Animal Diseases

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

BacteriaMany are beneficial

Those living in the stomachs of ruminant animals aid in digestion

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

ToxinSubstance that causes harm to an organism

A poison

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

CocciRound spherical shaped bacteria

Some forms of pneumonia and strep are caused by this bacteria

BacillusRod shaped

Single, pairs, or arranged in chains

Cause some serious diseases in animals

BacillusAnthraxTetanusBlacklegIntestinal coliformSalmonella and tuberculosis

SpirillaShaped like spirals or corkscrews

Very motile

Require moist atmosphere to live

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

PenicillinMany forms are now produced

Very effective against bacterial infection.

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

Viral diseasesFoot and mouth disease

Influenza

Hog cholera

Pseudorabies

Viral diseasesBest means of dealing with them is prevention

ProtozoaMicroorganism that causes disease

Single celled organisms that are often parasitic

ProtozoaCause harm by feeding on cells or producing toxins

African sleeping sickness

Anaplasmosis

ProtozoaCoccidiosis

One of the most costly poultry diseases

Caused diarrhea and weight loss

ProtozoaMost can be controlled by drugs

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

White Blood CellsCirculate through other body fluids and the mucous membranes

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

AntibodiesThe chemicals released by the lymphocytes

2nd Immune ResponseLymphocytes become memory cell and are ready to release the antibody if the antigen enters the body at a later time

2nd Immune ResponseResponse occurs much more quickly

Lasts longer than primary response

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

Edward JennerInjected healthy people with material

Became mildly ill with cow pox

Then were immune

Louis PasteurDeveloped several vaccines following Jenner’s lead

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

Milk feverUsually cured by injection of Ca salts

Effects are immediate and dramatic

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

QuarantineMany states have quarantine periods or require health papers for animals crossing state linesAnimals tested positive for Brucellosis (Bangs) are branded and sent to slaughter.