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Semen: urosemen

ISSN 2398-2977

Synonym(s): Urospermia, urine in the semen


  • Urine in the semen.
  • Cause: not well understood.
  • Signs: no generalized signs.
  • Diagnosis: semen evaluation.
  • Treatment: diuretic medication
  • Prognosis: good.

Presenting signs

  • Yellow coloration of ejaculate   Semen: urosemen  .
  • Unpleasant odor of ejaculate (ammonia).
  • Poor sperm motility.
  • Poor fertility.
  • When natural cover is being used poor fertility/high rates of post-breeding endometritis   Uterus: endometritis - bacterial  in the mares which have been covered may be the only clues.

Cost considerations

  • Repeated attempts at semen collection and/or inability to use certain ejaculates can become expensive due to time and personnel involved.
  • Mares inseminated/covered with urine-contaminated semen may develop a (chemical) endometritis   Uterus: endometritis - bacterial  , and thus incur additional costs.



  • Not well understood.
  • The sphincter at the neck of the bladder which ought to close tightly during ejaculation fails to do so sufficiently, and so urine leaks down the urethra (the common pathway for semen and urine) and contaminates the ejaculate:

Predisposing factors



  • Some stallions contaminate every ejaculate with urine.
  • In other stallions the problem is intermittent.


Presenting problems

  • Yellow coloration of ejaculate.
  • Unpleasant odor of ejaculate (ammonia).
  • Poor sperm motility.
  • Even small amounts of urine in ejaculate have detrimental effect on motility/fertility.

Client history

  • May report low pregnancy rate.
  • May report large number of mares with post-breeding endometritis    Endometrium: endometritis acute - histology  .
  • If using artificial insemination   Reproduction: artificial insemination  may have noticed abnormally large volume of ejaculate, abnormal color, abnormal smell.

Clinical signs

  • Normally no generalized clinical signs, unless suffering generalized concurrent neurological disease.

Diagnostic investigation

  • Semen evaluation   Semen: evaluation  :
    • Abnormally large volume.
    • Ammonia odor to ejaculate.
    • Abnormal (yellow) color of ejaculate.

If contamination minimal none of these may be evident.

Definitive diagnostic features

  • Laboratory analysis of ejaculate:
    • Calcium carbonate crystals on microscopic examination.
    • Urea nitrogen and creatinine concentrations.
    • Can use test strip.

Differential diagnosis

  • Other causes of poor semen motility, eg:
    • Iatrogenic.
    • Testicular degeneration.
    • Infection.
    • Hemospermia.


Standard treatment

  • Perform neurological examination   Neurology: examination - adult  .
  • Rule out urinary tract infection (causing bladder irritation).
  • Encourage stallion to urinate immediately before semen collection/covering.
    • Put in stable with new clean bed.
    • Put in paddock which other horses have been in.
    • ? diuretic medication, eg furosemide   Furosemide  .
  • Centrifuge ejaculate immediately after collection; remove urine-containing supernatant; resuspend to desired concentration in semen extender.
  • Can try using an open-ended artificial vagina and not collecting the urine-contaminated portion of the ejaculate.
  • Bethanecol chloride; impiramine and oxytocin   Oxytocin  have been reported as treatments for urospermia: none has produced consistent positive results.


  • Monitor gross appearance/smell, pH, calcium carbonate crystal content and urea nitrogen and creatinine concentrations of ejaculate.
  • Monitor number of mares with post-breeding endometritis   Endometrium: endometritis acute - histology  .

Subsequent management


  • Some stallions have persistent and consistent urospermia. 
  • In other stallions the condition is intermittent. 
  • Therefore best to assume it may happen with every ejaculation and manage accordingly.




  • Prognosis for fertility is good with appropriate, careful management.
  • Prognosis for resolution of the urospermia is poor.

Expected response to treatment

  • Normal ejaculate/ejaculate which is not contaminated post-centrifugation.

Reasons for treatment failure

  • Failure to identify the problem accurately.
  • Overriding neurological disease.

Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Loomis P R (2006) Advanced methods for handling and preparation of stallion semen. Vet Clin North Am Equine Pract 22 (3), 663-676 PubMed.
  • Griggers S, Paccamonti D L, Thompson R A & Eilts B E (2001) The effects of ph, osmolarity and urine contamination on equine spermatozoal motility. Theriogenology 56 (4), 613-622 PubMed.

Other sources of information

  • Turner R M O (2007) Urospermia and Hemospermia. In: Current Therapy in Equine Reproduction. Eds: Samper J, Pycock J F & McKinnon A O. pp 258-260.