The immune system keeps the animal healthy. All animals and people have immune systems. The job of the immune system is to fight germs that invade the animal and could cause it to get sick. The immune system is like the animal’s own army, ready at all times to fight invaders that put the animal’s life at risk.
The immune system is found everywhere in the animal’s body. It is made up of millions of little cells that are too small for people to see with their eyes. When germs enter the animal’s body, these immune cells come from all over to attack the germs. If the cells win the battle, the animal stays healthy. If they lose the battle, the animal may get sick and need treatment. The cells are produced in the bone marrow and then spread around the body in the blood.
The immune system can recognise diseases if it has fought these diseases before. With some diseases, like contagious abortion (CA), this recognition lasts the animal’s whole life. With other diseases, however, the immune system can recognise the disease when it is present often but stops being able to recognise it when the animal hasn’t had it for a long time. Common diseases of this kind are those that ticks cause. This is one reason why animals often get sick in early dry season when there are a lot of ticks after there have been so few in wet season . Once the animal’s immune system is used to the ticks again, then the animal can often fight the tick diseases.
Livestock owners who come from areas where the disease heartwater occurs must be very careful about buying animals from other areas, because if they come from areas that do not have heartwater, the animals’ immune systems will not recognise the disease and cannot protect them and they will get sick and may even die.
It is also important to know that, like an army, the immune system is divided into different sections, each one of which has its own germs to fight. For example, one section fights redwater but it cannot fight heartwater. Only the heartwater section of the immune system can fight heartwater. This means that just because the immune system can recognise one disease does not mean it can recognise all diseases.
One way of getting an animal to have contact with a weakened form of the disease without killing the animal is vaccination. Some vaccinations must be given every year while others need only be given once in an animal’s life. Another way for the animal to develop its immune system is through the infant animal being born with some of its mother’s immune cells. Infant livestock also develop stronger immune systems if they suckle their mothers very soon after birth to drink the first milk called colostrum, which is filled with the mother’s immune cells (antibodies).
Animals that do not spend too much of their energy on getting warm or staying cool are more able to recover from disease. It is therefore wise to provide sick animals with shade and shelter from wind and rain to keep the animal warm and comfortable.
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