Animal Diseases

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Animal Diseases
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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 animals
  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 animals 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

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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

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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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2nd 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

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Phagocytes

• An elevated WBC count indicated that there are
  disease organisms present in the animals body
  and a large number of phagocytes have been
  produced to combat them

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Lymphocytes

• Lymph glands that produce certain WBCs
• 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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2nd 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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2nd 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
• Animals 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 1700s
• 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 Jenners 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

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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.