sheep

Tetanus (lockjaw)

Tetanus is a disease caused by Clostridium tetani, an organism commonly found in the soil. It is much more prevalent on farms where horses have been kept. The spores live in the soil for years and can present a continuing disease problem on some farms. The organism can infect sheep through wounds from shearing, docking, castration, or vaccination. The organism also can be introduced into the reproductive tract by unsanitary humans who assist ewes during lambing.

Stiffness of limbs and difficulty in moving or walking are commonly the most noticeable symptoms of tetanus. These early symptoms are similar to those of white muscle disease, polyarthritis, erysipelas, and navel ill. Affected animals are easily excited and muscle spasms can occur. Later, the jaw may become rigid such that the animal cannot open its mouth. Spasms of the neck and back muscles cause extension of the head and neck. The hind legs are rigid and extended backwards. Affected lambs may fall when excited.

Few lambs recover from this disorder, and there is no satisfactory treatment. Where tetanus is a problem, it is important to take preventive measures. Elastrator bands are not recommended for tail-docking and castration in areas where tetanus is an annual problem. All surgical procedures should be performed under strict sanitation.

If infection is likely, vaccinating with tetanus antitoxin provides protection for about two weeks. Vaccinate at castration and/or tail-docking. When tetanus is an annual problem, generally the best protection is to immunize the entire flock with the toxoid. Ewes can be immunized with two injections 30 to 60 days apart. Ewes also should receive an annual booster just before lambing, though this injection can be incorporated into the aforementioned two injections.