Equis ISSN 2398-2977

Taylorella equigenitalis

Synonym(s): T. equigenitalis Contagious equine metritis organism CEMO

Contributor(s): Sarah Binns, Susan Dawson, Prof Peter Timoney, Richard Walker




  • Genus:Taylorella.
  • Species:equigenitalis.

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Clinical Effects



  • Stallions: urethral fossa, urethral sinus, prepuce and urethra.
  • Recovered mares: clitoral fossa and sinuses and the uterus in some mares .


  • Usually sexual.
  • Can also be spread on fomites, eg veterinary instruments.

Pathological effects

  • Recovered animals are resistant to disease for several months, but may be re-infected.
  • Antibody titers are of short duration and are unrelated to carrier status.
  • Sexual transmission to mare   →   endometritis   Vagina: endometritis - endoscopy  within a few days   Uterus: contagious equine metritis  .
  • T. equigenitalisdamages uterine epithelium   →   covered by neutrophilic exudate   →   mononuclear infiltrate in endometrial stroma   Endometrium: endometritis acute - histology    Endometrium: endometritis chronic - histology    →   some cases develop mucoid to mucopurulent vulval discharge.
  • Metritis resolves spontaneously in a few weeks, with complete resolution of endometrial damage.
  • No lasting impairment of fertility.
  • May infect placenta, but rarely associated with abortion   Abortion: overview  .
  • Congenital infection has been reported.

Other Host Effects

  • Carried asymptomatically in stallions and many recovered mares.


Control via animal

Clinical cases
  • Intra-uterine infusion of disinfectant or antimicrobials.
  • Topical treatment.
  • Systemic antibiotics.


  • Imported stallions: cleansing and antibacterials applied to external genitalia.
  • Mate imported stallions to uninfected mares, then culture mares forT. equigenitalisand test serologically for development of antibodies to the bacterium .
  • Culture from uterus or cervix, clitoral fossa and clitoral sinuses of imported mares repeatedly during one estrus cycle.
  • Surgical obliteration of the clitoral sinuses to eliminate carriage in mares   Clitoris: surgery  .

Control via chemotherapies

Control via environment

  • Not indicated.


  • None currently available.

Other countermeasures

  • Hygiene during breeding is important.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Moore et al (2001) Molecular surveillance of the incidence of Taylorella equigenitalis and Psedomonas aeruginosa from horses in Ireland by sequence-specific PCR. Equine Vet J 33 (3), 319-322 PubMed.
  • Katz J B, Evans L E et al (2000) Clinical, bacteriologic, serologic and pathologic features of infections with atypical Taylorella equigenitalis in mares. JAVMA 216 (12), 1945-1948 PubMed.
  • Timoney P J (1996) Contagious equine metritis. Comp Immunol Microbiol Infect Dis 19 (3), 199-204 PubMed.

Other sources of information

  • Horserace Betting Levy Board (2016) Codes of Practice. 5th Floor, 21 Bloomsbury Street, London WC1B 3HF, UK. Tel: +44 (0)207 333 0043; Fax: +44 (0)207 333 0041; Email: enquiries@hblb.org.uk; Website: http://codes.hblb.org.uk.