List of six major diseases of sheep:- 1. Sheep-Pox 2. Brucellosis of Sheep 3. Tetanus 4. Listeriosis 5. Campylobactor Abortion 6. Johne’s Disease.
Disease # 1. Sheep-Pox:
Epidemiology:
Sheep-pox is a highly contagious disease. It causes a mortality of 20 to 50 per cent in animals below the age of 6 months and causes damage to the wool and skin in adults. The disease is transmissible to other goats in contact, but not to other species of animals. It, however, spreads slowly.
Symptoms:
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The disease is characterised by high fever and symptoms of pneumonia and acute enteritis. Skin lesions appear particularly in parts free from wool, notably around the eyes, inner side of the thigh, udder and under surface of the tail. The internal organs such as trachea, lungs, kidneys and intestine are also affected. The disease results in emaciation and, as already mentioned, frequent deaths of affected animals.
Treatment, Prevention and Control:
The diseased animal should be treated with palliatives. The infected litter should be burnt and the bedding changed every day. Affected animals should be kept on soft diet.
The ulcers on the skin should be washed with potassium permanganate lotion and dusted with boric acid. Strict hygienic measures, like vaccination should be adopted. In about 15 to 20 days, the animals become resistant to the disease.
Disease # 2. Brucellosis of Sheep:
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Transmission:
The mode of entry is by ingestion or via conjunctiva. The aborted foetus, vaginal discharge and milk from infected sheep contain a large number of organisms.
Symptoms:
In infected sheep, state of abortion may occur followed by a quiescent period during which a few abortions occur. The aborted animals do not breed. After 2 years or more another abortion storm is likely to occur.
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Diagnosis, Treatment and Control:
It is not possible to diagnose brucellosis on the basis of symptoms alone. The suspicion is aroused when humans in contact suffer from undulant fever and there is poor breeding record in sheep herd and evidence of mastitis. The diagnosis can be done by the isolation of organisms and by serological tests.
Treatment is based on proper hygiene, vaccination, testing and disposal. Good management practice; essential.
Disease # 3. Tetanus:
This is an infectious, non-febrile disease of animals and men and is characterised by spasmodic tetany and hyperaesthesia. This disease is prevalent all over the world.
Transmission:
Infection takes place by contamination of wounds. Deep punctured wounds provide favourable conditions for the spores to germinate, multiply and produce toxin which is subsequently absorbed in the animal body. The microorganism is present in soil and in animal faeces, and is carried into the wound by a penetrating object.
Symptoms:
Tetanus affects many species of domesticated animals but occurs particularly in horses and lambs; less frequently in adult sheep, goats, cattle, pigs, dogs and cats. The initial symptoms are mild stiffness and an unwillingness to move.
More severe symptoms develop after 12-24 hours of infection which are stiffness of limbs, neck, head, tail, and twitching of muscles. Mastication becomes very difficult because mouth cannot be opened, hence the name lockjaw.
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Treatment:
The treatment is carried out by first injecting antitoxin, then treating the wound. Penicillin parenterally is beneficial. Muscular relaxation is achieved by injection of relaxants. The animal should be kept in a dark room and fed with the help of stomach tube.
Disease # 4. Listeriosis:
Transmission:
The infectious organisms are excreted in the faeces, urine, aborted foetus, uterine discharge and milk of infected animals. The blood sucking arthropods may spread infection since organisms have been isolated from cattle ticks and tabanid flies.
Symptoms:
In farm animals, the disease occurs towards the end of winter or early spring. The first signs of meningoencephalitis are stiffness of neck, incoordinated movement of limbs and tendency to move in circles or to lean against a fence or wall. Abortions in cattle usually occur after 4-8 months of pregnancy and at a comparatively later stage in sheep.
Treatment:
Tetracyclines are very effective in meningoencephalities of cattle, less so in sheep. The recovery rate depends on the speed with which the treatment is commenced.
Disease # 5. Campylobactor Abortion (Vibriosis):
Transmission:
Transmission occurs by coitus. The organism survives in low temperature used during semen storage.
Symptoms:
Among sheep the disease is characterised by abortion, occurring towards the end of gestation. Usually abortion is preceded by vaginal discharge for several days. The aborted foetus is edematous with petechial haemorrhages on serous surfaces and necrotic foci in the liver.
Treatment:
Abortion rate can be reduced by antibiotic therapy, and particularly by using chlorotetracycline and concurrently with the development of specific immunity.
Disease # 6. Johne’s Disease:
Johne’s disease is a specific chronic contagious enteritis of cattle, sheep, goat, buffaloes and occasionally of pigs.
Transmission:
Under natural conditions, the disease spreads by ingestion of feed and water contaminated by the faeces of infected animals. The infection occurs mostly in the early month of life. The incubation period extends from 12 months to several years.
Treatment:
The organisms are more resistant to chemotherapeutic agents in vitro than Mycotuberculosis. Because of this, the practical utility of treatment in clinical cases is poor.