Epididymitis in Sheep
There are not different strains of one bacteria causing this disease, but two different bacteria causing almost identical symptoms in rams. In western Canada the principle bacteria implicated are Brucella ovis and Actinobacillus seminis. In Ontario there have been very few isolations of B. ovis, but epididymitis is still a problem. In this province the bacteria thought to be the cause is Actinobacillus seminis. However, the result is the same, a chronic infection of the epididymis and testes with lowered fertility of the ram.
In the early stage, often overlooked, there is a swelling of the epididymis, which may or may not be painful. This lasts a few days, then subsides. As the disease progresses the texture of the testes changes to soft and then harder than normal. A normal testes should feel the same under finger pressure as pressing the muscle at the base of your thumb. Veterinarians, in a breeding soundness examination of a ram, will measure the scrotal circumference at the widest point. In a chronic epididymitis case this will be less than expected for that ram's body weight, age and season of the year. In many cases only one testicle is affected, the difference in size is easy to see. If there is a doubt, a semen examination will often show that there is a reduced semen production. If the ram is positive to these tests, it should be considered subfertile or infertile and be culled. This examination of all flock rams should be carried out prior to each breeding season. Even a subfertile ram can seriously affect the lambing percentage in a flock.
There is no treatment for these conditions. Ram management is important. Young rams should be run separate to older rams, and wherever possible only used to breed first lamb ewes. In some countries vaccines are used to protect against B. ovis with some success, but with unwanted side-effects. These vaccines are not available in Canada.
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