TREATING LIVESTOCK AGAINST DISEASE IN WINTER
LIVER FLUKE
A parasite that causes problems, but cannot be seen, is the liver fluke. Its distribution depends on rainfall and the availability of open water sources. In very wet years cases of liver fluke can increase dramatically. Although cattle are more resilient than sheep, neither develops a good resistance to this parasite.
In South Africa, if there is high rainfall in spring and summer, conditions probably become optimal for heavy infestations of fluke in autumn. Animals get infested when they graze wet areas like wetlands of the edge of water pans. Immature flukes are ingested with the grazing and work their way through the intestines to the abdomen and then to the liver.
For the next two months they tunnel through the liver eating the tissue and growing into adults. The signs of the disease will depend on the number of infective flukes. In the first two months the animals will rapidly lose weight, show weakness and signs of blood loss. In cases of extremely high infestation there may be sudden death.
The adults move on to the bile ducts where they survive for a long time. This process destroys the normal functioning of the liver, which leads to a reduction in feed intake and metabolism, causing anaemia and lowering blood protein levels.
The worst effect on the animal occurs in late winter, when grazing is scarce and of poor quality. Bottle jaw (accumulation of fluid below the skin under the lower jaw) can be seen in affected sheep, but cattle show very few signs of disease, apart from losing condition.
Usually, the farmer only realises there is a liver fluke problem when the first animal dies. Large adult liver flukes can be seen in the bile ducts when the liver of the dead animal is cut in half. Any product that works against liver fluke can be used in late winter to treat the adult flukes. This is called strategic treatment because it gets rid of the adult flukes that produce the eggs which lead to the next generation the following spring and summer.
It takes about a month for animals to improve after treatment, if the damage to the liver was severe.
To confirm infestation in the live animal, dung must be collected and sent to the vet for tests to determine if there is a liver fluke infestation. The latest tests can identify the infestation early (from four weeks after infestation), which will be at the time when the first signs of disease are observed if the animals are severely infested.
Pneumonia is a lung infection caused by airborne bacteria and viruses. These germs are normally trapped in the membranes of the nose and windpipe and are then coughed or sneezed out. But sometimes because of wind, dust or the cold, bacteria get to the lungs, which provide a friendly environment where they can multiply and start damaging the lung tissue. At this stage, the animal’s defence system will start to fight the infection. This will show as fever. At first, no signs of disease can be observed. One to two days later the first signs will begin to show. The animal will be coughing, there will be a watery discharge from the nose, the ears will hang and the animal will start eating less.
Three to four days later, the nasal discharge becomes yellow and thick. The animal stands with a lowered head and falls behind the herd when driven.
Five to six days later the animal struggles to breathe through its nose and strains the belly and ribcage to breathe out. The pus produced by the body’s defence reaction has now permanently damaged and destroyed most of the lungs. The lungs cannot function and the animal dies because of a lack of oxygen.
If the signs are observed early enough, pneumonia can be successfully treated with an oxytetracycline like Ultratet 200 LA.