Seminal vesiculitis is an infection involving the most predominant secondary sex glands of the breeding bull. These are paired glands which sit on the floor of the pelvis and produce the majority of the seminal fluid. This fluid is mixed with semen on ejaculation. Varying degrees of seminal vesiculitis (sv) are detected in one to 10 per cent of breeding bulls when checked for breeding soundness.
Infection is related to several factors. Young bulls on a high nutritional plane, onset of puberty, sexual aggressiveness (bulls riding one another) and housing (crowded conditions) all have been shown to increase sv occurrence. Young bulls housed together are often seen mounting one another and it is believed the infection could ascend up the urinary tract.
Concurrent diseases may result in infection developing from the hematogenous (blood-borne) route. Pneumonia, kidney infection (pyelonephritis), arthritis, and other blood-borne infections may localize in these glands.
Omphalophlebitis (also known as navel infection) may spread into the bloodstream or go up the umbilical vessels toward the urinary bladder. This close approximation with the sv may lead to scarring and infection from direct contact. The organism involved is often the same one seen in abscesses in cattle so is difficult to treat.
A congenital malformation of the duct system not allowing adequate flow of seminal fluid on ejaculation may contribute to a few of the cases but these would be hard to differentiate from true infectious causes.
Most cases of sv demonstrate no clinical signs. Cases have to be very advanced before you might see pain on urination, straining or tail swishing. The infection can descend down to the rest of the reproductive tract, causing the same infection in the testicles or epididymus, resulting in swelling and pain.
Almost all infections are detected when veterinarians perform breeding soundness exams (semen evaluations). They initially detect them when palpating the secondary sex glands. They will detect swelling and lack of lobulation to the glands. For young purebred bulls under one year of age it is an excellent idea to have your veterinarian palpate the glands. This may avoid selling your client a potential dud bull. Combine this with the same time you have the bull’s testicles measured.
In severe cases, pain on palpation with large abscesses will be detected. Your veterinarian can massage the area and collect a seminal sample to check for evidence of pus. In some low-grade cases no changes may be palpated but he/she will detect pus cells in the semen sample when examining it under the microscope.
Pus is very detrimental to semen quality and several important decisions need to be made with regards to severity of infection and prognosis for recovery. Infection in initial cases starts with enlargement, progressing to lack of lobulation in the glands and finally to adhesions or scarring in the area. Many cases in young bulls will clear up spontaneously with time.
Older bulls should be culled immediately. Other times on young bulls veterinarians elect to try antibiotics and several have proven successful over the years including erythromycin, sulfas or more recently micotil and draxxin.
The choice will depend on which ones your veterinarian has had success with. A lengthy period of treatment is necessary. In severe cases in extremely valuable yearling bulls, removal of the affected gland is possible. This procedure is performed at referral large-animal surgery clinics. Aggressive antibiotic treatment occurs pre-and post-operatively. Cases must be carefully selected and are more favourable when only one seminal vesicle is involved. Most severe cases are shipped for slaughter.
It is extremely important to note that veterinarians cannot pass a bull on semen quality if any amount of pus is detected in the sample. Therefore any clinical cases will need to be rechecked at a later date. As mentioned previously many yearlings will clear up spontaneously but it is wise to leave one to two months between rechecks. Any infections not cleared by then are unlikely to and should be culled.
Preventive measures for purebred breeders stem right back to birth. Measures to prevent navel infections are important. When housing yearlings, give them lots of space. If any bulls start getting ridden excessively they should be pulled out. A thorough semen evaluation should identify any clinical cases before they are sold.