| Information sheets | | | Elsenburg infopaks | | | Animals, diseases: 4 |
Blue tongue
Afrikaans | Xhosa
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Blue tongue is season bound and occurs from midsummer through autumn and until the first occurrence of frost. The blue tongue virus usually hibernates in cattle.
Indigenous sheep breeds such as the Namaqua-afrikaner and Asiatic breeds such as the Blackhead Persian and the Karakul are less susceptible to blue tongue. European breeds, on the other hand, such as the Merino, are most susceptible. |
Blue tongue is transmitted by midges that breed in low-lying areas next to rivers and in vleie in moist and warm conditions.
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The symptoms are the following:
Fever, listlessness, lack of appetite and rapid breathing are typical of blue tongue. The mucous membranes of the eyes, nose and mouth turn red, and the lips become swollen. |
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The mucous membranes of the mouth and the tongue develop a bluish-reddish colour, and shallow sores appear on the mucous membranes of the mouth where they rub against the teeth, and also on the mucous membranes of the nose. This blue coloration of the tongue gave rise to the name "blue tongue". When the lower or upper lip is grasped with the fingers and turned down, the sores are clearly visible. |
Because of the degeneration of the muscles, such a sheep's neck often becomes twisted to one side. As a result of the infection in the mucous membranes of the nose, the nostrils are mucky and encrusted so that the sheep finds it difficult to breathe.
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Coronet infection occurs at the junction between the hoof and the skin. Consequently the sheep has a stiff gait and walks with difficulty. The legs can become so painful that the
sheep tries to walk on its knees and finally collapses and does not get up again.
Coronet infection is manifested as a red line at the junction of the hoof and the skin. It is more obvious at the back of the hoof. In order to see this infection clearly, it is necessary to wipe the hoof clean with a wet rag. The infection is more visible on a light hoof than on a dark one. |
Treatment
The animal's mouth and tongue are usually so sore that it cannot eat, and its hoofs are too painful for it to go and seek food. The first line of treatment is therefore to enclose the sheep in a small camp where shade, greenfeed and water are close at hand. They must be handled as little as possible. Antipyretics and analgesics (for example aspirin) may be administered.
Prevention
The inoculant against blue tongue consists of three parts: A, B and C. The immunity provided by blue tongue inoculant lasts for a long time and the inoculant can be administered as soon as the ewes have dropped their lambs in winter.
Lambs receive passive immunity through the colostrum of their dams and should preferably not be inoculated against blue tongue before the age of six months. Rams should receive the last inoculant two months before the mating season. Otherwise they must be inoculated after this period. Ewes should receive the last inoculant no later than three weeks before the mating season. Should there be an outbreak of blue tongue without the sheep having been inoculated, ewes that have been in lamb for at least three months, can be inoculated with reasonable safety.
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During outbreaks great care must be taken not to aid in spreading the disease. Sterilize (boil) the syringe needles after every inoculation so that the disease will not be spread from one sheep to another. Move sheep in vleie to higher-lying areas. Keep sheep under cover at night. Spray the animals with an insect-resisting agent or dip to keep midges away. |
G Brand
ELSENBURG Veterinary Services
