Download AG-ASB-02.421-18.1P Animal_Diseases

Animal Diseases
Modified by Georgia Agricultural
Education Office
June, 2002
August 2008
Disease
• Broad definition – not being
at ease or uncomfortable
• Producers have a vested
interest to keep their
animals healthy
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Healthy Animals
• Grow faster and produce
more profit for their owners
• Some diseases are mild,
others may be severe and
cause rapid death
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Sick animals
• Usually display outward
signs of illness
• Animal may be droopy, go
off feed and water, be
restless, have a dull
haircoat
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Infectious diseases
• Caused by microorganisms
that invade the animal’s
body
• Usually contagious diseases
that the animal can pass to
another animal
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Bacteria
• Live in a wide range of
conditions
• Live on and in the bodies of all
animals
• More numerous than the cells
of the body
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Bacteria
• Many are beneficial
• Those living in the stomachs
of ruminant animals aid in
digestion
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Bacteria
• Useful in production of foods
such as cheese and
sauerkraut
• Many can be harmful
• Invade the cells of an animal’s
body
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Parasitic bacteria
• May harm the animal by
feeding off the body cells or
secreting a material known
as a toxin
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Toxin
• Substance that causes
harm to an organism
• A poison
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Harmful bacteria
• When large numbers invade,
the animal becomes ill
• Type and form of the illness
depends on the type of
bacteria that invades the
animal
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Cocci
• Round spherical shaped
bacteria
• Some forms of pneumonia
and strep are caused by this
bacteria
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Bacillus
• Rod shaped
• Single, pairs, or arranged in
chains
• Cause some serious
diseases in animals
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Bacillus
• Anthrax
• Tetanus
• Blackleg
• Intestinal coliform
• Salmonella and tuberculosis
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Spirilla
• Shaped like spirals or
corkscrews
• Very motile
• Require moist atmosphere
to live
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Spirilla
• Live very well in the
reproductive tracts of
animals
• Leptospirosis
• Vibrosis and spirochetosis
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Most bacteria
• Can be controlled by the use
of antibiotics
• Penicillin was one of the first
• Produced from extracts of
molds
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Penicillin
• Many forms are now
produced
• Very effective against
bacterial infection.
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Viruses
• Very tiny particle of matter
composed of a core of
nucleic acid and a covering
of protein that protects the
virus
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Viruses
• Have characteristics of both
living and nonliving material
• Are on the borderline
between living and non
living
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Viruses
• Made up of some of the
material found in cells but
are not cells because they
do not have a nucleus or
other cell parts.
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Viruses
• Do not grow and cannot
reproduce outside a living cell
• Once inside a living cell, virus
reproduces using energy and
materials in the invaded cell
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Viruses
• Harm cells by causing them
to burst during reproduction
• And by using material that
the cell needs to function
properly
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Virus
• Viral diseases cause the
animal to be sick by
preventing certain cells in
the body from functioning
properly
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Virus
• More difficult to treat than
bacterial diseases
• Antibiotics are not effective
against viral infections
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Viral diseases
• Foot and mouth disease
• Influenza
• Hog cholera
• Pseudorabies
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Viral diseases
• Best means of dealing with
them is prevention
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Protozoa
• Microorganism that causes
disease
• Single celled organisms that
are often parasitic
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Protozoa
• Cause harm by feeding on
cells or producing toxins
• African sleeping sickness
• Anaplasmosis
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Protozoa
• Coccidiosis
• One of the most costly
poultry diseases
• Caused diarrhea and weight
loss
August 2008
Protozoa
• Most can be controlled by
drugs
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The immune system
• Several lines of defense in
fighting disease
• Physical barriers that keep
pathogens out
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The immune system
• Nostrils are lined with hairs
that attract particles that
harbor germs before they
can enter the body
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The immune system
• Mucous membranes secrete
viscous water substance
that traps and destroys
bacteria and viruses
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The immune system
• Digestive and respiratory
systems – greatest avenue
for entry
• Some disease germs can
live in the soil for many
years
August 2008
Soil borne disease
• Animals come into contact
with the ground when they
graze
• Many pathogens are
breathed in by livestock
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Germs
• Swallowed by animals are
destroyed by digestive
enzymes
• Inhaled germs are trapped in
mucous membranes of
respiratory tract
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nd
2
line of defense
• Blood cells
• White and Red
• Red – carry oxygen and other
nutrients to other body cells
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White Blood Cells
• Are produced in the bone
marrow
• Circulate throughout the body
to get rid of worn out cells
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Phagocytes
• White blood cells that intercept
and destroy pathogens
• Also migrate to certain organs
and remain there to intercept
pathogens
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White Blood Cells
• Circulate through other body
fluids and the mucous
membranes
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Phagocytes
• Release chemicals that can
induce the production of more
white blood cells to help fight
disease
August 2008
Phagocytes
• An elevated WBC count
indicated that there are
disease organisms present in
the animal’s body and a large
number of phagocytes have
been produced to combat
them
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Lymphocytes
• Lymph glands that produce
certain WBC’s
• These cells react to foreign
substances by releasing
chemicals that kill the pathogen or
inactivate the foreign substance
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Antigens
• Substances that cause the
release of chemicals
• May be viruses, bacteria,
toxins, or other substances
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Antibodies
• The chemicals released by the
lymphocytes
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nd
2
Immune Response
• Lymphocytes become memory
cell and are ready to release
the antibody if the antigen
enters the body at a later time
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nd
2
Immune Response
• Response occurs much more
quickly
• Lasts longer than primary
response
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Immunity
• Means than an animal is
protected from catching a certain
disease
• Animal’s body is capable of
producing enough antibodies fast
enough to neutralize the disease
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Immunity
• Active or passive
• Active –animal is more or less
permanently immune
• Passive – animal is only
temporarily immune
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Immunity
• Animals are born with some
immunity
• Colostrum is rich in antibodies
• Serve the new animal until its
own immune system can take
over
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Immunity
• As the animal is exposed to more
antigens, antibodies build up
within the animal.
• Naturally acquired active
immunity results from the animal
actually contracting the disease
and recovering
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Artificial Active
• Induced by injecting antigens
into the animal
• Causes phagocytes to react
without making the animal
seriously ill
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Edward Jenner
• Late 1700’s
• Began vaccination process
• Smallpox and cow pox
• Collected material from sores
of people with cowpox
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Edward Jenner
• Injected healthy people with
material
• Became mildly ill with cow pox
• Then were immune
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Louis Pasteur
• Developed several vaccines
following Jenner’s lead
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Vaccines
• Live
• Killed or weakened strain
• Both stimulate production of
antibodies
• Killed – less dangerous when
compared to live vaccine
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Noninfectious Disease
• Not contagious
• Genetic diseases
• Caused by defects in the
genes
• Problem or disease can be
passed from parent to
offspring
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Genetic Diseases
• Cannot be spread through contact
with other animals
• Control of genetic diseases, using
good selection practices
• Avoid breeding animals that are
known to have genetic defects in
their line
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Nutritional Diseases
• Milk fever in dairy cattle
• Cows lie down and are unable
to stand
• Insufficient amount of Ca in the
bloodstream
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Milk fever
• Usually cured by injection of
Ca salts
• Effects are immediate and
dramatic
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Overeating
• Founder – horses, cattle and
sheep
• Eat too much grain
• Causes feet to become
inflamed and hooves to grow
upward and outward
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Poisoning
• Moldy feed can contain toxins
• Aflatoxins and ergot – fungi
that grow on grains
• Grazing on poisonous plants
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Disease prevention
• Vaccination
• Humans can carry disease
from one farm to another
• Many farms require plastic
boots be worn over the shoes
of visitors
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Quarantine
• Isolation of newly purchased
animals
• Government regulates
quarantine for animals coming
into the US
August 2008
Quarantine
• Many states have quarantine
periods or require health
papers for animals crossing
state lines
• Animals tested positive for
Brucellosis (Bangs) are
branded and sent to slaughter.
August 2008