Campylobacteriosis in Cows: Infertility, Early Embryo Loss, and Prevention

Campylobacteriosis in cows, also called bovine genital campylobacteriosis or vibriosis, is a contagious reproductive disease caused by Campylobacter fetus organisms. In cattle, it is mainly spread during breeding, so it matters most in herds using natural service. The disease is known for causing infertility, early embryonic death, repeat breeding, and a prolonged calving season rather than obvious whole-body illness.

Many cows with this infection appear healthy. They usually keep eating, walking, and acting normally. That is why the condition can be frustrating for cattle producers and pet parents caring for small family herds. The first sign may be that cows do not stay pregnant, pregnancy rates drop, or more cows than expected return to estrus after breeding.

The bacteria can persist in the reproductive tract, especially in bulls that carry the organism in the prepuce without visible illness or abnormal semen. Older bulls are more likely to become long-term carriers. In cows, infection may eventually clear, but fertility losses can continue long enough to affect the breeding season and calf crop.

Because several reproductive diseases can look similar, your vet will usually consider campylobacteriosis alongside trichomoniasis, leptospirosis, BVD, nutritional issues, and other causes of pregnancy loss.

Campylobacteriosis in cows is caused by Campylobacter fetus venerealis or Campylobacter fetus fetus. These are fragile bacteria outside the animal, but they spread efficiently during breeding. The main route is venereal transmission, especially when an infected bull breeds susceptible cows or heifers.

Bulls are central to herd spread. Older bulls are more likely to become chronic carriers because deeper preputial crypts give the bacteria a place to persist. These bulls usually look healthy and can continue breeding normally while spreading infection. Younger bulls may clear infection more readily, but they can still transmit the organism after breeding infected females.

Cows can also carry the organism in the reproductive tract for variable periods. Some clear infection relatively quickly, while others remain infected for months or longer. Even when a cow eventually conceives, the vagina may stay infected during pregnancy, which helps maintain infection pressure in the herd.

Less commonly, spread can happen through contaminated semen used for artificial insemination, or by contaminated instruments and bedding. Risk tends to rise when herds use shared, rented, or recently purchased mature bulls, have limited breeding records, or bring in replacement animals without a quarantine and testing plan.

Diagnosis usually starts with the herd story. Your vet will look at breeding dates, return-to-estrus patterns, pregnancy-check results, abortion history, and whether natural service bulls were used. A herd with repeat breeding, low conception rates, and a prolonged calving season raises concern for venereal disease.

Laboratory testing is important because campylobacteriosis can look like several other reproductive problems. Depending on the case, your vet may collect vaginal mucus or cervical samples from cows, or preputial washings/scrapings from bulls. Merck Veterinary Manual lists vaginal mucus agglutination testing, ELISA, immunofluorescence, and culture as diagnostic options. Many veterinary diagnostic laboratories also offer PCR testing on preputial or vaginal wash samples.

Testing often works best as a herd-level investigation, not a single-animal guess. Your vet may recommend sampling multiple cows, especially recently exposed or repeat-breeding animals, and may also test bulls because they can be silent carriers. Other diseases such as trichomoniasis, leptospirosis, BVD, and nutritional or management causes of infertility may need to be ruled out at the same time.

Typical 2025-2026 U.S. lab fees are often around $18 to $40 for culture and $35 to $60 for PCR per sample, with additional costs for farm calls, reproductive exams, shipping, and herd consultation. Total herd workups commonly land in the low hundreds to low thousands of dollars, depending on how many animals are sampled.

Prevention focuses on breeding biosecurity. The biggest risk often comes from introducing an infected bull. Work with your vet before buying, borrowing, leasing, or sharing bulls. Mature non-virgin bulls deserve extra caution because they are more likely to carry the organism long term. When possible, source breeding animals from herds with strong reproductive health programs and no known history of venereal disease.

A practical prevention plan may include quarantine of new arrivals, testing when indicated, and avoiding commingling with outside breeding animals. University of Wisconsin Extension notes that using virgin bulls for one breeding season can greatly reduce establishment of campylobacteriosis in a herd. If your operation can support it, artificial insemination is one of the most effective ways to limit venereal spread.

Vaccination is another common prevention tool. Merck Veterinary Manual states that outbreaks can be controlled by vaccination or artificial insemination. Vaccine timing and product choice vary by herd, breeding season, and label directions, so your vet should tailor the schedule. Vaccination helps reduce herd impact, but it works best when paired with bull management and sound biosecurity rather than used alone.

Good records matter. Track breeding dates, returns to heat, pregnancy-check results, abortions, and calving distribution. Those details help your vet spot a problem early, before one carrier bull affects a large part of the herd.