Contagious equine metritis

Contagious equine metritis (CEM)



Contagious equine metritis is a bacterial mating infection of horses that causes temporary infertility in mares. Humans are not infected.


Reports on the occurrence come from Europe, North and South America, Africa and Asia. Some countries, such as the USA, Canada, Australia and Japan, have reported eradication of the disease through control programmes. In 2020, a total of 192 positive cases occurred in Europe.

Host animals

Horses and other equidae

Infection route

Transmission mainly occurs through mating or artificial insemination. Indirect transmission via contaminated equipment or persons is possible.

Incubation time

2-12 days


In mares, vaginitis, cervicitis and endometritis with mucopurulent discharge and temporary infertility occur. However, striking clinical manifestations are often absent, and umrusen is often the only symptom. Infected stallions show no clinical symptoms.


A combination of systemic antibiotic therapy with local antiseptic washing is used in both the mare and the stallion. Especially in mares, freedom from pathogens is not always achieved.


Regular testing of all breeding animals before mating or semen collection and exclusion of positive animals from breeding. Hygiene management to prevent indirect transmission.

Situation in Austria

In Austria, the last positive case was reported to the European reference laboratory in 2009. Infectious equine metritis is not notifiable in Austria.

Technical information

Contagious equine metritis is a non-systemic disease of the reproductive organs that is unique to equids and is caused by Taylorella equigenitalis, an immobile, gram-negative, microaerophilic rod. Taylorella are very fastidious and reproduce very slowly. Therefore, the cultures are incubated for at least 7 days, some countries require a longer incubation period in the context of import controls.


Infected stallions are asymptomatic carriers and show no symptoms. In mares, symptoms vary widely from clear clinical signs of vaginitis, cervicitis and endometritis with mucopurulent vaginal discharge to subclinical infections. Temporary infertility lasting several weeks develops regardless of the degree of other symptoms. The general condition is usually not affected. After recovery, mares may remain carriers of germs for months and act as a source of infection.


The detection method recommended by the OIE is direct pathogen detection by cultivation. Molecular biological methods (PCR) are also permitted for investigations within the scope of Directive 92/65/EEC. Sampling, transport Swab samples must be sent to the laboratory chilled in transport medium with activated charcoal. No more than 48 hours may elapse between sampling and examination. Unrefrigerated samples must be tested within 24 hours. Samples must not be collected until at least 7 days after parenteral antibiotic therapy and 21 days after local antibiotic therapy. Sampling mare

  • Clitoral fossa
  • Clitoral sinus
  • Uterus or cervix

Sampling stallion

  • Glandular fossa
  • Urethra
  • Penis shaft (envelope site)
  • In the case of insemination stallions, a swab of pre-secretions or semen


Institut für veterinärmedizinische Untersuchungen Mödling

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