Previous Page Table of Contents Next Page

Chapter 2: The animal body

Unit 3: Organs and systems of the body
Unit 4: Body temperature
Unit 5: Appearance of the healthy animal
Unit 6: Spread of disease

Unit 3: Organs and systems of the body

The body is made up of many, many millions of cells which you can not see unless you use a microscope. Special cells come together to make an organ.

An organ is a complex structure within the body. It has a special job or jobs to do.

A body system consists of a number of organs which work together to carry out a special job.

The animal body is made of 9 systems:

Musculo-skeletal system
Digestive system
Circulatory system
Respiratory system
Urinary system
Nervous system
Sensory system
Reproductive system
Lympho-reticular system

Learning objectives

After studying this unit you should know:

1 The various organs of the body.
2 The position of the main organs within the body.
3 The structure of the body systems.
4 How the systems work.

The organs of the body

An organ is a complex structure with a special job or a number of jobs to do. For example:

· The eye is the organ of sight.
· The kidneys are organs which get rid of water and poisonous materials from the body as urine.
· The liver has many jobs and is involved in more than one system.

Various organs are grouped together to form a body system which carries out a special job.

System of the Body

Organs in the Body

Job or function


muscle (meat) bones

Support and move the body


stomach, liver, intestine, pancreas

Digest and absorb feed


heart, blood vessels

The brood carries substances around the body


muzzle, windpipe, lungs



kidneys, bladder

Get rid of poisons and waste (urine)


brain, nerves spinal cord

Pass messages around the body, control the body


eyes, ears, nose skin

Sense and detect things outside the body


testes, penis ovaries, uterus, vagina, vulva, udder

To produce and feed young


lymph nodes, spleen

Protect against infectious diseases, produce blood

The musculo-skeletal system

This system consists of the bones and the muscles (meat).The bones form the skeleton which is the framework within the body. It carries weight and supports the body.

Bones are connected together so they can move. The places where this happens are called joints. The bones are held together at the joints by elastic strands called ligaments. Between the bones is a softer material called cartilage (gristle) which cushions the bones at the joints when the body moves. Bones are very hard and contain minerals. Each bone has a name such as the scapula (shoulder blade) and skull (head). There are about 200 bones in the body.

Muscles are joined at both ends to the bones. The muscles are the meat of the body and when they contract (shorten) or relax (lengthen) they make the bones move.

If you bend your arm you can see and feel the muscles in your arm working.

The digestive system

The digestive system consists of the teeth, mouth, gullet (oesophagus), stomach, liver, intestine, pancreas, and rectum.

Digestion begins in the mouth where feed is broken down into small pieces by the teeth and mixed with saliva before being swallowed.

In the stomach feed is mixed with the juices to form a soft paste. This then passes into the intestine where bile from the liver and juices from the pancreas are added. The action of these juices is to break down the feed and allow the nourishment it contains to be absorbed by the blood in the walls of the intestine. Waste matter collects in the rectum and passes out of the body through the anus (or cloaca in birds).

The digestive system

The circulatory system and blood

The organs of the circulatory system are the heart and the blood vessels (tubes). The heart is found in the chest cavity. It is a muscular pump which sends blood around the body.

The blood vessels which carry blood away from the heart are called arteries. Blood returns to the heart in veins. Joining the arteries and veins is a fine network of small tubes called capillaries. The capillaries pass through every part of the body.

When the heart beats its muscles contract and sends blood out through the arteries. When the heart relaxes blood flows into it from the veins.

Every time the heart beats it sends a pulse along the arteries. You can feel it at certain points on the body. By feeling the pulse we can count the rate at which the heart beats (see Unit 5). You can feel your pulse on your wrist.

The respiratory system

Respiration (breathing) consists of inspiration (breathing in) and expiration (breathing out).

There are two lungs which are found in the chest protected by the bony cage of the ribs. The windpipe carries air from the nostrils to the lungs which are spongy because of air spaces in them. As the animal breathes, air moves in and out of the lungs. Inside the lungs oxygen needed by the body passes into the blood in the walls of the lungs and water and carbon dioxide pass out of the blood into the air which is then breathed out.

The respiratory system

The urinary system

The main organs are the two kidneys, which lie against the backbone, and the bladder.

Waste materials and water are taken out of the blood in the kidneys. This forms urine. Urine collects in the bladder then passes out of the body.

Nervous system and sensory system

The bones of the skull and backbone protect the soft brain and spinal cord. Fibres called nerves pass from the brain and spinal cord to all parts of the

Messages pass from the various parts of the body along the nerves to the brain. The brain sends a message back telling the different parts of the body what to do.

The brain controls the body.

Nervous system

The brain also controls the senses, the sense organs are:

· the eyes for sight
· the ears for hearing
· the nose for smell
· the tongue for taste
· the skin for touch

Reproductive system (breeding)

The male reproductive organs, the testicles, lie in the scrotum behind the penis. The testicles produce sperm which are contained in the fluid semen. A tube passes from each testicle and joins to form a tube which runs down the centre of the penis.

In the bird the testicles are inside the body.

Reproductive and urinary organs of the male

The female reproductive organ consist of two ovaries, one in each side of the lower abdomen. The ovaries produce eggs which pass into the uterus (or womb). Below the uterus is the vagina which opens to the outside surrounded by the vulva. After birth the young are fed on milk produced by the udder.

Female reproductive and urinary system

During mating (mounting) sperm passes from the male into the uterus and joins with the eggs there. When the sperm joins the egg it forms the embryo which develops into the young animal inside the uterus.

Reproduction is controlled by hormones (chemical messengers) which are carried in the blood to the different organs.
These hormones control:

· Puberty of the animal
· Production of eggs
· Birth
· Production of semen
· Development of the embryo
· Milk production

Lympho-reticular system

Lymph is a colourless fluid which passes out of the blood into a network of fine tubes called the lymphatic system. It passes through the lymph nodes, where germs are filtered out and killed, before it is returned to the veins. The lymph nodes and spleen also produce special blood cells which protect the body against disease. Sometimes when an animal is infected the lymph nodes become swollen and can be felt beneath the skin (see Unit 75).

Unit 4: Body temperature

The body must be kept at a constant temperature, within a small range, in order for all of the systems to work properly. This is the normal body temperature.

A change in the temperature of the body is a sign of ill health.

Learning objectives

After studying this unit you should understand what is meant by:

1 The normal body temperature.
2 High body temperature.
3 Low body temperature.
4 How to take the body temperature.
5 What is the normal body temperature of different animals.

The normal body temperature

The body can only work properly at a certain temperature. The animal body maintains itself at a constant temperature, within a small range, in order for the systems to work properly. This normal body temperature is different in different types of animals.

There are a number of ways by which animals control the temperature of the body:

· Hair, wool, walking, running, shivering and the burning of energy in feed keep the body warm.

· Sweating, panting, wallowing in mud, and lying in the shade cool the body.

Measuring body temperature

We use a thermometer to measure the temperature of the body. The unit of measurement is degrees centigrade (°C). The normal temperature of your body is 37°C. We measure the body temperature of animals by placing a thermometer in the anus.

The thermometer

· Look at your thermometer. Notice the silver line of the mercury inside it and the scale with numbers marked along it.

· Before you use it you must make sure that the mercury level is below 35°C. If it is not, shake the thermometer to make the level go down.

· Every time you use the thermometer clean it with cold water and soap or disinfect it afterwards.

Do not wash the thermometer in hot water as this will burst it. Do not leave your thermometer in the sun as this may burst it. Carry the thermometer in a case in your pocket or bag. Do not use your veterinary thermometer for people.


How to take the body temperature of animals

· Control the animal.

· Move the tail to the side.

· Put the thermometer gently into the anus, as far as possible.

· Hold the thermometer at an angle so that it touches the wall of the rectum. Keep a firm grip on the thermometer, if the animal defecates or coughs the thermometer could come out or go into the rectum.

· Hold the thermometer in place for half a minute. If you do not have a watch count slowly up to 30 (one, two, three, ............ thirty).

· Remove the thermometer and wipe it if necessary and read it. Do not touch the bulb as this could change the reading.

How to take the body temperature of animals

Normal body temperatures


Normal Temperature °C

Normal Animal

Temperature °C













Llama, alpaca












Body temperatures may be 1°C above or below these temperatures.

* The camel's body temperature will vary with the time of day and water availability. When a camel is watered daily its body temperature rises from 36.5°C in the morning to 39.5°C at noon, if the animal has no water, the temperature range is 34.5°C to 41°C.

If you suspect that the animal has a high temperature use your thermometer to check it. Remember that a high temperature is one sign of ill health. When an animal has a high temperature it has a fever.

Unit 5: Appearance of the healthy animal

You should be able to distinguish between the sick and the healthy animal. Identifying the signs of ill health in livestock will mean that you can:

· Give first aid and treat ill animals quickly
· Prevent the spread of disease to other animals
· Recognise any problems in animals offered for sale
· Recognise any signs of health problems in animals to be used for breeding

Learning objectives

After studying this unit you should know:

1 The characteristics of the healthy animal.
2 Recognise the signs of ill health.

Appearance of the animal

The healthy animal is alert and aware of its surroundings. It is active and holds its head up watching what is happening around it. It should stand on all of its feet. The separation of an animal from the others in its group is often a sign of a health problem.

An animal which is not interested in its surroundings and does not want to move has health problems.

Movement (gait)

The healthy animal will walk easily and steadily with all of its feet taking its weight. Steps should be regular. Irregular movement results from pain in the feet or limbs.

Horses normally stand during the day. If you go near an animal that is lying down it should stand up quickly otherwise it has health problems.


The eyes should be bright and alert with no discharge at the corners.


Most animals have erect ears which move in the direction of any sound. Ear movements will also be quick to get rid of flies, he body temperature of the pig can be checked by touching the ear when an unusually high temperature will be noticed.

Nose and Muzzle

The nose should be clean with no discharge. In cattle and buffalo the muzzle should be moist not dry. In sheep and goats the nose should be cool and dry. Healthy animals frequently lick their noses with their tongues.

Nose and Muzzle


There should be no saliva dripping from the mouth. If chewing is slow or incomplete there must be a problem with the teeth.

The coat

In short-haired animals, e.g. goat and cattle, the hair or coat of the healthy animal will be smooth and shiny. Healthy cattle, buffalo and their calves lick their coat and the lick marks will show. Horses should not sweat when resting.

The coat

In poultry the feathers should be smooth and glossy and not ruffled. In pigs a curly tail is a sign of good health while a scaly skin points to health problems.


If a horse, cow or buffalo keeps looking at its flanks or kicks at its belly it has a pain in the stomach.


Breathing should be smooth and regular at rest. Remember that movement and hot weather will increase the rate of breathing. If the animal is resting in the shade it should be difficult to notice the chest moving as it breathes.


Taking the pulse (see unit 3) is important when examining an animal. In man the pulse can be easily taken but in animals it is more difficult and requires practice.

· In sheep and goats you can feel the pulse on the inside of the top of the back leg. The rate of the pulse is 70 - 130 per minute in the adult.

· The pulse of cattle is taken at a point on the underside of the base of the tail, the normal rate is 40 - 80 per minute in the adult. In buffalo the pulse rate is 40 - 60 per minute.

· The pulse of the horse is taken on the inside of the cheek. The normal rate is 35 - 40 per minute.

· The pulse of the camel is taken at a point on the underside of the root of the tail. The normal rate is 35 - 45 beats per minute.

Remember that the pulse will be higher in the young animal. To take the pulse you should feel for it with the first two fingers of the hand.

In the llama, alpaca and the pig there is no point at which the pulse can be taken. In these animals the beat of the heart itself must be felt for.

Droppings or dung

The droppings of the healthy animal will be firm. Very soft droppings (diarrhoea) is a sign of ill health. If the animal has difficulty in defecating (constipation) this is also a bad health sign.


The urine should be clear and the animal show no signs of pain or difficulty in urinating. Horses, mules and donkeys can have thick yellow urine which is normal.

Appetite and rumination

The animal should eat and drink normally. Failure to eat is an obvious sign of ill health. If feed is available the healthy animal will have a full belly. Pigs will naturally rush at their feed, if they do not something is wrong. Sheep, goats, cattle, buffalo and camels chew the cud (ruminate) for 6 to 8 hours each day. It is a sign of ill health when these animals stop ruminating.


In the milking animal a sudden change in the amount of milk produced can mean a health problem. Any sign of blood or other matter in the milk points to infection in the udder. There should be no swelling of the udder and no sign of pain when it is touched. There should be no injury to the teat.

Body temperature

If you suspect that an animal is sick you should take its temperature (see Unit 4).Taking the temperature may show a higher than normal body temperature which is sign of an infection.

A good PAHCW learns to:

· Carefully watch the normal animal at all times and learn how it behaves.

· You will then recognise when something is not right.

· Question the person looking after the animals to discover if he or she has noticed anything different about them.

· Remember you must first watch the animals from a distance, talk to the person who looks after them, and then check the animals. You will then be able to decide what to do next.

Unit 6: Spread of disease

Disease occurs when something goes wrong with the body or part of the, body.
Diseases can be caused by germs, bad feed, chemicals or injuries.
Diseases caused by germs are called infectious diseases.
An infectious disease can spread from one animal to another.

Learning objectives

After studying this unit you should know:

1 How animals become ill.
2 What is meant by the spread of disease.
3 What is an infectious disease.
4 What is a non-infectious disease.
5 How to prevent the spread of disease.

The main causes of disease

Disease can be classified as acute or chronic. An acute disease starts quickly and lasts for a short period when the animal either recovers or dies. A chronic disease lasts for a long time and weakens the animal. Diseases are said to be infectious (will spread from one animal to another) or noninfectious (will not spread from one animal to another).

Non-infectious diseases can be caused by poor feed and the lack of minerals, salts and vitamins that the body needs. Non-infectious disease can also be caused by poisoning with chemicals or plants, by cuts, burns and broken bones. Some diseases pass from the parent to the young (hereditary).

Many non-infectious diseases are chronic but they can be acute. They can cause large losses of meat, milk and wool. Working (draught) animals do not work well and the rate of reproduction can be low with the young being born dead or dying before they are weaned. Chronic diseases are often thought to be "normal" but when the cause is known and eliminated production can be greatly increased.

Infectious diseases are caused when the body is attacked by tiny living germs.

The spread of disease

Infectious diseases can be spread by:

· Direct contact between animals.
· Germs in feed and water.
· By faeces and urine from sick animals.
· By flies, ticks, lice and fleas.
· By dirty housing or shelters.
· Young and old animals become infected more easily.

Preventing infectious diseases

· Animals, like humans, must be clean in order to be healthy. The animal must be provided with clean feed, water, bedding and shelter.
· Sick animals should be kept separate from the others.
· Some diseases can be cured by drugs.
· Vaccination can protect animals against some diseases.
· Dead animals and waste should be disposed of.


· The spread of disease can be avoided by good livestock management. Keeping animals together increases the chance of disease spreading by contact. New livestock should be kept separate from the others for two weeks so they can be checked for signs of disease.

· Avoid mixing herds. Try to keep herds separate at watering and feeding points.

· You should separate and isolate any animal which shows signs of disease.

Preventing non-infectious diseases

The chronic non-infectious disease may not be recognised as a disease. The affected animals may not die but will not produce as much milk, meat or wool, or work as well as could be expected.

If we continually look for ways of improving feed, water, mineral and vitamin supplies we will find the way to control the non-infectious diseases. This will lead to greater production of wool, meat and milk, draught animals will be stronger and more young will be produced. Poultry will produce more eggs and get fatter.

Previous Page Top of Page Next Page