the second half of pregnancy. Infection is via infected urine either
from the cow or urine contaminated water or pasture. It can affect
human beings. Infected animals may be carriers for life. Control in
an infected herd is by vaccination
JOHNES
Johnes Disease (paratuberculosi) also known as MAP is a chronic infectious
bacterial enteritis that results in persistent diarrhoea, progressive
wasting and eventual death. It is untreatable. It has an incubation
period of 2-6 years. Animals are usually infected when young. The calf
may be infected while in the womb, drinking infected colostrums and
milk, or consuming food and water contaminated by Johnes infected faeces.
The organism may last for a year in slurry or on pastures. In the individual
animal diagnosis by laboratory means is unreliable until the disease
symptoms are well established and hence a whole herd testing procedure
is adopted.
The term Monitored Free has been adopted in describing freedom from Johnes
disease status of a herd. In herds where no case of Johnes disease has
been diagnosed, two clear blood tests 12 months apart of all animals
two years and over are required for Monitored Free status. In herds that
have had a positive case, three clear tests of all cattle over two years
old at yearly intervals are required for Monitored Free status. However,
due to the long incubation of the disease there may still be an unexpected
positive. A vaccine is available but the implications of using it in
a herd wishing to sell breeding stock need to be very carefully considered
by the breeder.
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