A solid introduction to animal health, where you learn to assess animal health, explain a variety of conditions and identify appropriate treatments or responses to a range of more common complaints or illnesses.
Learn about disease classification, causes and dianosis of disease, fever and immunity, tissue repair, inflamation, cell changes and much more.
Each lesson culminates in an assignment which is submitted to the school, marked by the school's tutors and returned to you with any relevant suggestions, comments, and if necessary, extra reading.
Sample course notes:
CAUSES OF ILL HEALTH
Injury
An injury can cause disease in two different ways:
1. The animal may be injured in a way that it cannot function properly. The injury might be localised (eg. a bruise or lameness, which can be treated and put right fairly easily); or it may be severe (eg. a broken leg, which could require the animal to be destroyed). In general, treating serious injuries is a matter of economics on the farm. If the cost of treatment is greater than the value of the animal, then the animal may be best destroyed.
2. The injury may cause tissues to be exposed through wounds, which subsequently become infected by bacteria and other organisms. Examples of such diseases include blood poisoning, septic wounds, gangrene and tetanus (lockjaw).
Poisons
Poisons cause chemical processes to occur inside the animal, which lead to degeneration and death of body cells. There are two types of poisons:
1. Those present in plants eaten by animals. Some weeds which grow in pasture can be a problem and other weeds can change the flavour of milk, affecting its market value.
2. Those which are chemicals (eg. pesticides) which contaminate the animal by accident. In some cases, an ingesting excess of a useful mineral (eg. iron, fluorine, sulphur or selenium) can cause poisoning.
Hereditary Conditions
Inherited characteristics can cause certain cells in the body to degenerate. An example of this is "dwarfing" in calves
Nutritional Problems
Feeding is a factor which has a great effect on the health of farm animals, in any of the following ways:
a. Feeding too little or too much food to the animal. Too little food will cause a loss of production from the animal, and in severe cases may lead to malnutrition and death from starvation. Over feeding can lead to animals becoming over fat and unhealthy.
b. Feeding a ration which is not balanced for the particular animal's needs. Deficiencies of protein, major minerals, trace elements, vitamins, and even water; can lead to many different deficiency diseases.
c. Feeding a ration that contains a substance that is toxic to the animal.
d. Allowing the animal to eat food or to drink water that has been contaminated by bacteria or by parasites such as worms.
e. The health of the animal can be affected positively by feeding a diet that increases its resistance to bacterial disease.
Living Organisms
This is the commonest cause of ill health in animals, and the organisms involved are:
· Micro organisms - such as bacteria, fungi, viruses and protozoa.
· Parasites - as worms, ticks, lice and insects.
Micro Organisms
a. Bacteria are small organisms belonging to the plant kingdom. They consist of single cells, but when they multiply, cells often remain joined together, so that they appear to be multicellular. Bacteria reproduce in a very simple way. The bacteria enlarge, and a cell wall develops across the middle. The two new halves then separate to become two new bacteria.
This process can be completed in twenty minutes, so that if conditions are good and plenty of food is available, thousands of millions of bacteria can be produced from a single cell in 24 hours. This very rapid multiplication accounts for the rapid course of a disease, and the way in which a disease can spread throughout a herd in a short time.
Examples of diseases caused by bacteria include: Anthrax, Brucellosis, Lumpy Jaw, Mastitis and Tetanus. It must be emphasised however, that not all bacteria cause disease. Many live inside or on the skin of an animal and cause no ill effects.
b. Fungi are plants. Some are large (eg. mushrooms), and others are so small that they can only be seen under a microscope. They start from a single cell, and spread by simple division to form long threads. Fungi also produce spores which are released and spread the disease over a wide area. Ringworm is an example of a disease caused by a fungus.
c. Viruses are the smallest living organisms at present know. Viruses are a most highly infectious form of disease. They live within the cells of other living organisms, and as such are difficult to treat without also affecting the cells which they inhabit. Viruses are highly infectious.
Examples of virus diseases include: swine fever, foot and mouth disease, fowl pest, cattle plague and the common cold.
d. Protozoa are single cells, but unlike bacteria, they are animals. There are many different kinds of protozoa, some of which cause diseases in humans or in animals. In many cases, the disease is transmitted by flies or other insects.
Examples of diseases caused by protozoa include: Redwater (transmitted by ticks), East Coast Fever and Sleeping Sickness (transmitted by the tsetse fly in Africa) and malaria in humans (transmitted by insects).
Parasites
a. Worms (Helminths) are invertebrate multi cellular animals. There are two types of parasitic worms:
· Roundworms
· Flatworms (ie. Flukes or Tapeworms)
Worms often have complex life cycles, spent partly in the infested animal, and partly outside (either in a different animal, or not inside any organism). When inside an animal, they may remain in the one part of the body, or they may travel, passing through different organs.
Wherever worms are in a body, they are a foreign system, competing with the body for nourishment. They don't reproduce as fast as bacteria or fungi, but a single organism is much larger and can cause a lot of damage. They can still reproduce relatively fast, and may develop into large numbers over a relatively short period. When worms are present in an animal, they usually cause ill health either by using the food the animal would have otherwise used; or by directly damaging an organ, or tissue.
All worms are classified as endoparasites because they live inside their animal host.
b.External parasites: Ticks, Lice and other Insects are collectively called ectoparasites, because they live outside the host animal; either biting or sucking blood from the animal. This group can be divided into two:
· Arachnids - ticks and mites (adult ticks and mites have eight legs)
· Insects (adult insects have six legs)
