Equine Fertility Clinic

Brownhills, United Kingdom

Equine Fertility Clinic

Brownhills, United Kingdom
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Newcombe J.R.,Equine Fertility Clinic | Paccamonti D.,Louisiana State University | Cuervo-Arango J.,CEU Cardenal Herrera University
Animal Reproduction Science | Year: 2011

Data were analysed retrospectively from fourteen breeding seasons at an Equine Fertility Clinic for the effect of interval between pre- and postovulatory examinations for immediate postovulatory insemination on pregnancy rate (PR) and embryo loss rate (ELR). Mares of various breeds and ages were examined at intervals which varied from 0.5 to 15 h between the pre- and postovulatory period over 867 cycles. When ovulation was detected they were inseminated with a single dose of commercial frozen-thawed semen. All mares were treated in the post-insemination period with intrauterine antibiotics and then with oxytocin. Pregnancy diagnoses were made at 12-17 days post-ovulation and at intervals up to 40 days. The overall PR was 47.9%. The data were pooled into 3 h examination intervals. In the first interval, mares were inseminated at the time of ovulation to 3 h post-ovulation (n= 44) with a PR of 43.2%. Results of insemination to consecutive 3 h intervals gave PR of 44.7% (3-6 h, n= 150), 45.1% (6-9 h, n= 432), 55.8% (9-12 h, n= 190) and 54.9% (12-15 h, n= 51). ELR was 10.5%, 11.9%, 5.6%, 7.5% and 3.6% respectively for the same intervals. There was no statistical difference in either the PR or ELR. It is concluded that in a postovulatory insemination regime with routine post-insemination treatment as described, examination of mares at intervals of any less than 12-15 h does not improve pregnancy or embryo loss rates. © 2010 Elsevier B.V.


Cuervo-Arango J.,CEU Cardenal Herrera University | Newcombe J.R.,Equine Fertility Clinic
Reproduction in Domestic Animals | Year: 2010

Prostaglandin F 2α and its analogues (PGF) are widely used in equine reproductive practice. The interval from PGF treatment to ovulation (ITO) varies greatly with a range from 2 to 16 days. Clinical observation suggests that mares mated and ovulated soon after PGF treatment may have poor fertility. Reproductive records of 329 cyclic Thoroughbred mares were analysed retrospectively. The following parameters were analysed: (i) use of cloprostenol; (ii) ITO and (iii) number of ovulations per cycle. According to these parameters, mares were classified into four groups. (i) mares with spontaneous ovulations, n = 57; (ii) mares induced with cloprostenol and ITO = 4-7 days, n = 77; (iii) ITO = 8-10 days, n = 89 and (iv) ITO = ≥11 days, n = 106. Differences in pregnancy (PR) and multiple ovulation (MO) rates among groups were tested using chi-squared test. PR rates for groups 1-4 were: 73.7%, 46.7%, 64% and 71.7% respectively (p < 0.05). Groups 1 and 2 had lower (p < 0.05) MO rate (24.6% and 20.8%) than groups 3 and 4 (40.4% and 44.3%). It appears that ovulation soon after PGF-induced luteolysis is detrimental to PR rates. It was found highly significant that in cloprostenol-treated mares, the MO rate was enhanced without subsequent increase in multiple pregnancies. © 2009 Blackwell Verlag GmbH.


Cuervo-Arango J.,Equine Fertility Clinic | Cuervo-Arango J.,CEU Cardenal Herrera University | Newcombe J.R.,Equine Fertility Clinic
Reproduction in Domestic Animals | Year: 2012

Contents: The objective of this study was to establish and characterize the relationship between the dose of cloprostenol (37.5, 250, 500 and 750μg) and the age of the early corpus luteum (CL) (80, 88, 96, 104 and 112h) on the luteolytic response of mares. Behavioural oestrus and ultrasonographic signs of return to oestrus were considered as the occurrence of full luteolysis. A total of 298 mares were divided into groups according to dose of cloprostenol and CL age. There was an effect of dose of cloprostenol (p<0.001) and age of the CL at the time of treatment (p<0.001) on the percentage of mares with full luteolysis. The efficacy of 37.5μg of d-cloprostenol was similar to that of 250 μg of d,l-cloprostenol (p > 0.05); and that of 500 similar to that of 750μg (p>0.05). The higher dose groups (500 and 750μg) induced full luteolysis more frequently than the lower dose groups (37.5 and 250μg) 96-104h post-ovulation. There was no effect of CL age or cloprostenol dose on the interovulatory interval (p>0.05). In conclusion, the effect of cloprostenol on the percentage of mares undergoing full luteolysis is dose-dependent. However, this effect is only evident in mares with CLs aged between 96 and 104h. There is no advantage of administering more than 500μg of d,l-cloprostenol (Estrumate ®), to obtain a higher percentage of mares with full luteolysis in mares with CLs aged 80-112h. © 2011 Blackwell Verlag GmbH.


Davies Morel M.C.G.,Aberystwyth University | Newcombe J.R.,Equine Fertility Clinic | Hayward K.,Aberystwyth University
Theriogenology | Year: 2010

The importance of elucidating factors affecting reproductive performance and efficiency is of paramount concern to the equine industry. Oocyte viability is known to be one of the determinants of reproductive success and evidence suggests that it may be linked to follicle size. The aims of this study were, therefore, to ascertain: i) the average diameter and range of pre-ovulatory follicles in Thoroughbred mares; ii) whether this is affected by either mare age, time within the breeding season, or the presence of multiple pre-ovulatory follicles (MO). One thousand, four hundred and ninety two Thoroughbred mares, aged 2-26 years, were examined with ultrasound to ascertain ovulation date to within 24h, and pre-ovulatory follicle(s) (F1) diameter. Mares were divided into groups according to age (7 groups, 2-4 yr, 5-7 yr, 8-10 yr, 11-13 yr, 14-16 yr, 17-19 yr, >19 yr), time within the season (16 half-month groups, from Feb 1st to Sept 30th), and pre-ovulatory follicles (single, {SO} or multiple {MO}). Overall average F1 diameter was 39.95 ± 4.84 mm (range 22-50 mm). Mare age had a significant (P < 0.001) negative effect on F1 diameter (largest F1 38.95 ± 5.61 mm, mares 2-4 yrs; smallest F1 33.30 ± 4.66 mm, mares >19 yrs) as did season (largest F1 44.20 ± 3.95 mm, Feb 1st-14th; smallest F1 33.74 ± 4.87 mm, Aug 15th-31st) and the presence of more than one pre-ovulatory follicle (MO F1 35.45 ± 4.53 mm; SO F1 37.44 ± 4.84 mm). In conclusion older mares, bred towards the end of the breeding season, especially if MO were present, were more likely to ovulate from smaller follicles. If, as suggested, small pre-ovulatory follicle size is associated with low oocyte viability, then this may account, at least in part, for the poor fertility rates characteristic of older MO mares, bred later in the season and so justify increased monitoring and careful reproductive management of such mares. © 2010 Elsevier Inc.


Davies Morel M.C.G.,Aberystwyth University | Newcombe J.R.,Equine Fertility Clinic | Lauber M.,Aberystwyth University
Veterinary Journal | Year: 2012

To determine whether manually reduced multiple pregnancies (MPs) are at a greater risk of pregnancy loss than single pregnancy (SP) in mares, and to examine if a difference exists in the timing of pregnancy loss between manually reduced MPs and SPs, 1916 Thoroughbred mares were ultrasonically monitored every 2. days during oestrus to confirm ovulation, and up to Day 40 post-ovulation to confirm pregnancy. Ultimate pregnancy outcome was ascertained from the General Thoroughbred Stud book and classified as live foal (LF), early abortion (EA; Days 40-150), slipped foal (SF; Days 150-term), and barren (B; Time of pregnancy loss unknown).Significantly (P< 0.05) more SPs failed (17.23%; 226/1312) than manually reduced MPs (13.41%; 81/604). Both SPs and MPs were at greatest risk of being lost as EA (72.16%; 127/176 and 61.67%; 37/60, respectively) compared to SF (27.84%; 49/176 and 38.33%; 23/60). There was no significant difference in the time of greatest risk of pregnancy loss between manually reduced MPs and SPs. It was concluded that owners and veterinarians can be assured that manual reduction of MPs does not increase the risk of pregnancy loss above those associated with SPs. © 2011 Elsevier Ltd.


Newcombe J.,Equine Fertility Clinic | Cuervo-Arango J.,CEU Cardenal Herrera University
Reproduction in Domestic Animals | Year: 2011

Contents: One hundred and fifty-four mares were inseminated with fresh semen either during the pre- or post-ovulatory periods at different intervals relative to ovulation: 36-24h (n=17) and 24-0h (n=30) before ovulation; 0-8h (n=21), 8-16h (n=24), 16-24h (n=48) and 24-32h (n=14) h after ovulation. All mares received the same routine post-mating treatment consisting of an intrauterine infusion with 1litre of saline and antibiotics followed 8h later by an intravenous administration of oxytocin. Artificial inseminations (AI) from 36h before ovulation up to 16h post-ovulation were performed with transported cooled semen. While there was no data available for inseminations later than 16h, data from natural mating after 16h post-ovulation were included. Pregnancy rate (PR) of mares inseminated 36-24h (29.4%) was significantly lower (p<0.05) than mares inseminated 24-0h before ovulation (60%), 0-8h (66.7%) and 8-16h (70.1%) post-ovulation. Embryo loss rate (ELR) was highest in mares mated 24-32h after ovulation (75%). PR of mares mated 16-24h post-ovulation (54.1%) did not differ significantly from any other group (p>0.05); however, the ELR did increased markedly (34.6%) compared with inseminations before 16h post-ovulation (<12%). At ≥30days post-ovulation, PR of mares mated 16-24h after ovulation (35.4%) was significantly lower than mares mated 0-16h after ovulation (62%). Good PR with acceptable ELR can result from inseminations within 16h of ovulation, at least with this specific post-mating routine treatment. © 2010 Blackwell Verlag GmbH.


Cuervo-Arango J.,Royal Veterinary College University of London | Newcombe J.R.,Equine Fertility Clinic
Reproduction in Domestic Animals | Year: 2010

Contents: Haemorrhage into the dominant follicle during the reproductive season is a subtle but definitive cause of infertility in the mare population. This condition however can be of high relevance for an individual in which its incidence is abnormally high. Little is known about the nature and factors affecting the incidence of haemorrhagic anovulatory follicles (HAFs) in the mare. The objectives of the study were to define and characterize the ultrasonographic development and incidence of HAFs and to investigate possible risk factors influencing its occurrence. Detailed reproductive and ultrasound records of seven mares studied during their entire reproductive lives (>10 years and 612 oestrous cycles) were analysed retrospectively and computed into a statistical mixed model. Of all animal studied, two mares were found to have an unusually high incidence of HAFs of approximately 25%. Time of season and use of induction treatments (Cloprostenol) were found to influence its incidence. It appears that early-enhanced stimulatory effect of LH on an ovary with the presence of small and immature follicles might increase the risk of ovulatory failure of those follicles later in the cycle. Mares during the months of highest follicular activity (May to August) and after treatment with hormones to induce oestrus and ovulation are at greater risk to develop HAFs. The potential relevance of this study is two folds: clinical relevance for the practitioner to better understand this condition and so improve reproductive management of mares with abnormally high incidence; and to provide useful insights for researchers willing to further investigate the nature of this phenomenon. © 2008 The Authors. Journal compilation © 2008 Blackwell Verlag.


PubMed | Equine Fertility Clinic
Type: Journal Article | Journal: Reproduction in domestic animals = Zuchthygiene | Year: 2012

The objective of this study was to establish and characterize the relationship between the dose of cloprostenol (37.5, 250, 500 and 750 g) and the age of the early corpus luteum (CL) (80, 88, 96, 104 and 112 h) on the luteolytic response of mares. Behavioural oestrus and ultrasonographic signs of return to oestrus were considered as the occurrence of full luteolysis. A total of 298 mares were divided into groups according to dose of cloprostenol and CL age. There was an effect of dose of cloprostenol (p < 0.001) and age of the CL at the time of treatment (p < 0.001) on the percentage of mares with full luteolysis. The efficacy of 37.5 g of d-cloprostenol was similar to that of 250 g of d,l-cloprostenol (p > 0.05); and that of 500 similar to that of 750 g (p > 0.05). The higher dose groups (500 and 750 g) induced full luteolysis more frequently than the lower dose groups (37.5 and 250 g) 96-104 h post-ovulation. There was no effect of CL age or cloprostenol dose on the interovulatory interval (p > 0.05). In conclusion, the effect of cloprostenol on the percentage of mares undergoing full luteolysis is dose-dependent. However, this effect is only evident in mares with CLs aged between 96 and 104 h. There is no advantage of administering more than 500 g of d,l-cloprostenol (Estrumate()), to obtain a higher percentage of mares with full luteolysis in mares with CLs aged 80-112 h.


PubMed | University Utrecht, Equine Fertility Clinic and CEU Cardenal Herrera University
Type: Journal Article | Journal: Theriogenology | Year: 2016

The interval from both spontaneous and prostaglandin (PGF)-induced luteolysis to ovulation is greatly variable in mares. Several reports have shown a positive association between the length of the interval from PGF treatment to ovulation (ITO) and the subsequent pregnancy rate (PR). However, it is not known whether this association also occurs in estrous cycles with spontaneous luteolysis. The main objective of this study was to determine the effect of the duration of estrus-like echotexture of the uterus during the follicular phase on the subsequent PR in both spontaneous and PGF-induced cycles. A total of 768 estrous cycles from 325 thoroughbred mares were analyzed (401 estruses were induced with exogenous PGF and 367 cycles were not treated with PGF). The following factors were taken into account to determine the effect on PR: age of the mare, stallion, year of breeding, month of season, reproductive status of the mare, use of PGF treatment, duration of follicular phase with estrus-like echotexture, interovulatory interval (IOI; in spontaneous cycles), and ITO (in PGF-induced cycles). The age of the mare (P=0.017), mare status (P=0.031), the ITO (P=0.041), and the duration of the follicular phase with estrus-like echotexture (P<0.001) influenced the PR. The PR increased with the duration of estrus and of endometrial edema in both PGF-induced and spontaneous cycles. The correlation between the duration of endometrial edema and the IOI and ITO was positive (r=0.5) and significant (P<0.05).


PubMed | Equine Fertility Clinic
Type: Journal Article | Journal: Irish veterinary journal | Year: 2013

It is believed that during the spring transition, the developing follicle tends to grow more slowly, persist longer and grow to a larger diameter prior to ovulation than at subsequent oestrus periods. A general suspicion, that the first ovulation of the year is less fertile than subsequent ovulations could be explained by a slower growth rate of the ovulatory follicle during transition with the consequent production of a subfertile oocyte. By detailed serial examination of the same group of Irish Draught mares over three winter/spring periods, no significant difference was found in either growth rate or pre-ovulatory diameter when compared with subsequent ovulations. Mean growth rates over the ten days prior to ovulation were 2.20 mm/day (range 1.18 to 3.64) and 2.19 mm/day (range 1.25 to 3.41) for first and subsequent ovulations respectively. Mean maximum pre-ovulatory diameters were 44.7 mm (range 35 to 59) and 43.5 mm (range 31 to 57.5) for first and subsequent ovulations respectively. The impression gained by practitioners that the first follicle develops more slowly during the transition to the first ovulation of the season may be due to less frequent examinations and consequently a failure to observe and record that follicles may grow and then regress during this period. The largest follicle observed a few days previously is not necessarily the same large follicle found at a later examination.

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