By Roelof Bezuidenhout
Epididymitis in sheep, also called ram’s disease, is a chronic infection of the epididymis – a long, tightly coiled tube on the back and lower side of the testes in which sperm is stored and transported. The infection is caused by the Brucella ovis bacterium.
Epididymitis leads to reduced fertility, so it can seriously affect your lambing rates.
The bacteria spread primarily through the semen of infected rams, but also through direct contact. They enter the animal through any mucous membrane and migrate to the epididymis. Ewes are also infected, but in most cases the infection is temporary and doesn’t cause long-term issues.
Once infected, the ram’s testes become inflamed, and initially show swelling before the epididymis eventually hardens. This hardening blocks the movement of semen, leading to reduced fertility. Farmers sometimes wrongly attribute scrotal swelling to injury, overlooking the underlying infection.
Infected rams may still show sexual activity, but fewer ewes will conceive. Meanwhile, the rams continue to spread the disease to others in the flock. Transmission is especially likely when rams mount one another – a common behaviour when rams are kept together in small camps.
A blood test for antibodies costs only a few hundred rand, and considering that a ram can mate with more than 30 ewes, investing in testing your rams makes good economic sense.
There is no treatment
Young rams should be inoculated with the Rev 1 vaccine between two and four months of age to ensure life-long immunity.
Cases of epididymitis are increasing in some areas, partly due to the vaccine not always being available, and the fact that not all young rams are being vaccinated.
Many older rams may not be vaccinated, as a false-positive result in a blood test would mean they cannot be sold.
No breed of sheep appears to be less susceptible to the bacterium than others.
Prevention
- Only buy rams that were vaccinated before four months of age.
- Introduce new rams to your flock only if they have tested negative and only run them with other tested (clean) rams.
- Conduct annual blood tests and routinely check for abnormalities in the testes and signs of infection.
- Cull all infected rams immediately.
- If you breed your own rams, keep young, vaccinated rams separate from adult rams.
- Do not vaccinate ewes – it won’t help and may even cause infertility.
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 | Roelof Bezuidenhout is a fourth-generation wool, mohair, mutton and game farmer and freelance journalist. Attended Free State University, majoring in animal husbandry and pasture science. Other interests include agricultural extension and rural development. |
