Brucella ovis

Brucella ovis

Changed on: 25.08.2021

Animal disease categories: B D E


Infections with the bacterium Brucella ovis cause inflammation of the testicles and epididymis in rams. Humans cannot contract this bacterium.


Nearly worldwide in all sheep-rich regions

Host animals

Sheep, deer

Mode of transmission

Transmission occurs via direct contact (droplet infection) from infected ram to ram or indirectly during mating via female sheep. After colonisation of the kidneys, excretion can also occur via the urine.

Incubation period

3-17 weeks


In rams, there are unilateral or, more rarely, bilateral epididymitis. In pregnant ewes, abortions and increased lamb mortality may occur.

Therapy and hygiene measures

A specific therapy is not possible. Infected rams should be excluded from breeding or the flock as soon as possible and the flock and contact animals should be clinically and serologically examined.


B. ovis is generally introduced into a flock via infected sheep or semen. Therefore, clinical examination (palpation of the scrotum) and serological screening (detection of antibodies) of potential breeding rams or rams of unknown health status prior to introduction into the flock are the most important preventive measures against the spread of the pathogen. Infections in ewes can be prevented by controlling B. ovis in rams.

Situation in Austria

Individual cases occur only sporadically. There are appropriate monitoring and control programmes. Positive rams must be excluded from breeding by slaughter or castration and the affected stock must be re-examined.

Professional information

The reservoir for B. ovis infections is chronically infected rams. The pathogen may persist in testes, epididymis accessory sex glands or kidneys and be shed intermittently for years.

After mating with an infected ram, the pathogen may survive in the vaginal secretions of the female sheep and be transmitted to an uninfected ram during the next mating. Females usually shed the pathogen after a few months, thus contributing only temporarily to further spread in the flock. Abortions or the birth of weak lambs due to placentitis of the infected ewe occur rather rarely. Young rams, even though they have not yet been used for mating, can become infected from infected rams through social interaction in the ram flock (sniffing urine or semen, or ranking fights with rectal copulation).Rams from flocks of unknown status should not be kept with other rams or used for breeding. Ewes recently mated by infected rams pose a potential risk of infection to healthy rams.


The majority of B. ovis infections are asymptomatic or changes (genital lesions) only become clinically visible at a late stage of infection. Aries become clinically conspicuous by unilateral, rarely bilateral palpable changes of the epididymis (epidiymitis). An economic loss due to changes in the breeding parameters in the flock often only becomes visible in intensive sheep farming.


Indirect methods:

  • Serological detection of B. ovis antibodies(ELISA, complement fixation reaction).

Direct methods:

  • Bacteriological: culture test from organ material, semen or swab samples on selective media
  • Molecular biological: genome detection by PCR

Contact, Forms

Institute for Veterinary Investigations Mödling (National Reference Laboratory)Robert Koch-Gasse 172340 MödlingTel: +43 50 555-38112Fax: +43 50 555-38529E-Mail:

Institute for Veterinary Investigations LinzWieningerstraße84020 LinzTel: +43 50 555-45111Fax: + 43 50 555-45109E-Mail:

Institute for Veterinary Investigations InnsbruckTechnikerstraße706020 InnsbruckTel: +43 50 555-71111Fax: +43 50 555-71333E-Mail:

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