Browsing by Author "Cuervo-Arango Lecina, Juan"

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  • Cuervo-Arango Lecina, Juan (Helsingin yliopisto, 2010)
    Cloprostenol, a prostaglandin F2α analogue, is commonly used for reproductive work in equine practice. Its main indications in equine reproduction are termination of the luteal phase and early pregnancy, evacuation of uterine fluid and induction of parturition. However, cloprostenol may be responsible for several other biological reproductive effects than the main indications of its use, which may influence the reproductive outcome and management of the mare. Moreover, these proposed side effects include advancement of ovulation, enhancement of follicular development, an increase in multiple ovulation rate and ovulatory failure in cyclic mares and a reduction in fertility. The objective of this study was largely the characterization of these side effects observed in a clinical setting of equine practice and to determine their impact on the reproductive management of mares. Records from clinical observations of ovarian and uterine ultrasonography, treatment protocols and reproductive management of mares were obtained from two types of settings: a commercial Thoroughbred stud farm and a veterinary clinic. These data were analyzed retrospectively to determine and characterize some of the side effects of cloprostenol associated with its clinical use in inducing oestrus in mares. Mares which ovulated spontaneously had similar preovulatory follicular diameters in two consecutive cycles. However, when the consecutive oestrus was induced by cloprostenol, the follicular diameter decreased significantly, which was probably due to an enhanced follicular maturation rate. Treatment of dioestrous mares with cloprostenol, who had relatively large follicles resulted in higher uterine oedema scores in the peri-ovulatory period than mares who had returned to oestrus spontaneously. Cloprostenol dose and follicular diameter at the time of treatment significantly affected the interval from treatment to ovulation. Higher cloprostenol doses from 125 µg upwards and large follicles at the time of treatment resulted in shorter intervals to ovulation. Mares treated with cloprostenol on day 5 to 7 post-ovulation with an interval from treatment to ovulation >7 days, had a higher multiple ovulation rate than mares with either a shorter interval from treatment to ovulation or those that ovulated spontaneously. Fertility of mares mated and ovulated soon after cloprostenol treatment (4 to 7 days) was reduced by about 20 to 30% compared to mares with longer intervals or to untreated mares. Mares were more likely to develop haemorrhagic anovulatory follicles during oestrus after having had cloprostenol treatment than during spontaneous cycles. The incidence of haemorrhagic anovulatory follicles was lower during the winter and early spring and increased during the summer months. The age of the mare did not significantly affect the occurrence of haemorrhagic anovulatory follicles. In conclusion, the use of cloprostenol in a clinical setting is associated with different side effects that are undesirable for equine fertility and management in most cases. The majority of these side effects are associated with hormonal changes resulting from induced luteolysis at non-physiological stages of the oestrous cycle.