Taylorella

Contagious equine metritis (CEM) is caused by the gram-negative bacillus Taylorella equigenitalis. Transmission particularly occurs during mating; stallions latently carry the pathogen on the mucous membrane of the penis, especially in the Fossa urethralis and in the smegma of the prepuce. Transmission from infected mares to stallions is also possible. In mares, an infection leads to endometritis/cervicitis with mucopurulent vaginal discharge and to reduced fertility. Stallions show no clinical signs of the disease.
For exports, a bacteriological examination is required; within the EU, however, detection by PCR is now also recognised as a suitable test method. In Germany, there is an obligation to notify the authorities, if Taylorella equigenitalis is detected.

Taylorella (T.) asinigenitalis is closely related to T. equigenitalis, the causative agent of contagious equine metritis (CEM). The bacterium was first described in the USA, but in recent years it has also been detected in several European countries (e.g. Italy, France, Croatia, Spain, UK). Most of the time, T. asinigenitalis has mainly been detected on the genital mucosa of male donkeys, less frequently in horses. It is generally classified as apathogenic. However, in infection trials with the bacterium, it was possible to cause transient metritis and cervicitis, although the clinical picture was milder than that of an infection with T. equigenitalis. Another more pathogenic strain has also been described which led to severe, purulent endometritis after intrauterine application in mares. Remarkably, female donkeys remained asymptomatic after infection with this strain.

Apart from PCR for T. equigenitalis, an additional PCR screening for T. asinigenitalis is recommended for a comprehensive breeding soundness examination to be able to identify future outbreaks of pathogenic strains of T. asinigenitalis at an early stage.