Watch out for epididymitis

This sexually transmitted disease could be the reason your lamb crop is smaller than expected. Roelof Bezuidenhout offers advice on prevention.

Rams should be vaccinated at an early stage.
Photo: Roelof Bezuidenhout

Epididymitis, sometimes called ram’s disease, is a contagious sexually transmitted disease in sheep caused by the Brucella ovis bacterium. It leads to inflammation of the testicles in rams, and infertility.

While most bulls are tested for fertility and sexually transmitted diseases, relatively few rams are tested for epididymitis, possibly because sheep farmers are less concerned about lower fertility in their flocks (and losing money) than cattle farmers are.

But considering that a ram can mate with more than 30 ewes, the cost (about R250 a test) is well worth it.

Moreover, the disease is increasing in certain areas, as not all young rams are vaccinated.

Pattern of infection
The bacteria enter the animal through any mucous membrane, then migrate to the epididymis, which is a system of tubules along the outer surface of the testes. The disease spreads mostly through direct contact between rams and ewes, and rams and rams.

Once infected, the ram’s testes become inflamed and swell before eventually hardening.

As a result, semen cannot move out of the testes. Farmers sometimes wrongly put the swelling in the scrotum down to injury.

Affected rams may still be sexually active, but fewer ewes will conceive. The infected ewes and rams will spread the disease to other rams in the flock (the rams by mounting other rams, especially when several are kept in a small camp).

Challenges
While rams should be vaccinated at two to four months of age with Rev 1 vaccine for lifelong immunity, older rams should not be vaccinated as they will then test positive for the disease and cannot be sold.

Another problem faced by farmers is that the vaccine has become scarce, or even unavailable at times, in recent years.

A better lambing rate
Take the following steps to improve your lambing rates and reduce your ram replacement costs:

  • Before buying rams, ensure they were vaccinated before four months of age;
  • Allow only tested newly bought rams into the flock with your other tested (clean) rams;
  • Carry out blood tests every year, and check for abnormalities in the testes as well as signs of infection in the semen;
  • Cull all infected rams;
  • If you breed your own rams, keep young, vaccinated rams away from adult rams;
  • Vaccinating ewes will not help; it may even result in infertility.

The author thanks Frankfort-based veterinarian Dr Andries Lessing for his assistance with this article. Email Dr Lessing at [email protected].