livestock ‘n’ animal health
Bruce Richards BVSc DBR MRCVS
With a primary interest in fertility, particularly bulls and optimizing dairy herd productivity, Bruce is one of six dedicated large animal vets at Paragon.
CARLISLE HOUSE, TOWNHEAD ROAD, DALSTON, CARLISLE, CUMBRIA, CA5 7JF TEL (01228 710208) FAX (01228) 711960 E-MAIL
vets@paragon.com WEB
www.paragonvet.com
Biosecurity to protect the health of a bull is a key consideration in preventing infection with Campylobacter foetus venerealis.
Campylobacter in breeding cattle by Bruce Richards BVSc DBR MRCVS
The organism Campylobacter foetus venerealis is one of the many potential causes of bovine infertility and abortions. It is transmitted from cow to bull to cow at serving.
Over the past few years, its incidence has been rising, particularly in beef suckler herds, because of a greater reliance on the use of hired bulls and because of a lack of basic biosecurity precautions.
Signs of infection • In the cow, the organism lives in the anterior vagina and cervix. From here it can invade the uterus causing an endometritis and early embryonic death or later abortions.
• The classic signs of infection within a herd would include a slight, cloudy vaginal discharge about ten days after serving, irregular and abnormally long inter- oestrus intervals and abortions at between five and seven months of gestation.
• Usually, given time, an infected cow will mount an immune response and eliminate the infection. This usually takes five or six months but occasionally may take longer. In some cases however, the endometritis and the damage that it causes
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may be so severe that the cow remains infertile and barren.
• In the bull, the organism lives in the folds and crevices of the prepuce where it can persist for life.
Diagnosis • Diagnosis of Campylobacter foetus venerealis within a herd is not always easy. Definite confirmation of infection can only be obtained by culturing the organism from either preputial or vaginal washings.
• However, due to the delicate nature of the organism, false negative results may be obtained.
• An alternative method of diagnosis is to demonstrate specific Campylobacter foetus venerealis antibodies in samples of vaginal mucus. For reliability of results, samples from a
dozen or more cows are required, which makes testing expensive.
Once the presence of Campylobacter within a herd has been confirmed options for its control or elimination are limited. • There are no licensed vaccines against this disease in the UK. If the organism can be isolated, autogenous vaccines can be produced but vaccination will only allow the disease to be controlled, and not eliminated from the herd.
• The only way of possibly eliminating this disease from an infected herd is to cull the bulls and then to use AI instead of natural service for at least three years.
Biosecurity So, given the problems that Campylobacter foetus
venerealis can cause, and the difficulty in eliminating it from an infected herd, great care should be taken to prevent its introduction. • Ideally all replacement breeding stock, both heifers and bulls, should be virgins (which can not, by definition, be infected) and should only be sourced from reputable suppliers who will guarantee this.
• Since replacement bulls are not normally virgins, they should be subjected to a thorough sheath washing using an antibiotic solution on three consecutive days in an attempt to ensure that they are not carrying Campylobacter foetus venerealis. Certainly, the use of hired bulls should be avoided. If, however, this is not possible, then sheath washing as described above becomes even more important.
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