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The Canadian veterinary journal = La revue veterinaire canadienne2019; 60(8); 855-858;

Deslorelin and naltrexone stimulate follicular development in mares during autumn transition and early anestrus.

Abstract: Horses are long-day breeders and commence ovarian follicular activity during the spring. Evidence suggests that there is an endogenous circannual rhythm in mares, and it is uncertain whether hormonal manipulation during or immediately following the fall transition induces follicular development. The current study was designed to test the hypothesis that both deslorelin and naltrexone induce follicular development in late fall transitioning or anestrous mares. Five of six mares treated with deslorelin, and 4 of 6 mares treated with naltrexone, developed a pre-ovulatory-sized follicle and were inseminated. Zero of three deslorelin-control mares and 1 of 3 naltrexone-control mares were inseminated. The number of mares bred in the deslorelin treatment group was significantly higher than in the corresponding control group ( < 0.05). Six of nine mares inseminated were pregnant 14 days after insemination. In conclusion, we were able to induce follicular development resulting in fertile ovulations during and shortly after the fall transition. . Les chevaux sont des reproducteurs saisonniers influencés par la lumière du jour et l’activité folliculaire ovarienne débute au printemps. Les évidences suggèrent que chez les juments il y a un rythme circannuel endogène, et il est incertain si une manipulation hormonale durant ou immédiatement après la transition automnale induit le développement folliculaire. La présente étude a été conçue afin de vérifier l’hypothèse que le deslorelin et le naltrexone induisent le développement folliculaire tard à l’automne lors de la période de transition ou chez des juments en anoestrus. Cinq des six juments traitées avec du deslorin et quatre des six juments traitées avec du naltrexone ont développé un follicule de taille pré-ovulatoire et ont été inséminées. Aucune des trois juments témoins pour le deslorin et une des trois juments témoins pour le naltrexone furent inséminées. Le nombre de juments saillies dans le groupe de traitement deslorin était significativement supérieur à celui du groupe témoin correspondant (P < 0,05). Six des neuf juments inséminées étaient gestantes 14 jours après l’insémination. En conclusion, nous avons été en mesure d’induire le développement folliculaire résultant en des ovulations fertiles durant et tôt après la transition automnale.(Traduit par D Serge Messier).
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Publication Date: 2019-08-09 PubMed ID: 31391602PubMed Central: PMC6625173
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  • Journal Article

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 article suggests that hormonal treatments with deslorelin and naltrexone can effectively stimulate ovarian follicular development in mares during late fall, leading to successful inseminations.

Objective of the Study

The objective of this study was to evaluate the effects of hormonal treatments – specifically with deslorelin and naltrexone – on ovarian follicular development in mares during late fall transition and early anestrus stages. The hypothesis was that these treatments would induce development in mares, thereby leading to successful inseminations.

Methods and Treatment Groups

  • The study involved several groups of mares which were treated with either deslorelin or naltrexone.
  • Controls for both treatments were also maintained.
  • The treatments were administered during late fall transition and early anestrus stages.
  • The test subjects were monitored for appearance of pre-ovulatory-sized follicles, which was followed by insemination.

Findings of the Study

The study found that the treatments had a significant impact on follicular development in mares:

  • Five out of six mares treated with deslorelin developed a pre-ovulatory-sized follicle and were inseminated.
  • Four out of six mares in the naltrexone group showed similar results.
  • None of the deslorelin-control mares and only one of the naltrexone-control mares developed a pre-ovulatory-sized follicle and were inseminated.
  • The number of mares bred in the deslorelin treatment group was significantly higher than in the corresponding control group.

Conclusion of the Study

The hormonal treatments – deslorelin and naltrexone – were found to effectively induce follicular development in mares during the fall transition and early anestrus stages. Not only did this result in successful inseminations, but it also led to pregnancies, as 6 out of the 9 inseminated mares were found to be pregnant 14 days after insemination. These findings suggest that it could be possible to manipulate the breeding season of mares through the use of these hormonal treatments.

Cite This Article

APA
Kwong GPS, Klein C. (2019). Deslorelin and naltrexone stimulate follicular development in mares during autumn transition and early anestrus. Can Vet J, 60(8), 855-858.

Publication

The Canadian veterinary journal = La revue veterinaire canadienne
ISSN: 0008-5286
NlmUniqueID: 0004653
Country: Canada
Language: English
Volume: 60
Issue: 8
Pages: 855-858

Researcher Affiliations

Kwong, Grace P S
  • Faculty of Veterinary Medicine, University of Calgary, 3280 Hospital Drive NW, Calgary, Alberta T2N 4Z6.
Klein, Claudia
  • Faculty of Veterinary Medicine, University of Calgary, 3280 Hospital Drive NW, Calgary, Alberta T2N 4Z6.

MeSH Terms

  • Anestrus
  • Animals
  • Female
  • Horses
  • Naltrexone
  • Ovulation
  • Pregnancy
  • Triptorelin Pamoate / analogs & derivatives

References

This article includes 26 references
  1. Hughes JP, Stabenfeldt GH, Evans JW. The oestrous cycle of the mare.. J Reprod Fertil Suppl 1975 Oct;(23):161-6.
    pubmed: 1060771
  2. Goldman BD. Mammalian photoperiodic system: formal properties and neuroendocrine mechanisms of photoperiodic time measurement.. J Biol Rhythms 2001 Aug;16(4):283-301.
    pubmed: 11506375doi: 10.1177/074873001129001980google scholar: lookup
  3. Hart PJ, Squires EL, Imel KJ, Nett TM. Seasonal variation in hypothalamic content of gonadotropin-releasing hormone (GnRH), pituitary receptors for GnRH, and pituitary content of luteinizing hormone and follicle-stimulating hormone in the mare.. Biol Reprod 1984 Jun;30(5):1055-62.
    pubmed: 6329338doi: 10.1095/biolreprod30.5.1055google scholar: lookup
  4. Collins SM, Zieba DA, Williams GL. Continuous administration of low-dose GnRH in mares II. Pituitary and ovarian responses to uninterrupted treatment beginning near the autumnal equinox and continuing throughout the anovulatory season.. Theriogenology 2007 Sep 1;68(4):673-81.
    pubmed: 17590426doi: 10.1016/j.theriogenology.2007.05.057google scholar: lookup
  5. Burkhardt J. Transition from anoestrus in the mare and the effect of artificial lighting. J Agric Sci 1947;37:64–68.
  6. Kooistra LH, Ginther OJ. Effect of photoperiod on reproductive activity and hair in mares.. Am J Vet Res 1975 Oct;36(10):1413-9.
    pubmed: 1238038
  7. Behrens C, Aurich JE, Klug E, Naumann H, Hoppen HO. Inhibition of gonadotrophin release in mares during the luteal phase of the oestrous cycle by endogenous opioids.. J Reprod Fertil 1993 Jul;98(2):509-14.
    pubmed: 8410818doi: 10.1530/jrf.0.0980509google scholar: lookup
  8. Davison LA, McManus CJ, Fitzgerald BP. Gonadotropin response to naloxone in the mare: effect of time of year and reproductive status.. Biol Reprod 1998 Nov;59(5):1195-9.
    pubmed: 9780327doi: 10.1095/biolreprod59.5.1195google scholar: lookup
  9. Aurich C, Parvizi N, Brunklaus D, Hoppen HO, Aurich JE. Opioidergic and dopaminergic effects on LH and prolactin release in pony mares at different times of the year.. J Reprod Fertil Suppl 2000;(56):195-203.
    pubmed: 20681131
  10. Aurich C, Schlote S, Hoppen HO, Klug E, Hoppe H, Aurich JE. Effects of the opioid antagonist naloxone on release of luteinizing hormone in mares during the anovulatory season.. J Endocrinol 1994 Jul;142(1):139-44.
    pubmed: 7964272doi: 10.1677/joe.0.1420139google scholar: lookup
  11. Irvine CHG, Alexander SL, Turner JE. Differential effects of graded doses of naloxone on the reproductive and adrenal axes in seasonally anestrous mares. Endocrine 1994;2:913–919.
  12. Thorson JF, Prezotto LD, Cardoso RC, Allen CC, Alves BR, Amstalden M, Williams GL. Pharmacologic application of native GnRH in the winter anovulatory mare, II: accelerating the timing of pregnancy.. Theriogenology 2014 Mar 1;81(4):625-31.
    pubmed: 24388674doi: 10.1016/j.theriogenology.2013.11.017google scholar: lookup
  13. Turner JE, Irvine CH. The effect of various gonadotrophin-releasing hormone regimens on gonadotrophins, follicular growth and ovulation in deeply anoestrous mares.. J Reprod Fertil Suppl 1991;44:213-25.
    pubmed: 1839039
  14. Nickerson KC, McCue PM, Squires EL, Nett TM. Comparison of two dosage regimens of the GNRH agonist deslorelin acetate on inducing ovulation in seasonally anestrous mares. J Equine Vet Sci 1998;18:121–124.
  15. McCue PM. Management of seasonal anestrus: Hormone therapy. In: Dascanio J, McCue P, editors. Equine Reproductive Procedures. Ames, Iowa: John Wiley & Sons; 2014. pp. 146–148.
  16. Okamura H, Yamamura T, Wakabayashi Y. Kisspeptin as a master player in the central control of reproduction in mammals: an overview of kisspeptin research in domestic animals.. Anim Sci J 2013 May;84(5):369-381.
    pubmed: 23607315doi: 10.1111/asj.12056google scholar: lookup
  17. Decourt C, Caraty A, Briant C, Guillaume D, Lomet D, Chesneau D, Lardic L, Duchamp G, Reigner F, Monget P, Dufourny L, Beltramo M, Dardente H. Acute injection and chronic perfusion of kisspeptin elicit gonadotropins release but fail to trigger ovulation in the mare.. Biol Reprod 2014 Feb;90(2):36.
    pubmed: 24429215doi: 10.1095/biolreprod.113.114157google scholar: lookup
  18. Grubaugh W, Sharp DC, Berglund LA, McDowell KJ, Kilmer DM, Peck LS, Seamans KW. Effects of pinealectomy in Pony mares.. J Reprod Fertil Suppl 1982;32:293-5.
    pubmed: 6962863
  19. Sharp DC, Vernon MW, Zavy MT. Alteration of seasonal reproductive patterns in mares following superior cervical ganglionectomy.. J Reprod Fertil Suppl 1979;(27):87-93.
    pubmed: 289844
  20. Palmer E, Driancourt MA, Ortavant R. Photoperiodic stimulation of the mare during winter anoestrus.. J Reprod Fertil Suppl 1982;32:275-82.
    pubmed: 6820061
  21. Thompson DL Jr, Reville SI, Walker MP, Derrick DJ, Papkoff H. Testosterone administration to mares during estrus: duration of estrus and diestrus and concentrations of LH and FSH in plasma.. J Anim Sci 1983 Apr;56(4):911-8.
    pubmed: 6406417doi: 10.2527/jas1983.564911xgoogle scholar: lookup
  22. Ghasemi F, Manning ST, Rauch A, Chavarria NKH, Card CE. Ovarian response to injectable deslorelin during anestrus in mares. Proceedings of the American Association of Equine Practitioners (AAEP) Baltimore, Maryland. 2010; pp. 315–316.
  23. Dowling J, Isbister GK, Kirkpatrick CM, Naidoo D, Graudins A. Population pharmacokinetics of intravenous, intramuscular, and intranasal naloxone in human volunteers.. Ther Drug Monit 2008 Aug;30(4):490-6.
    pubmed: 18641540doi: 10.1097/ftd.0b013e3181816214google scholar: lookup
  24. Meyers-Brown GA, Loud MC, Hyland JC, Roser JF. Deep anestrous mares under natural photoperiod treated with recombinant equine FSH (reFSH) and LH (reLH) have fertile ovulations and become pregnant.. Theriogenology 2017 Aug;98:108-115.
    pubmed: 28601147doi: 10.1016/j.theriogenology.2017.05.001google scholar: lookup
  25. Meyers-Brown GA, McCue PM, Troedsson MH, Klein C, Zent W, Ferris RA, Lindholm AR, Scofield DB, Claes AN, Morganti M, Colgin MA, Wetzel RL, Peters AR, Roser JF. Induction of ovulation in seasonally anestrous mares under ambient lights using recombinant equine FSH (reFSH).. Theriogenology 2013 Sep 15;80(5):456-62.
    pubmed: 23768752doi: 10.1016/j.theriogenology.2013.04.029google scholar: lookup
  26. Ginther OJ. Reproductive Biology of the Mare: Basic and Applied Aspects. Cross Plains, Wisconsin: Equiservices; 1992. p. 140.

Citations

This article has been cited 1 times.
  1. Bukhari SSUH, Urooj S. Retinol and cholecalciferol affect buserelin-induced estrous in anestrous mares. Trop Anim Health Prod 2025 Mar 17;57(3):124.
    doi: 10.1007/s11250-025-04369-9pubmed: 40095200google scholar: lookup
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