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Effect of post-insemination dexamethasone treatment on pregnancy rates in mares
Animal Reproduction Science 121S (2010) S110–S112
Contents lists available at ScienceDirect
Animal Reproduction Science journal homepage: www.elsevier.com/locate/anireprosci
Abstract
Effect of post-insemination dexamethasone treatment on pregnancy rates in mares夽 H. Vandaele a,∗ , P. Daels a , S. Piepers b , M. LeBlanc c a b c
Keros AI and ET Center, Passendale, Belgium School of Veterinary Medicine, Ghent University, Ghent, Belgium Rood and Riddle Equine Hospital, Lexington, USA
1. Introduction Uterine inflammation is considered as a physiological response to the presence of semen in the uterus. In normal fertile mares, this inflammatory response ends approximately 36 h after mating but in susceptible mares the semen-induced inflammation lasts much longer. Persistent mating-induced endometritis may alter the uterine environment resulting in early embryonic loss. It has been suggested that modulation of this inflammatory response may improve fertility in susceptible mares. Bucca et al. (2008) examined the effect of dexamethasone in 347 mares over 513 estrous cycles and reported that a single dose of 50 mg dexamethasone given at the time of insemination did not have a deleterious effect on the pregnancy rate. They also observed a correlation between dexamethasone treatment and increased pregnancy rate in three subsets of mares: mares with three or more risk factors for endometritis, susceptible mares with more than 2 cm of uterine fluid after mating, and mares where intrauterine fluid persisted 36 h after mating. Others have reported increased pregnancy rates in subfertile mares with a history of post-insemination fluid accumulation when they are given prednisolone every 12 h beginning 24 h before mating and continuing until ovulation (Papa et al., 2008). As clinical signs of post-mating endometritis are not usually evident in mares until after insemination, and as the reproductive history is not always available, it is difficult
夽 This paper is part of the supplement entitled “Proceedings of the Tenth International Symposium on Equine Reproduction”, Guest Edited by Margaret J. Evans. ∗ Corresponding author. E-mail address: [email protected] (H. Vandaele). 0378-4320/$ – see front matter doi:10.1016/j.anireprosci.2010.04.074
to determine which mares should be treated with steroids before mating. Therefore, in clinical practice, steroids have been given after mating to mares with intrauterine fluid, but it is not known if this treatment improves pregnancy rates. The aim of this study was to determine if intravenous administration of dexamethasone after insemination increases pregnancy rates. 2. Materials and methods Client-owned mares (n = 774 cycles; 359 mares) presented for breeding at Keros AI and ET Center during the 2008 breeding season were assigned randomly to one of three treatment groups: T0 = no treatment (n = 327); T1 = 10 mg dexamethasone (Rapidexon® , Eurovet Animal Health, The Netherlands) given i.v. (n = 245); T2 = 20 mg dexamethasone (n = 202). The dexamethasone (Groups T1 and T2) was given 6–12 h after insemination. Each week one-treatment type was applied to all inseminated mares, except mares in competition. Treatments were repeated every 3 weeks between May 10 and August 31. Mares ranged in age from 2 to 28 years (mean age = 11 years). Mares were artificially inseminated either with cooled semen (n = 542 cycles) or frozen semen (n = 232 cycles). Mares received additional reproductive medical treatments after breeding as deemed necessary, including large volume uterine lavage, oxytocin, prostaglandin, intrauterine and/or systemic antibiotics and altrenogest. The amount of intrauterine fluid was noted before insemination and at 6–12 h after insemination. Pregnancy was diagnosed by ultrasonography at 14–17 days (US group; n = 419 cycles; 245 mares) or by embryo recovery on Day 7 or 8 after ovulation (ET group; n = 355 cycles; 114 mares). Data were analysed by logistic regression with pregnancy status as the binary dependent variable (0 = not pregnant;
H. Vandaele et al. / Animal Reproduction Science 121S (2010) S110–S112 Table 1 Pregnancy rates in mares treated 6–12 h after insemination with dexamethasone. DEX (mg)
US
ET flush
n
Preg
%
0 10 20
193 114 112
98 67 62
50.7 58.8 55.4
n 134 131 90
Table 3 Effect of age on pregnancy rate in mares treated with dexamethasone 6–12 h after breeding. DEX (mg)
Preg
%
61 57 41
45.5 43.5 45.5
US = ultrasound group, ET flush = mares for embryo flush, DEX = dose of dexamethasone given, n = number of mares, Preg = number of pregnant mares, % = pregnancy rate.
S111
US n
ET flush Preg
Less than 14 years of age 0 116 60 10 78 48 20 72 41 More than 14 years of age 0 77 38 10 36 19 20 40 21
%
n
Preg
%
51.7 61.5 56.9
89 86 66
44 40 31
49.4 46.5 47.0
49.3 52.7 52.5
46 45 23
17 17 9
37.0 37.7 39.1
Table 2 Pregnancy rates in mares with intrauterine fluid either before or after insemination treated with dexamethasone 6–12 h after insemination. DEX (mg)
US n
ET flush Preg
%
Intrauterine fluid before insemination 0 14 4 28.6 10 11 4 36.4 20 11 4 36.4 Intrauterine fluid after insemination 0 65 23 35.3 10 32 14 43.7 20 38 14 36.8
n
Preg
%
24 28 15
8 6 5
33.3 21.4 33.3
53 68 47
24 28 16
45.2 41.1 34.0
1 = pregnant), and treatment strategy, intrauterine fluid and mare age as categoric independent variables (SPSS16.0, SPSS Inc., Chicago, IL). All first-order interactions were tested and removed when non-significant statistical significance was assessed at P < 0.05. 3. Results Pregnancy rates per cycle were higher in the US group (54%, 227 pregnancies out of 419 cycles) than in the ET group (45%, 159 positive collections, one or more embryos, out of 355 cycles; P < 0.01). Therefore, the effect of dexamethasone was examined separately for the two groups. Dexamethasone treatment did not affect pregnancy rates in either group (Table 1). Also, dexamethasone treatment did not improve pregnancy rates in mares that had intrauterine fluid before or after insemination (Table 2). When considering all treated and non-treated mares combined, pregnancy rates were higher (P = 0.01) in mares that did not have intrauterine fluid before insemination (US group: n = 383 cycles; 56.1% and ET group: n = 288 cycles; 48.3%) than in mares with intrauterine fluid before insemination (US group: n = 36; 33.3% and ET group: n = 67; 28.4%; see Table 2). In addition, mares with fluid after insemination in the US group had lower pregnancy rates (n = 135; 37.8%; P = 0.001) than did US group mares without fluid after insemination (n = 284; 61.9%; Table 2). There was no effect of age on the efficacy of dexamethasone treatment (Table 3). 4. Discussion Unlike previous investigators, we did not observe an effect of dexamethasone on pregnancy rates when it was given after insemination either in the general population
of mares, in mares that had intrauterine fluid before or after breeding, or in aged mares. However, pregnancy rates were lower in mares with intrauterine fluid, regardless of treatment, than in mares without intrauterine fluid. Steroids block both the cyclo-oxygenase and 5-lipoxygenase pathways of inflammation. The 5lipoxygenase pathway includes leukotriene B, a potent neutrophil chemotactic factor found in uterine fluids of susceptible mares after mating (Watson et al., 1988). Reducing the neutrophil chemotaxis and the number of neutrophils recruited into the uterus post-mating may diminish the severity and length of the inflammatory response. Neutrophils migrate into the uterine lumen within minutes of insemination, peaking at 8–12 h postinsemination (Katila, 1995). Delaying dexamethasone administration until 6–12 h after insemination may not adequately inhibit or decrease neutrophil migration and the subsequent inflammatory response. Therefore it is possible that timing of treatment may have affected results. Bucca et al. (2008) and Papa et al. (2008) administered steroids before insemination while in this study dexamethasone was administered 6–12 h after insemination. In a clinical situation, it is often difficult to determine which mares should be treated with steroids before mating because many mares show no clinical signs of endometritis until later. Therefore a treatment that could be successfully implemented after insemination would have a considerable practical advantage. The dose of dexamethasone chosen in the present study (10 or 20 mg) is lower than in other studies because of concerns for adverse side effects such as laminitis. No adverse side effects were observed in the present study. Risk factors that may have adversely affected pregnancy rates in this study were restricted to age and the presence of fluid. The inclusion of more risk factors, as described by Bucca et al. (2008), might have identified a subset of mares in which dexamethasone treatment would have increased pregnancy rates in the present study. Clinical histories on many of the mares were either not precise or lacking and therefore were not included in the model. In conclusion, administration of 10 or 20 mg of dexamethasone 6–12 h after insemination did not improve pregnancy rates in mares bred with cooled or frozen semen, regardless of age or the presence of intrauterine fluid.
S112
H. Vandaele et al. / Animal Reproduction Science 121S (2010) S110–S112
Conflict of interest None. Acknowledgements The research was funded by the USDA-CSREES. The CpGODN used in this study was provided free of cost by Merial, Ltd. References Bucca, S., Carli, A., Buckley, T., Dolci, G., Fogerty, U., 2008. The use of dexamethasone administered to mares at breeding time in the modu-
lation of persistent mating induced endometritis. Theriogenology 70, 1093–1100. Katila, T., 1995. Onset and duration of uterine inflammatory response of mares after insemination with fresh semen. Biol. Reprod. Monogr. Ser. 1, 515–517. Papa, F.O., Alvarenga, J.A., Melo, M.A., Zahn, C.M., Lopes, F.S., 2008. Use of corticosteroid therapy on the modulation of uterine inflammatory response in mares after artificial insemination with frozen semen. Pferdeheilkunde 24, 79–82. Watson, E.D., Stokes, C.R., Bourne, F.J., 1988. Concentrations of immunoreactive leukotriene B4 in uterine lavage fluid from mares with experimentally induced and naturally occurring endometritis. J. Vet. Pharmacol. Ther. 11, 130–134.
Contents lists available at ScienceDirect
Animal Reproduction Science journal homepage: www.elsevier.com/locate/anireprosci
Abstract
Effect of post-insemination dexamethasone treatment on pregnancy rates in mares夽 H. Vandaele a,∗ , P. Daels a , S. Piepers b , M. LeBlanc c a b c
Keros AI and ET Center, Passendale, Belgium School of Veterinary Medicine, Ghent University, Ghent, Belgium Rood and Riddle Equine Hospital, Lexington, USA
1. Introduction Uterine inflammation is considered as a physiological response to the presence of semen in the uterus. In normal fertile mares, this inflammatory response ends approximately 36 h after mating but in susceptible mares the semen-induced inflammation lasts much longer. Persistent mating-induced endometritis may alter the uterine environment resulting in early embryonic loss. It has been suggested that modulation of this inflammatory response may improve fertility in susceptible mares. Bucca et al. (2008) examined the effect of dexamethasone in 347 mares over 513 estrous cycles and reported that a single dose of 50 mg dexamethasone given at the time of insemination did not have a deleterious effect on the pregnancy rate. They also observed a correlation between dexamethasone treatment and increased pregnancy rate in three subsets of mares: mares with three or more risk factors for endometritis, susceptible mares with more than 2 cm of uterine fluid after mating, and mares where intrauterine fluid persisted 36 h after mating. Others have reported increased pregnancy rates in subfertile mares with a history of post-insemination fluid accumulation when they are given prednisolone every 12 h beginning 24 h before mating and continuing until ovulation (Papa et al., 2008). As clinical signs of post-mating endometritis are not usually evident in mares until after insemination, and as the reproductive history is not always available, it is difficult
夽 This paper is part of the supplement entitled “Proceedings of the Tenth International Symposium on Equine Reproduction”, Guest Edited by Margaret J. Evans. ∗ Corresponding author. E-mail address: [email protected] (H. Vandaele). 0378-4320/$ – see front matter doi:10.1016/j.anireprosci.2010.04.074
to determine which mares should be treated with steroids before mating. Therefore, in clinical practice, steroids have been given after mating to mares with intrauterine fluid, but it is not known if this treatment improves pregnancy rates. The aim of this study was to determine if intravenous administration of dexamethasone after insemination increases pregnancy rates. 2. Materials and methods Client-owned mares (n = 774 cycles; 359 mares) presented for breeding at Keros AI and ET Center during the 2008 breeding season were assigned randomly to one of three treatment groups: T0 = no treatment (n = 327); T1 = 10 mg dexamethasone (Rapidexon® , Eurovet Animal Health, The Netherlands) given i.v. (n = 245); T2 = 20 mg dexamethasone (n = 202). The dexamethasone (Groups T1 and T2) was given 6–12 h after insemination. Each week one-treatment type was applied to all inseminated mares, except mares in competition. Treatments were repeated every 3 weeks between May 10 and August 31. Mares ranged in age from 2 to 28 years (mean age = 11 years). Mares were artificially inseminated either with cooled semen (n = 542 cycles) or frozen semen (n = 232 cycles). Mares received additional reproductive medical treatments after breeding as deemed necessary, including large volume uterine lavage, oxytocin, prostaglandin, intrauterine and/or systemic antibiotics and altrenogest. The amount of intrauterine fluid was noted before insemination and at 6–12 h after insemination. Pregnancy was diagnosed by ultrasonography at 14–17 days (US group; n = 419 cycles; 245 mares) or by embryo recovery on Day 7 or 8 after ovulation (ET group; n = 355 cycles; 114 mares). Data were analysed by logistic regression with pregnancy status as the binary dependent variable (0 = not pregnant;
H. Vandaele et al. / Animal Reproduction Science 121S (2010) S110–S112 Table 1 Pregnancy rates in mares treated 6–12 h after insemination with dexamethasone. DEX (mg)
US
ET flush
n
Preg
%
0 10 20
193 114 112
98 67 62
50.7 58.8 55.4
n 134 131 90
Table 3 Effect of age on pregnancy rate in mares treated with dexamethasone 6–12 h after breeding. DEX (mg)
Preg
%
61 57 41
45.5 43.5 45.5
US = ultrasound group, ET flush = mares for embryo flush, DEX = dose of dexamethasone given, n = number of mares, Preg = number of pregnant mares, % = pregnancy rate.
S111
US n
ET flush Preg
Less than 14 years of age 0 116 60 10 78 48 20 72 41 More than 14 years of age 0 77 38 10 36 19 20 40 21
%
n
Preg
%
51.7 61.5 56.9
89 86 66
44 40 31
49.4 46.5 47.0
49.3 52.7 52.5
46 45 23
17 17 9
37.0 37.7 39.1
Table 2 Pregnancy rates in mares with intrauterine fluid either before or after insemination treated with dexamethasone 6–12 h after insemination. DEX (mg)
US n
ET flush Preg
%
Intrauterine fluid before insemination 0 14 4 28.6 10 11 4 36.4 20 11 4 36.4 Intrauterine fluid after insemination 0 65 23 35.3 10 32 14 43.7 20 38 14 36.8
n
Preg
%
24 28 15
8 6 5
33.3 21.4 33.3
53 68 47
24 28 16
45.2 41.1 34.0
1 = pregnant), and treatment strategy, intrauterine fluid and mare age as categoric independent variables (SPSS16.0, SPSS Inc., Chicago, IL). All first-order interactions were tested and removed when non-significant statistical significance was assessed at P < 0.05. 3. Results Pregnancy rates per cycle were higher in the US group (54%, 227 pregnancies out of 419 cycles) than in the ET group (45%, 159 positive collections, one or more embryos, out of 355 cycles; P < 0.01). Therefore, the effect of dexamethasone was examined separately for the two groups. Dexamethasone treatment did not affect pregnancy rates in either group (Table 1). Also, dexamethasone treatment did not improve pregnancy rates in mares that had intrauterine fluid before or after insemination (Table 2). When considering all treated and non-treated mares combined, pregnancy rates were higher (P = 0.01) in mares that did not have intrauterine fluid before insemination (US group: n = 383 cycles; 56.1% and ET group: n = 288 cycles; 48.3%) than in mares with intrauterine fluid before insemination (US group: n = 36; 33.3% and ET group: n = 67; 28.4%; see Table 2). In addition, mares with fluid after insemination in the US group had lower pregnancy rates (n = 135; 37.8%; P = 0.001) than did US group mares without fluid after insemination (n = 284; 61.9%; Table 2). There was no effect of age on the efficacy of dexamethasone treatment (Table 3). 4. Discussion Unlike previous investigators, we did not observe an effect of dexamethasone on pregnancy rates when it was given after insemination either in the general population
of mares, in mares that had intrauterine fluid before or after breeding, or in aged mares. However, pregnancy rates were lower in mares with intrauterine fluid, regardless of treatment, than in mares without intrauterine fluid. Steroids block both the cyclo-oxygenase and 5-lipoxygenase pathways of inflammation. The 5lipoxygenase pathway includes leukotriene B, a potent neutrophil chemotactic factor found in uterine fluids of susceptible mares after mating (Watson et al., 1988). Reducing the neutrophil chemotaxis and the number of neutrophils recruited into the uterus post-mating may diminish the severity and length of the inflammatory response. Neutrophils migrate into the uterine lumen within minutes of insemination, peaking at 8–12 h postinsemination (Katila, 1995). Delaying dexamethasone administration until 6–12 h after insemination may not adequately inhibit or decrease neutrophil migration and the subsequent inflammatory response. Therefore it is possible that timing of treatment may have affected results. Bucca et al. (2008) and Papa et al. (2008) administered steroids before insemination while in this study dexamethasone was administered 6–12 h after insemination. In a clinical situation, it is often difficult to determine which mares should be treated with steroids before mating because many mares show no clinical signs of endometritis until later. Therefore a treatment that could be successfully implemented after insemination would have a considerable practical advantage. The dose of dexamethasone chosen in the present study (10 or 20 mg) is lower than in other studies because of concerns for adverse side effects such as laminitis. No adverse side effects were observed in the present study. Risk factors that may have adversely affected pregnancy rates in this study were restricted to age and the presence of fluid. The inclusion of more risk factors, as described by Bucca et al. (2008), might have identified a subset of mares in which dexamethasone treatment would have increased pregnancy rates in the present study. Clinical histories on many of the mares were either not precise or lacking and therefore were not included in the model. In conclusion, administration of 10 or 20 mg of dexamethasone 6–12 h after insemination did not improve pregnancy rates in mares bred with cooled or frozen semen, regardless of age or the presence of intrauterine fluid.
S112
H. Vandaele et al. / Animal Reproduction Science 121S (2010) S110–S112
Conflict of interest None. Acknowledgements The research was funded by the USDA-CSREES. The CpGODN used in this study was provided free of cost by Merial, Ltd. References Bucca, S., Carli, A., Buckley, T., Dolci, G., Fogerty, U., 2008. The use of dexamethasone administered to mares at breeding time in the modu-
lation of persistent mating induced endometritis. Theriogenology 70, 1093–1100. Katila, T., 1995. Onset and duration of uterine inflammatory response of mares after insemination with fresh semen. Biol. Reprod. Monogr. Ser. 1, 515–517. Papa, F.O., Alvarenga, J.A., Melo, M.A., Zahn, C.M., Lopes, F.S., 2008. Use of corticosteroid therapy on the modulation of uterine inflammatory response in mares after artificial insemination with frozen semen. Pferdeheilkunde 24, 79–82. Watson, E.D., Stokes, C.R., Bourne, F.J., 1988. Concentrations of immunoreactive leukotriene B4 in uterine lavage fluid from mares with experimentally induced and naturally occurring endometritis. J. Vet. Pharmacol. Ther. 11, 130–134.