Equis ISSN 2398-2977

Reproduction: breeding assessment examination - mare

Synonym(s): Breeding fitness examination, Breeding soundness examination

Contributor(s): Allan Gunn, Madeleine L H Campbell

Introduction

  • Horses are classically described as being ‘long day seasonal breeders’. Most mares are acyclical, ie the reproductive tract is inactive, during short days (the winter, non-breeding season), and cycle regularly during long days (the summer, breeding season).
  • In between periods of cyclicity and acyclicity (in spring and autumn), mares experience two ‘transitional’ periods, during which they may cycle erratically.
  • The timing of assessment of fertility depends upon the reason for carrying out the examination.

Uses

  • Assessment of the likelihood of a mare becoming pregnant to a fertile stallion (including natural mating, fresh, chilled, and frozen semen) inseminated at an appropriate time in the estrous cycle; AND maintaining the pregnancy to term resulting in a viable foal. In this scenario, the examination would most usually be carried out during the breeding (long days) season.
  • Assessment of a mare who has failed to conceive as a result of covering or insemination:
    • These examinations may be carried out during the breeding season, at the end of the breeding season, or during the non-breeding (short days) season.
    • Carrying out a breeding soundness examination at the end of the breeding season or during the non-breeding season has the advantage that there is a prolonged period of sexual rest and acyclicity, in which mares can be treated (particularly useful for intrauterine treatments).
    • The disadvantage is that it is impossible to assess during the non-breeding season whether the mare cycles regularly during the breeding season.

Advantages

  • Assessing the suitability of a mare for reproductive purposes: a maiden mare, a mare for sale.
  • Diagnosis of the reasons for a mare not being pregnant, despite appropriate breeding management, to facilitate treatment.

Disadvantages

  • The process can be time consuming and expensive.
  • The predictability suggests a likelihood of suitability as a broodmare, or of a mare becoming pregnant following treatment, rather than being definitive.

Requirements

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Preparation

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Procedure

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Aftercare

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Outcomes

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Prognosis

  • Depends on the findings.

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Gunn A J, Chopin J B & Norman S T (2012) Examination of the mare for reproductive purposes. Aust Equine Vet 31 (4), 37-42 SciQuest.
  • Snider T A, Sepoy C & Holyoak G R (2011) Equine endometrial biopsy reviewed: Observation, interpretation, and application of histopathologic data. Theriogenology 75 (9), 1567-1581 PubMed.
  • Kenney R M (1978) Cyclic and pathologic changes of the mare endometrium as detected by biopsy, with a note on early embryonic death. JAVMA 172 (3), 241-262 PubMed.

Other sources of information

  • Brinsko S et al (2011) Breeding Soundness of the Mare. In: Manual of Equine Reproduction. Eds: Brinsko S et al. 3rd edn. Elsevier. pp 30-53.
  • Bowman T R J (2011) Direct Rectal Palpation. In: Equine Reproduction. Eds: McKinnon A O, Squires E L, Vaala W E & Varner D D. Wiley, UK. pp 1904-1913.
  • Card C E (2011) Endoscopic Examination. In:  Equine Reproduction. Eds: McKinnon A O, Squires E L, Vaala W E & Varner D D. Wiley, UK. pp 1940-1950.
  • Lear T L & Villagomez D A F (2011) Cytogenetic Evaluation of Mares and Foals. In: Equine Reproduction. Eds: McKinnon A O, Squires E L, Vaala W E & Varner D D. Wiley, UK. pp 1951-1962.
  • LeBlanc M M (2011) Uterine Cytology. In: Equine Reproduction. Eds: McKinnon A O, Squires E L, Vaala W E & Varner D D. Wiley, UK. pp 1922-1928.
  • Love C C (2011) Endometrial Biopsy. In: Equine Reproduction. Eds: McKinnon A O, Squires E L, Vaala W E & Varner D D. Wiley, UK. pp 1929-1939.
  • Pycock J F (2011) Ultrasonography. In: Equine Reproduction. Eds: McKinnon A O, Squires E L, Vaala W E & Varner D D. Wiley, UK. pp 1914-1921.
  • Ricketts S W (2011) Uterine and Clitoral Cultures. In: Equine Reproduction. Eds: McKinnon A O, Squires E L, Vaala W E & Varner D D. Wiley, UK. pp 1963-1978.
  • Zent W W (2011) History. In: Equine Reproduction. Eds: McKinnon A O, Squires E L, Vaala W E & Varner D D. Wiley, UK. pp 1897-1899.
  • Zent W W & Steiner J V (2011) Vaginal Examination. In: Equine Reproduction. Eds: McKinnon A O, Squires E L, Vaala W E & Varner D D. Wiley, UK. pp 1900-1903.
  • Kannegieter N & Major D A (2004) Guide to Examination of Horses. Equine Vet Aus pp 124-127.
  • Pycock J (1998) Evaluation of the Reproductive System in Stallions and Mares for Breeding Purposes. In: British Equine Veterinary Association Manual. Eds: Mair T. BEVA, UK. pp 138-147.

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