Date post: | 07-Aug-2015 |
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DiseaseBroad definition – not being at ease or uncomfortable
Producers have a vested interest to keep their animals healthy
Healthy AnimalsGrow faster and produce more profit for their owners
Some diseases are mild, others may be severe and cause rapid death
Sick animalsUsually display outward signs of illness
Animal may be droopy, go off feed and water, be restless, have a dull haircoat
Infectious diseasesCaused by microorganisms that invade the animal’s body
Usually contagious diseases that the animal can pass to another animal
BacteriaLive in a wide range of conditionsLive on and in the bodies of all animalsMore numerous than the cells of the body
BacteriaUseful in production of foods such as cheese and sauerkraut
Many can be harmful
Invade the cells of an animal’s body
Parasitic bacteriaMay harm the animal by feeding off the body cells or secreting a material known as a toxin
Harmful bacteriaWhen large numbers invade, the animal becomes ill
Type and form of the illness depends on the type of bacteria that invades the animal
SpirillaLive very well in the reproductive tracts of animals
Leptospirosis
Vibrosis and spirochetosis
Most bacteriaCan be controlled by the use of antibiotics
Penicillin was one of the first
Produced from extracts of molds
VirusesVery tiny particle of matter composed of a core of nucleic acid and a covering of protein that protects the virus
VirusesHave characteristics of both living and nonliving material
Are on the borderline between living and non living
VirusesMade up of some of the material found in cells but are not cells because they do not have a nucleus or other cell parts.
VirusesDo not grow and cannot reproduce outside a living cell
Once inside a living cell, virus reproduces using energy and materials in the invaded cell
VirusesHarm cells by causing them to burst during reproduction
And by using material that the cell needs to function properly
VirusViral diseases cause the animal to be sick by preventing certain cells in the body from functioning properly
VirusMore difficult to treat than bacterial diseases
Antibiotics are not effective against viral infections
The immune systemSeveral lines of defense in fighting disease
Physical barriers that keep pathogens out
The immune systemNostrils are lined with hairs that attract particles that harbor germs before they can enter the body
The immune systemMucous membranes secrete viscous water substance that traps and destroys bacteria and viruses
The immune systemDigestive and respiratory systems – greatest avenue for entry
Some disease germs can live in the soil for many years
Soil borne diseaseAnimals come into contact with the ground when they graze
Many pathogens are breathed in by livestock
GermsSwallowed by animals are destroyed by digestive enzymes
Inhaled germs are trapped in mucous membranes of respiratory tract
2nd line of defenseBlood cells
White and Red
Red – carry oxygen and other nutrients to other body cells
White Blood CellsAre produced in the bone marrow
Circulate throughout the body to get rid of worn out cells
PhagocytesWhite blood cells that intercept and destroy pathogens
Also migrate to certain organs and remain there to intercept pathogens
PhagocytesRelease chemicals that can induce the production of more white blood cells to help fight disease
PhagocytesAn 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
LymphocytesLymph glands that produce certain WBC’s
These cells react to foreign substances by releasing chemicals that kill the pathogen or inactivate the foreign substance
AntigensSubstances that cause the release of chemicals
May be viruses, bacteria, toxins, or other substances
2nd Immune ResponseLymphocytes become memory cell and are ready to release the antibody if the antigen enters the body at a later time
ImmunityMeans 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
ImmunityActive or passive
Active –animal is more or less permanently immune
Passive – animal is only temporarily immune
ImmunityAnimals are born with some immunityColostrum is rich in antibodiesServe the new animal until its own immune system can take over
ImmunityAs 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
Artificial ActiveInduced by injecting antigens into the animal
Causes phagocytes to react without making the animal seriously ill
Edward JennerLate 1700’s
Began vaccination process
Smallpox and cow pox
Collected material from sores of people with cowpox
VaccinesLive Killed or weakened strainBoth stimulate production of antibodiesKilled – less dangerous when compared to live vaccine
Noninfectious DiseaseNot contagious
Genetic diseases
Caused by defects in the genes
Problem or disease can be passed from parent to offspring
Genetic DiseasesCannot be spread through contact with other animalsControl of genetic diseases, using good selection practicesAvoid breeding animals that are known to have genetic defects in their line
Nutritional DiseasesMilk fever in dairy cattle
Cows lie down and are unable to stand
Insufficient amount of Ca in the bloodstream
OvereatingFounder – horses, cattle and sheepEat too much grainCauses feet to become inflamed and hooves to grow upward and outward
PoisoningMoldy feed can contain toxins
Aflatoxins and ergot – fungi that grow on grains
Grazing on poisonous plants
Disease preventionVaccinationHumans can carry disease from one farm to anotherMany farms require plastic boots be worn over the shoes of visitors
QuarantineIsolation of newly purchased animals
Government regulates quarantine for animals coming into the US