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Diseases and conditions image EquiMed


Also called



“Vibrio” is a disease caused by the bacterium Campylobacter foetus, spread from cow to cow by breeding; bulls show no signs of infection, but spread it from infected cows to other cows during breeding. This sexually transmitted disease is a common cause of infertility and open cows, unless the cows are vaccinated against it or care is taken to make sure no infected animals enter the herd.

Infected bulls show no signs, even though these bacteria live in the tissue surfaces of the penis and prepuce--usually for the rest of the bull’s life. Infection in the cow may not interfere with conception, but usually kills the embryo.

The cow loses the pregnancy very early and returns to heat about 40 to 60 days after being bred. She usually shows no other signs of disease. Her inability to become pregnant again may last from 2 to 6 months as her body fights off the infection. After that, most cows build an immunity to the bacteria and can carry a pregnancy.

In some instances, however, a cow may remain infertile, or may conceive again and abort later. A few cows never completely clear up the infection--even though they eventually are able to have a live calf. These “silent” carriers serve as a source of infection the next year, infecting any bulls that breed them. If inflammation in the uterus is severe enough, the cow may be permanently infertile, but most cows recover spontaneously in about 5 months or less.

There are other sexually transmitted diseases that can cause early pregnancy loss (such as trichomiasis, so proper diagnosis is important when trying to eliminate a problem in a herd. The first sign of trouble is a high number of cows or heifers coming back into heat again after being bred. Later signs include a large number of open cows at the end of the breeding season, or an extended calving season the next year--with many late calves.

Accurate diagnosis may require lab tests to look for the bacteria in cultures of mucus samples collected from infected females or from the sheath of an infected bull, or from tissues collected from an aborted fetus. Your vet can take samples to send to a lab for culturing, and may also want to test the bulls for trichomoniasis at the same time.


  • Cows returning to heat after breeding
  • Open cows at end of breeding season


During the act of breeding, bacteria are passed from the bull into the vagina of the cow being bred, causing an infection in her reproductive tract that may persist for several weeks or months. The disease can also be passed to cows via artificial insemination.

This disease can be spread by AI breeding as well as by natural service by a bull, if semen from an infected bull is collected and used for AI. The infection can be spread to any cows inseminated with infected semen, unless the semen is treated with antibiotics before freezing or inseminating.


Vaccination of all cows and heifers that might come into contact with an infected bull can usually prevent this disease, if the animals are vaccinated at the proper time to stimulate strong immunity by the time of breeding. If vaccination is given too close to breeding, the animal may not have had time to build immunity. If given too far ahead of breeding, the immunity may be waning and the animal will not be protected.

There are several types of vaccine available, so discuss with your vet which would be best to use in your situation, and follow label recommendations for timing of the vaccinations, especially if the vaccine requires 2 doses the first year.

Timing of vaccination is very important, since the immunity produced is not long-lasting. You want to make sure the cows’ immunity is at its peak during breeding season. Most stockmen vaccinate about a month before breeding. Bulls can be vaccinated at a higher dosage than cows, to prevent the carrier state, but this should be discussed with your veterinarian.


Antibiotic treatment of an infected cow may be successful in the early stages of infection, but often this disease is not detected early. Treatment in the later stages may not be as effective. Recovery of the cow can be hastened by infusing the uterus with penicillin, and use of prostaglandins (a hormonal drug) to help the uterus flush itself.

Infected bulls can be treated, but you need to work with your veterinarian to determine the antibiotic and dosage to use, since this is an extra-label use of the antibiotic and requires a prescription. You will be working with your vet to come up with a proper diagnosis, and a plan of treatment can be made if vibrio is found to be the cause of herd infertility.

About the Author

EquiMed Staff

EquiMed staff writers team up to provide articles that require periodic updates based on evolving methods of equine healthcare. Compendia articles, core healthcare topics and more are written and updated as a group effort. Our review process includes an important veterinarian review, helping to assure the content is consistent with the latest understanding from a medical professional.