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Home / Equine Research Bank / Vet J / Preovulatory progestagen treatment in mares fails to delay o...
Veterinary journal (London, England : 1997)2013; 197(2); 324-328; doi: 10.1016/j.tvjl.2012.12.028

Preovulatory progestagen treatment in mares fails to delay ovulation.

Abstract: The major objective of this study was to determine whether short-term preovulatory progestagen treatment of mares could effectively delay ovulation. Secondary objectives were to determine the effect such supplementation had on signs of estrus, follicular growth, postovulatory luteal function and pregnancy rate. Thirteen cyclic mares of different breeds were used in this study during the natural breeding season. Once mares were confirmed in estrus with a follicle of 35 mm in diameter, they were assigned in random order to receive no treatment (control), placement of a progesterone-impregnated controlled intravaginal drug releasing device (CIDR) for 2 days, or oral altrenogest treatment (0.044 mg/kg/d) for 2 days. Transrectal ultrasonography and teasing with a vigorous stallion were performed daily. Mares were inseminated every 48 h after the end of experimental treatment (progestagen groups) or beginning when the follicular diameter was 35 mm (control group) with fresh extended semen of a single fertile stallion. Each mare was followed for 3-5 cycles, allowing each treatment to be applied one or two times. Neither CIDR nor altrenogest treatment delayed ovulation. Treatment had no effect on follicular growth rate or the size of the ovulatory follicle immediately preceding ovulation. Both forms of progestagen treatment effectively abolished estrous behavior within 24h. Estrous response to the stallion returned to the control level after cessation of treatment. Similarly, a reduction in endometrial edema was detected during progestagen treatment, which returned to normal after cessation of treatment. Altrenogest treatment tended to reduce the chance of pregnancy (P=0.09) compared to the control group. The use of progestagens to delay ovulation in mares lacks efficacy and may threaten successful establishment of pregnancy.
Copyright © 2013 Elsevier Ltd. All rights reserved.
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Publication Date: 2013-02-04 PubMed ID: 23384437DOI: 10.1016/j.tvjl.2012.12.028Google Scholar: Lookup
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  • Journal Article
  • Randomized Controlled Trial
  • Research Support
  • Non-U.S. Gov't

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research paper investigates whether a short-term preovulatory progestagen treatment could potentially delay ovulation in mares. The study concludes that the treatment does not delay ovulation nor influence follicular growth, but it does affect estrous behavior and potentially decreases the chances of pregnancy.

Objective and Methodology

  • The main objective of this study was to investigate the effects of a short-term preovulatory progestagen treatment on mares. The researchers sought to determine if the treatment could effectively delay ovulation.
  • The study analyzed secondary factors such as the effects of the treatment on estrus signs, follicular growth, postovulatory luteal function, and pregnancy rate.
  • The study sample consisted of thirteen cyclic mares of different breeds. The experiment was performed during the natural breeding season.
  • The mares were divided into control and treatment groups. The treatment groups were either given a progesterone-impregnated controlled intravaginal drug releasing device or an oral altrenogest treatment for two days.
  • The mares were monitored daily via transrectal ultrasonography and teasing with a stallion.

Results of the Study

  • The primary finding of the study was that neither of the progestagen treatments delayed ovulation in the mares.
  • The treatments also did not have an impact on follicular growth rate or the size of the ovulatory follicle before ovulation.
  • The treatments did, however, effectively abolish estrous behavior within 24 hours. This response returned to control level following the cessation of treatment.
  • The treatments also caused a reduction in endometrial edema, which also returned to normal following the cessation of the treatment.
  • The altrenogest treatment seemed to decrease the chances of pregnancy compared to the control group, though this finding was not statistically significant (P=0.09).

Conclusion of the Study

  • The study concluded that using progestagens to delay ovulation in mares is not effective.
  • Moreover, the results suggest that progestagen use may actually pose a risk to the successful establishment of the mare’s pregnancy.

Cite This Article

APA
Canisso IF, Gallacher K, Gilbert MA, Korn A, Schweizer CM, Bedford-Guaus SJ, Gilbert RO. (2013). Preovulatory progestagen treatment in mares fails to delay ovulation. Vet J, 197(2), 324-328. https://doi.org/10.1016/j.tvjl.2012.12.028

Publication

Veterinary journal (London, England : 1997)
ISSN: 1532-2971
NlmUniqueID: 9706281
Country: England
Language: English
Volume: 197
Issue: 2
Pages: 324-328
PII: S1090-0233(13)00010-5

Researcher Affiliations

Canisso, Igor F
  • Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853-6401, USA.
Gallacher, Kirsten
    Gilbert, Mary-Anne
      Korn, Alexandra
        Schweizer, Christine M
          Bedford-Guaus, Sylvia J
            Gilbert, Robert O

              MeSH Terms

              • Animals
              • Delayed-Action Preparations
              • Drug Administration Schedule
              • Estrus Synchronization
              • Female
              • Horses / physiology
              • Ovulation / drug effects
              • Ovulation / physiology
              • Pregnancy
              • Progesterone / administration & dosage
              • Progesterone / pharmacology
              • Progestins / administration & dosage
              • Progestins / pharmacology
              • Trenbolone Acetate / administration & dosage
              • Trenbolone Acetate / analogs & derivatives
              • Trenbolone Acetate / pharmacology

              Citations

              This article has been cited 3 times.
              1. Segabinazzi LGTM, Roberts BN, Peterson EW, Ambrosia R, Bergfelt D, Samper J, French H, Gilbert RO. Early Pregnancy in Jennies in the Caribbean: Corpus Luteum Development and Progesterone Production, Uterine and Embryo Dynamics, Conceptus Growth and Maturation.. Animals (Basel) 2022 Jan 6;12(2).
                doi: 10.3390/ani12020127pubmed: 35049751google scholar: lookup
              2. Segabinazzi LGTM, Andrade LRP Jr, Alvarenga MA, Dell'Aqua JA Jr, Canisso IF. Use of Intravaginal Progesterone-Releasing Device Results in Similar Pregnancy Rates and Losses to Long-Acting Progesterone to Synchronize Acyclic Embryo Recipient Mares.. Vet Sci 2021 Sep 10;8(9).
                doi: 10.3390/vetsci8090190pubmed: 34564584google scholar: lookup
              3. Segabinazzi LGTM, Canisso IF, Podico G, Cunha LL, Novello G, Rosser MF, Loux SC, Lima FS, Alvarenga MA. Intrauterine Blood Plasma Platelet-Therapy Mitigates Persistent Breeding-Induced Endometritis, Reduces Uterine Infections, and Improves Embryo Recovery in Mares.. Antibiotics (Basel) 2021 Apr 23;10(5).
                doi: 10.3390/antibiotics10050490pubmed: 33922743google scholar: lookup
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