title: Relationship between the timing of prostaglandin-induced luteolysis and effects on the conceptus during early pregnancy in mares.
abstract: To advance the understanding of early pregnancy and pregnancy failure in horses, this study determined how luteolysis induced by cloprostenol (an analogue of prostaglandin F2α) affects conceptus development. Mares were injected on Days 12, 14, 16 or 18 of pregnancy with either cloprostenol (treatment groups, total n=83 pregnancies) or saline (controls, n=81), and growth of the conceptuses was monitored and compared by daily ultrasonography until they were collected transcervically on Days 15-22, 1-4 days after the injections. The comparisons were extended in the recovered conceptuses by counting somites, measuring the volume and osmolality of yolk-sac fluid and its concentrations of proteins, estrone sulfate and progesterone, and by assessing the morphology of the capsule and vascular system. When luteolysis was initiated on or before Day 16, most pregnancies survived until the time of collection and the conceptuses in respective treated and control groups on Days 15-20 were very similar except for some effects of treatment on the capsule and vascular development. In contrast, after luteolysis was initiated on Day 18, abortion often ensued within 3 days and most conceptuses collected had degenerated, therein constituting a predictable system in which to study the pathogenesis of a particular cause of pregnancy failure.
authors.affiliation: Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada. kbetter@uoguelph.ca
authors.forename: Keith J
authors.initials: KJ
authors.lastname: Betteridge
authors.forename: Rudolf O
authors.initials: RO
authors.lastname: Waelchli
authors.forename: Heather L
authors.initials: HL
authors.lastname: Christie
authors.forename: James I
authors.initials: JI
authors.lastname: Raeside
authors.forename: Bette A
authors.initials: BA
authors.lastname: Quinn
authors.forename: M Anthony
authors.initials: MA
authors.lastname: Hayes
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000502:physiology; D003008:Cloprostenol / Q000008:administration & dosage / Q000494:pharmacology; D015237:Dinoprost / Q000031:analogs & derivatives / Q000494:pharmacology* / Q000502:physiology; D047108:Embryonic Development / Q000187:drug effects / Q000502:physiology; D005260:Female; D005300:Fertility Agents, Female / Q000008:administration & dosage / Q000494:pharmacology; D005865:Gestational Age; D006736:Horses / Q000378:metabolism / Q000502:physiology*; D003341:Luteolysis / Q000187:drug effects* / Q000502:physiology; D011247:Pregnancy; D011258:Pregnancy Tests / Q000379:methods / Q000662:veterinary; D011270:Pregnancy, Animal; D013997:Time Factors; D014463:Ultrasonography
chemical_list: D005300:Fertility Agents, Female; D003008:Cloprostenol; D015237:Dinoprost