Equine Ovulation Failure - Veterinary Research PDF

ovulation-inducing agent earlier in estrus to 'take control' before the follicle is committed to atresia. Unfortunately, none of these schemes are uniformly effective in preventing ovulation failure. If a mare does develop a luteinized anovulatory follicle, administration of a single dose of prostag...

ovulation-inducing agent earlier in estrus to 'take control' before the follicle is committed to atresia. Unfortunately, none of these schemes are uniformly effective in preventing ovulation failure. If a mare does develop a luteinized anovulatory follicle, administration of a single dose of prostaglandin (e.g., 250 µg cloprostenol sodium) 9 days after initial observation of echogenic particles or strands within the follicular lumen will result in the destruction of the luteal cells, a rapid decline in serum progesterone levels (Figure 279.6), and a return to estrus. Prostaglandin treatment has no apparent effect on non-luteinized anovulatory follicles. Fortunately, a majority of non-luteinized anovulatory follicles will spontaneously regress in 1--4 weeks. Administration of hCG or the GnRH agonist deslorelin has not been effective in inducing ovulation or luteinization of this type of anovulatory follicle. Aspiration of a persistent anovulatory follicle using a transvaginal ultrasound-guided approach has been described.32 We have also attempted to eliminate a non-luteinized anovulatory follicle by transvaginal follicular aspiration. In our case, a majority of follicular fluid was successfully removed, but the collapsed follicular structure remained present for more than 2 weeks. Aspiration did not result in an early regression or luteinization of the follicle and suggested that the structure was non-viable or atretic. Alternative management option Mares that repeatedly form anovulatory follicles during estrus are a major source of frustration for owners, breeding managers, and veterinarians. One option for 'repeat offenders' is referral to an assisted reproduction program offering oocyte collection.33 The dominant follicle may be aspirated and the oocyte recovered before the follicle becomes hemorrhagic or atretic. The oocyte may be surgically transferred into the oviduct of a recipient mare that has been inseminated (i.e., oocyte transfer), transferred into the oviduct of a recipient mare along with spermatozoa (i.e., gamete intrafallopian transfer), or injected with a single spermatozoon and the developing embryo transferred into a recipient mare (i.e., intracytoplasmic sperm injection). In one report, ovulation failure was the most common reason cited for mares entering into an assisted reproduction program.34 References 1. McKinnon AO. Ovarian abnormalities. In: Rantanen NW, McKinnon AO (eds) Equine Diagnostic Ultrasonography. Baltimore: Williams & Wilkins, 1997. 2. Pierson RA. Folliculogenesis and ovulation. In: McKinnon AO, Voss JL (eds) Equine Reproduction. Philadelphia: Lea & Febiger, 1993. 3. Ginther OJ, Gastal EL, Gastal MO, Beg MA. Conversion of a viable preovulatory follicle into a hemorrhagic anovulatory follicle in mares. Anim Reprod 2006;3:29--40. 4. Ginther OJ, Gastal EL, Gastal MO, Beg MA. Incidence, endocrinology, vascularity, and morphology of hemorrhagic anovulatory follicles in mares. J Equine Vet Sci 2007;27:130--9. 5. McCue PM, Squires EL. Persistent anovulatory follicles in the mare. Theriogenology 2002;58:541. 6. Allen WR, Kolling M, Wilsher S. An interesting case of early ¨ pregnancy loss in a mare with persistent endometrial cups. Equine Vet Educ 2007;19:539--44. 7. Willis LA, Riddle WT. Theriogenology question of the month. J Am Vet Med Assoc 2005;226:877--9. 8. Steiner J, Antzak DF, Wolfsdorf K, Saville K, Brooks S, Miller D, Bailey E, Zent W. Persistent endometrial cups. Anim Reprod Sci 2006;94:274--5. 9. Hedberg Y, Dalin A-M, Forsberg M, Lundeheim N, Hoffmann B, Ludwig C, Kindahl H. Effect of ACTH (tetracosactide) on steroid hormone levels in the mare. Part A: effect in intact normal mares and mares with possible estrus-related behavioral abnormalities. Anim Reprod Sci 2007;100:73--91. 10. Hedberg Y, Dalin A-M, Forsberg M, Lundeheim N, Sandh G, Hoffmann B, Ludwig C, Kindahl H. Effect of ACTH (tetracosactide) on steroid hormone levels in the mare. Part B: effect in ovariectomized mares (including estrous behavior). Anim Reprod Sci 2007;100:92--106. 11. Asa CS, Ginther OJ. Glucocorticoid suppression of oestrus, follicles, LH and ovulation in the mare. J Reprod Fertil Suppl 1982;32:247--51. 12. Ferris RA, McCue PM. The effects of dexamethasone and prednisolone on pituitary and ovarian function in the mare. Clin Theriogenol 2009;1:225. 13. Macfarlane MS, Breen KM, Sakurai H, Adams BM, Adams TE. Effect of duration of infusion of stress-like concentrations of cortisol on follicular development and the preovulatory surge of LH in sheep. Anim Reprod Sci 2000;63: 167--75. 14. Scholten JA, Liptrap RM. A role for the adrenal cortex in the onset of cystic ovarian follicles in the sow. Can J Comp Med 1978;42:525--33. 15. McKinnon AO, Perriam WJ, Lescun TB, Walker J, Vasey JR, Trigg TE. Effect of a GnRH analogue (Ovuplant), hCG and dexamethasone on time to ovulation in cycling mares. World Equine Vet Rev 1997;2:16--18. 16. Lefranc A-C, Allen WR. Incidence and morphology of anovulatory haemorrhagic follicles in the mare. Pferdeheilkunde 2003;19:611--12. 17. Gastal EL, Gastal MO, Ginther OJ. The suitability of echotexture characteristics of the follicular wall for identifying the optimal breeding day in mares. Theriogenology 1998;50:1025--38. 18. Stangroom JE, Weevers RG. Anticoagulant activity of equine follicular fluid. J Reprod Fertil 1962;3:269--82. 19. Blanchard TL, Varner DD, Schumacher J, Love CC, Brinsko SP, Rigby SL. Manual of Equine Reproduction, 2nd edn. St Louis, MO: Mosby, 2003. 20. Sullivan JJ, Parker WG, Larson LL. Duration of estrus and ovulation time in nonlactating mares given human chorionic gonadotropin during three successive estrous periods. J Am Vet Med Assoc 1973;162:895. P1: SFK/UKS P2: SFK Color: 1C c279 BLBK232-McKinnon February 2, 2011 15:57 Trim: 279mm X 216mm Printer Name: Yet to Come Disorders of Ovulation 2691 21. Duchamp G, Bour B, Combarnous Y, Palmer E. Alternative solutions to hCG induction of ovulation in the mare. J Reprod Fertil Suppl 1987;35:221. 22. McCue PM, Hudson JJ, Bruemmer JE, Squires EL. Efficacy of hCG at inducing ovulation: a new look at an old issue. Proceedings of the 50th Annual Meeting of the American Association of Equine Practitioners, 2004; pp. 510--13. 23. Barbacini S, Zavaglia G, Gulden P, Marchi V, Necchi D. Retrospective study on the efficacy of hCG in an equine artificial insemination programme using frozen semen. Equine Vet Educ 2000;12:404. 24. Farquhar VJ, McCue PM, Vanderwall DK, Squires EL. Efficacy of the GnRH agonist deslorelin acetate for inducing ovulation in mares relative to age of mare and season. J Equine Vet Sci 2000;20:722--5. 25. Bruemmer JE, Coy RC, Olson A, Squires EL. Efficacy of altrenogest administration to postpone ovulation and subsequent fertility in mares. J Equine Vet Sci 2000;20:450--3. 26. Denniston DJ, Crabb JJ, Bruemmer JE, Squires EL. Effects of a gonadotropin-releasing hormone antagonist and altrenogest on luteinizing hormone concentration and ovulation in the mare. J Equine Vet Sci 2006;26:95--101. 27. Dell'Aqua JA Jr, Papa FO, Lopes MD, Alvarenga MA, Macedo LP, Melo CM. Modulation of acute uterine inflammatory response after artificial insemination with equine frozen semen. Anim Reprod Sci 2006;94:270--3. 28. Squires EL, McCue PM. Superovulation in mares. Anim Reprod Sci 2007;99:1--8. 29. Niswender KD, Alvarenga MA, McCue PM, Hardy QP, Squires EL. Superovulation in cycling mares using equine follicle stimulating hormone (eFSH). J Equine Vet Sci 2003;23:497--500. 30. Logan NL, McCue PM, Alonso MA, Squires EL. Evaluation of three equine FSH superovulation protocols in mares. Anim Reprod Sci 2007;102:48--55. 31. McCue PM. Equine Cushing's disease. Vet Clin Equine 2002;18:533--43. 32. Bruck I, Larsen SB, Greve T. Transvaginal ultraly- ¨ dovervaget aspiration af en anovulatorisk follikel hos en ˚ hoppe. Dansk Veterinærtidsskrift 1995;78:717--20. 33. Coutinho da Silva MA. When should a mare go for assisted reproduction? Theriogenology 2008;70:441--4. 34. Carnevale EM, Alvarenga MA, Squires EL. Use of oocyte transfer in a commerc