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ANIMAL HEALTH

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ANIMAL HEALTH The health of livestock is of great concern to farmers. Unhealthy livestock produce less, cost money and time, look horrible and cause a lot of stress. – PowerPoint PPT presentation

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Title: ANIMAL HEALTH


1
ANIMAL HEALTH
2
  • The health of livestock is of great concern to
    farmers. Unhealthy livestock produce less, cost
    money and time, look horrible and cause a lot of
    stress.

3
What is an Animal Disease?
  • An animal disease is any kind of upset in the
    normal body functioning that has an adverse
    effect on the animal.
  • This upset or deviation from normal leads to
    signs and symptoms of disease.
  • In animals symptoms can take the form of an
    increase in body temperature, an increase in the
    number of white blood cells, loss of appetite,
    mucus discharge, skin rashes, or loss of body
    weight and production

4
Diseases are caused by-
  • Micro-organisms
  • Animal parasites
  • Plant poisons
  • Nutrient deficiencies.
  • Diseases can be infectious or non-infectious.

5
The Effects of Disease on Animals
  • Disease in animals may have the following
    effects
  • Death of a small number or large number of the
    affected animals (caused by tetanus, blackleg or
    pulpy kidney).
  • Weakening and weight loss

6
  • Lower production (e.g. cows with mastitis produce
    less milk)
  • Infertility and lower calving or lambing
    percentages (caused by abortion bacteria,
    retained afterbirths etc)
  • Stunted growth (caused by internal parasites or
    nutrient deficiencies)

7
  • All diseases are expensive to the farmer and
    result in lower production from the animal and
    increased costs in production due to the cost of
    animal treatments.
  • When an animal dies, the farmer loses the capital
    cost of that animal (around 1200 for a dairy
    cow, 625 for a breeding ram etc) and he has to
    replace it. He also loses that animals future
    production.

8
Types of Diseases
  • Diseases are classified according to their cause
    as
  • Traumatic diseases caused by physical trauma e.g
    fractures, wounds and abrasions.
  • Toxic diseases are caused by poisons such as
    lead, arsenic, yew leaves, macrocarpa and
    ragwort.
  • Hereditary diseases are passed on to the
    offspring by one of the genes. A featherless
    condition in chickens is passed on in this way as
    is dwarfism in cattle.

9
  • Deficiency and/or Nutritional diseases occur from
    the lack of some essential mineral e.g. cobalt
    and copper or lack of essential vitamins e.g.
    Vitamin B12
  • Metabolic diseases occur when one section of the
    body is not working normally. Milk fever in
    cattle occurs when the calcium in the blood drops
    to a low level, usually after calving. This
    disease can be treated with an injection of
    calcium borogluconate.

10
  • Functional and /or Reproductive diseases occur
    when an organ fails to function due to some
    abnormality, as in sterility due to the blocking
    of the oviduct so that the ovum can not pass
    through. Heart failure in cows can lead to
    excess water retention.
  • Microbial diseases occur when a pathogen enters
    the animals. A pathogen can be a virus,
    bacterium, fungus or protozoan.
  • Some examples of microbial diseases are-
  • Viral disease BVD or Bovine Viral Diarrhoea.
  • Bacterial disease tuberculosis, mastitis, pulpy
    kidney.
  • Fungal disease ringworm.
  • Protozoal disease coccidiosis in chickens.

11
  • Metazoal diseases are caused by metazoans, which
    can be seen with the naked eye. These organisms
    include-
  • Flatworms - liverflukes and tapewormsRoundworms
    threadworms, barbers pole worm
  • Insects sheep blowflies
  • Ticks and other arthropods sheep keds, cattle
    ticks and lice.

12
Physical trauma on the leg of a calf.
Ostertagia
13
Primary and Secondary Causes of Disease
  • The primary cause of disease is the actual cause
    of the disease, whereas the secondary cause of
    disease assists the disease to occur. The most
    common secondary causes are-
  • Poor Nutrition this can result from
    underfeeding, either during a drought or through
    over stocking.
  • When animals are competing for food, those at the
    bottom of the pecking order receive less food.
  • Poor nutrition also comes from feeding poor
    quality feed low in essential minerals etc to
    animals.

14
  • Poor Hygiene this can occur when animals are
    intensively housed and waste management is
    inefficient e.g. housed pigs and chickens. Poor
    hygiene can also occur at vaccination, tailing,
    dehorning, drenching and in the milking shed.
  • Overcrowding this is most common in housed
    animals. Weaker animals are unable to compete
    for food and water and may become stunted.

15
  • A primary cause will cause the disease, but may
    need some help whereas a secondary cause is
    sometimes necessary for the disease to occur, but
    cannot cause the disease itself.
  • E.g. the primary cause of mastitis in dairy cows
    is an infection by bacteria.
  • The secondary causes would include poor dairy
    hygiene and poorly adjusted milking machines.
  • Lack of feed, cold weather and rough handling
    would lower the cows resistance to disease.
  • E.g. Tetanus in animals is caused by a toxin
    produced by a bacterium (primary cause).
  • For the toxin to affect animals, it needs to
    enter the body.
  • Therefore the secondary cause is a cut or wound
    to the animal.
  • Tetanus is easily controlled by the use of
    clostridial vaccines e.g. 5 in 1.
  • Primary causes of disease can be viral, fungal,
    parasitic, toxic or metabolic.

16
Infection and Disease
  • Micro-organisms cause disease by entering a host,
    multiplying and leaving the host. For a
    particular host, infection by an organism depends
    on-
  • The existence of a source of the pathogen
  • The transferral of the pathogen
  • The invasion of the host by the pathogen
    overcoming the hosts barriers to infection
  • The establishment of the pathogen within the host
    long enough for it to cause the disease.
  • Once inside the animal host, the extent of damage
    is determined by the growth of the organism, or
    by the production of toxins or enzymes that are
    able to decompose host tissue.
  • The severity of the disease is also affected by
    the environment. If the environment is
    unfavourable, then the disease will struggle to
    gain a hold over the animal.

17
  • Infective agents may enter the body in a number
    of ways.
  • 1.The most common method of entry is through the
    mouth.
  • Pathogens are swallowed with food or with
    drinking water.
  • All internal parasites e.g. roundworms and
    tapeworms, enter the body through the mouth when
    the animal eats the eggs or larvae on food or
    pasture plants (see later for more information).
  • 2. Some pathogens enter through a break in the
    skin or a wound. Wounds can be caused by
    incorrect fencing knots, needles, injuries or
    bites.
  • 3. Other pathogens may enter the body through the
    respiratory tract e.g. respiratory pneumonia.

18
TYPES OF MICROORGANISMS THAT CAUSE DISEASE
  • Micro-organisms can only be seen with the help of
    a microscope. They include viruses, bacteria,
    fungi, algae and protozoa

19
VIRUSES
  • Viruses are obligate parasites which can only
    reproduce inside the cells of another organism.
  • Viruses consist of nucleic acid (RNA or DNA)
    surrounded by a protein coat.
  • They infect a cell by incorporating their nucleic
    acid into the chromosomes of the host, initiating
    the production of more virus cells.

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21
  • Viruses are responsible for many of the following
    animal diseases, most of which are spread by
    insect vectors, contact or inhalation.
  • Influenza
  • Rabies
  • Small pox
  • Scabby mouth of sheep
  • Distemper of dogs
  • Foot and Mouth disease.

22
BACTERIA
  • Bacteria are 0.5 2.0 um in diameter and are
    normally spherical, rod-like or helical in shape.
  • They have cell walls that may be rigid or
    flexible, occur singly or in colonies, reproduce
    by binary fission and are saprophytes or
    parasites.
  • Spherical cells are called cocci (singular
    coccus).
  • Often cells do not separate during reproduction
    but remain attached to each other and thus form
    pairs of cells (as in a diplococcus), or in a
    linear chain (as in a streptococcus).
  • When a grape like cluster of cells form, they are
    known as a staphylococcus.
  • Rod shaped bacteria are termed bacilli (singular
    bacillus) and can be long or short.
  • There are several groups of spiral or curved
    shaped bacteria.

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24
  • Some bacteria are able to move. They do this by
    either swimming through liquids by means of
    flagella or by gliding in contact with a solid
    surface.
  • Flagella (singular flagellum) are long thin
    whip-like extensions from the cell wall.

25
In animals bacteria cause-
  • Brucellosis
  • Anthrax
  • Salmonellosis
  • Pulpy kidney
  • Mastitis
  • Tetanus

26
FUNGI
  • Fungi are simple eukaryotic plants consisting of
    fine branching threads or filaments called
    hyphae. They range in size from single-celled
    yeasts to multicellular mushrooms and reproduce
    asexually by spores or sexually by zygotes.
  • In animals, fungi cause-
  • Ringworm
  • Lumpy jaw.

27
PROTOZOA
  • Protozoa are single celled heterotrophs (i.e.
    they can not produce their own food). They range
    in size from 5 to 250 micrometers long. They can
    be either free living or parasitic.
  • The cell wall is not always present, and if
    present it does not contain cellulose.
  • Some groups of protozoa reproduce by binary
    fission (dividing in two) others by multiple
    fission (dividing into many parts).
  • Protozoa cause the following diseases in
    animals-
  • Coccidiosis
  • Tick fever in cattle
  • Toxoplasmosis.

28
OTHER ORGANISMS THAT CAUSE HEALTH PROBLEMS IN
ANIMALS
  • A number of other organisms cause health problems
    in animals. These are found in the following
    invertebrate classes-
  • Insects
  • Arachnids
  • Flatworms
  • Nematodes
  • Molluscs.

29
INSECTS
  • Insects are one of the most prolific and
    successful life forms on earth. Insects belong
    to the Phylum Arthopoda or jointed-feet
    organisms.
  • To be classified as an insect, an organism must
    have the following characteristics-
  • A body divided into 3 distinct sections, head,
    thorax and abdomen.
  • Three pairs of legs attached to the thorax.
    Wings may also be attached to the thorax.
  • No legs attached to the abdomen in the adult
    stage.
  • Air sacs called trachea (through which the
    organism breathes).
  • An exoskeleton (i.e. protective or supportive
    structure covering the outside of the body).
  • The main insect pests of animals are-
  • Sheep blowfly
  • Sheep ked.

30
THE LIFECYCLE OF SHEEP BLOWFLY
31
ARACHNIDS
  • Arachnids are closely related to insects. They
    also are part of the Phylum Arthopoda. They
    include ticks, mites and spiders.
  • To be classified as an arachnid, an organism must
    have the following features-
  • A body divided into two parts.
  • Four pairs of legs.
  • No antennae.
  • The most important arachnids affecting
    agriculture are ticks and mites.
  • Ticks have specialised structures that enable
    them to anchor themselves to a host.
  • They also have specialised mouthparts for
    piercing and sucking.
  • Mites have limbs that been modified for
    attachment or burrowing. Some also specialised
    mouthparts for feeding.

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  • Ticks and mites are ectoparasites (i.e. external
    parasites) of farm animals. They suck the blood
    from the host and reduce their condition. Lice
    can cause serious losses in production if left
    untreated.

34
PLATYHELMINTHS OR FLATWORMS
  • Platyhelminths are flatworms and belong to the
    Phylum Platyhelminthes. They can be free living
    or parasitic.
  • To be classified as a flatworm, an organism must
    have the following characteristics
  • Body usually flattened.
  • Definite reproductive and excretory organs.
  • A mouth leading to a simple gut.
  • Attachment organs such as suckers and hooks.
  • No circulatory or respiratory system.
  • There are two classes of Platyhelminths that are
    important internal parasites of farm animals,
    Class Tremtoda (flukes) and Class Cestoda
    (tapeworms).
  • Tapeworms and Liver Fluke are important
    endoparasites of farm animals. They cause poor
    condition

35
The Life Cycle of Liver Fluke
36
NEMATODES
  • Nematodes are also called roundworms, threadworms
    or eelworms.
  • They have the following characteristics-
  • A long, round body.
  • A non-segmented body.
  • A digestive tube with a mouth and anus.
  • In farm animals, thousands of eggs are laid by
    the female in the digestive tract of the host
    animal. The eggs then pass out with the faeces.
    In warm and moist conditions, the eggs hatch and
    develop into infective larvae. The larvae crawl
    up blades of grass, are swallowed, and
    reinfection occurs.
  • The nematodes that cause problems in farm animals
    include barbers pole worm and Nematodirus.

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38
THE DIFFERENCES BETWEEN CESTODES, TREMATODES AND
NEMATODES.
39
MOLLUSCS
  • Molluscs are soft-bodied invertebrates with
    shells.
  • With regard to animal health, a snail is part of
    the liver fluke life cycle (see earlier).

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