Omneity® Pellets
All-In-One Vitamin & Mineral Pellet
Topic:Progesterone
Progesterone is a steroid hormone produced primarily by the ovaries in mares and plays a significant role in the reproductive system of horses. It is involved in the regulation of the estrous cycle and the maintenance of pregnancy. Progesterone levels fluctuate throughout the reproductive cycle, influencing reproductive behavior and physiology. In veterinary medicine, measuring progesterone levels can aid in diagnosing reproductive conditions and managing breeding programs. This page compiles peer-reviewed research studies and scholarly articles that explore the production, regulation, and clinical applications of progesterone in equine reproductive health.
Diestrous Ovulations in Pregnant Mares as a Response to Low Early Postovulatory Progestogen Concentration. Spontaneous prolongation of the luteal phase has been described in horses, but the underlying causes are still unclear. The present study investigated details of gonadotrophin and progestogen secretion in pregnant mares (n = 11) with or without experimentally reduced early postovulatory luteal function. From days 0 to 3 after ovulation, they were treated with the prostaglandin F (PGF) analogue cloprostenol or left untreated. After conceptus collection on day 34, they were assigned to the opposite treatment. Mares were affiliated to the group primary corpus luteum (n = 6) or diestrous corpus lu...
Serum Progesterone and Conception Rates in Acyclic Embryo Recipient Mares Using a Bovine Progesterone-Releasing Intravaginal Device. The objective of this study was to quantify serum progesterone levels, uterine features, and pregnancy rates in acyclic, embryo recipient mares using a bovine progesterone-releasing intravaginal device in a commercial embryo transfer (ET) program. The study included 73 recipient mares of unknown breed, aged 3-10 years, weighing 350-500 kg, and kept under an intensive management system on Tifton 85 (Cynodon spp.) pastures with water and mineral salt ad libitum. The horses were divided into two groups: a group with a progesterone-releasing intravaginal device (1 g progesterone, G-IVP4, n = 24...
Ultrasound-guided aspiration of dominant follicles (≥25 mm) followed by luteinization and progesterone production during the estrous cycle in mares. The present study was designed to evaluate luteinization rates subsequent to aspiration of dominant follicles (≥25 mm) in the absence of a functional CL (progesterone 0.05) at 83, 67, 83, and 100%, respectively. Correspondingly, progesterone concentrations increased (>2 ng/mL) by approximately 6, 7, 5, and 4 d after aspiration, respectively, which were delayed (P < 0.05) in the 25-29 and 30-34 mm follicle aspiration groups compared to 2 d after ovulation in the control group. Thereafter, progesterone reached maximal concentrations (10-11 ng/mL) as averaged over all aspiration...
Structural and functional analysis of the inhibition of equine glutathione transferase A3-3 by organotin endocrine disrupting pollutants. Organotin compounds are highly toxic environmental pollutants with neurotoxic and endocrine-disrupting effects. They are potent inhibitors of glutathione transferases (GSTs), thus impeding their detoxication and antioxidant functions. Several GSTs, including equine GST A3-3 (EcaGST A3-3), exhibit steroid double-bond isomerase activity and are involved in the biosynthesis of testosterone and progesterone. We have performed enzyme kinetics analyses of the inhibition of EcaGST A3-3 by organotin compounds. We have also solved crystal structures of EcaGST A3-3 in complexes with glutathione, and wit...
Unravelling androgens in sport: Altrenogest shows strong activation of the androgen receptor in a mammalian cell bioassay. Altrenogest is a commonly used progestogen for the suppression of oestrus and associated distracting behaviours that interfere with training and performance of female racehorses. The steroid is derived from 19-nor testosterone and is structurally similar to the anabolic androgenic steroid, trenbolone. In this study, the relative androgen potency of altrenogest was determined by a kidney (HEK293) cell androgen bioassay. The HEK293 bioassay shows that in its pure form, altrenogest has a high relative potency compared with testosterone but is not as strong as β-trenbolone. Our results also show ...
Active immunisation against GnRH as treatment for unilateral granulosa theca cell tumour in mares. Stallion-like or aggressive behaviour in mares affected by unilateral granulosa theca cell tumour (GTCT) is well-known, but use of a GnRH-vaccine as an alternative to surgical removal of the neoplastic ovary has not been investigated. Objective: To determine the effect of immunisation against GnRH on ovarian size, testosterone concentration, Anti-Müllerian hormone (AMH) concentration, and owner-reported behaviour in four mares affected by unilateral GTCT. Methods: Retrospective case report. Methods: A presumptive diagnosis of GTCT was made in four mares based on clinical signs, behavioural ch...
Differences in Endocrine and Cardiac Changes in Mares and Her Fetus before, during, and after Parturition in Horses of Different Size. Equine fetomaternal monitoring is based on endocrine and cardiac parameters which may differ among small, medium-size, and full-size horses. Therefore, Shetland ( = 6), Haflinger ( = 8), and Warmblood pregnancies ( = 9) were studied during late gestation and at foaling. Weight of mares, foals and placenta, plasma progestin and cortisol concentration, heart rate and heart rate variability (HRV) were determined. Foal weight always approximated 10% of mare weight but relative placenta weight was highest in full-size mares ( < 0.05). Progestin ( < 0.001) and cortisol ( < 0.05) concentrati...
Functional response of systemic and intrafollicular placental growth factor in cycling mares. The aim of the study was to assess the physiological reference values for systemic and intrafollicular placental growth factor (PlGF) concentrations in different categories of follicular sizes in cycling mares, according to progesterone (P4) and oestradiol (E2) patterns. Sixty ovaries were taken after slaughter from 30 clinically healthy mares. Regarding their size, the follicles were classified into three different categories, i.e. small (20-30 mm), medium-sized (31-40 mm) and large (≥41 mm), and follicular fluid (FF) was sampled from each single follicle. Intrafollicular PlGF concentration...
Effects of Equine Chorionic Gonadotropin on Ovulatory and Luteal Characteristics of Mares Submitted to an P4-Based Protocol of Ovulation Induction With hCG. The aim of this study was to evaluate the effect of equine chorionic gonadotropin (eCG) at the end of progesterone (P4) treatment on follicular and luteal characteristics during transition period (TP) and reproductive breeding season (RP). A total of 13 crossbred mares were distributed in two experimental groups in the spring and summer (n = 26). The animals received intravaginal P4 (1.9 g) releasing device from D0 to D10. On removal of P4 device, the mares received 400 IU of eCG (eCG group) or saline solution (control group). Human chorionic gonadotropin (hCG; 1.750 IU) was administered (Dh...
Transient suppression of ovulatory ovarian function in pony mares after treatment with slow-release deslorelin implants. Behavior during the estrous cycle of mares can affect their performance and therefore inhibition of cyclical ovarian activity is indicated. We hypothesized that implants containing the GnRH analog deslorelin downregulate GnRH receptors and inhibit ovulation in mares. The estrous cycles of Shetland mares were synchronized with 2 injections of a PGF analog. One day after the second injection (day 0), mares received 9.4 (group D1, n = 6) and 4.7 mg deslorelin (D2, n = 5) as slow-release implants or 1.25 mg short-acting deslorelin as a control (C, n = 5). Ultrasonography of the reproductive trac...
Hormonal Stimulation in a Gonadal Dysgenesis Mare. The present case report aimed to determine the responsiveness of the endometrium and the ovaries of an X0 mare after hormonal treatment. On transrectal palpation, the uterus was flaccid and smaller than normal, and the ovaries were small and smooth. The endometrium had normal histological architecture, with an atrophic glandular epithelium. A karyotype evaluation was performed, and 70 cells presented 63 chromosomes, lacking one sex chromosome. Circulating hormonal levels of total estrogens were 43.93 pg/mL; progesterone 0.01 ng/mL; testosterone 48 pg/mL; FSH 30.3 ng/mL; and LH 1.71 ng/mL. ...
P4/E2-based protocol for synchronisation of ovulation of mares during the breeding and non-breeding season. Dispersed ovulation at the breeding (BS) and anestrus at non-breeding season (NBS) are major impediments to embryo transfer and insemination programmes. The present study aimed to evaluate a hormonal P4/E2-based synchronisation protocol in mares during both the BS and the NBS on ovarian/follicle behaviour. Mares underwent a hormone protocol to synchronise their ovulation during the BS (n = 8) and NBS (n = 10), starting (D0) with the insertion of an intravaginal device containing 1 g of P4 and 7 mg Estradiol Benzoate IM. (EB). On D9, the device was removed and injected with 0.25 mg o...
Comparative efficiency of oestrus synchronization in sheep with progesterone/eCG and progesterone/GnRH during breeding and non-breeding season. The present study compared the occurrence of oestrus behaviour and ovulation in response to the insertion of CIDR devices plus a classical treatment with equine chorionic gonadotrophin (eCG; single dose at CIDR removal) or alternative treatments with gonadotrophin-releasing hormone (GnRH, either in a single dose at 56 hr after CIDR removal, or in one dose at CIDR insertion and another dose at 56 hr after CIDR removal). The appearance of oestrus behaviour during reproductive season ranged between 84% and 95% and all females showing oestrus signs had subsequent ovulations. The response, during...
Modulation of the renin-angiotensin-aldosterone system by steroid hormones during the oestrous cycle in mares. In women and females of different species of laboratory animals, oestrogens stimulate the renin-angiotensin-aldosterone system (RAAS) by increasing tissue and circulating levels of angiotensinogen and renin during the preovulatory period. Progesterone and cortisol compete with aldosterone for mineralocorticoid receptors, which results in increased Na+ reabsorption during the postovulatory period. The purpose of the current research was to analyse the relationship of oestradiol-17β, progesterone and cortisol with RAAS in 23 mares during an oestrous cycle. During the preovulatory period, signif...
Luteinizing hormone and ovarian steroids affect in vitro prostaglandin production in the equine myometrium and endometrium. Prostaglandins (PGs) play crucial roles in the regulation of the oestrus cycle and establishment of pregnancy in animals. Luteinizing hormone (LH) and ovarian steroids are involved in regulating endometrial PG production in many species. Their effects on PG production and associated pathways in the mare myometrium and endometrium are the subjects of our interest. This study aimed to evaluate the specific effects of LH and ovarian steroids on equine myometrial and endometrial tissues on (i) PGE and PGF secretion and (ii) transcription of genes encoding specific enzymes responsible for PG synthe...
Spectral Doppler ultrasound in selecting an equine embryo receiver. The aim of this study was to evaluate whether the RI and PI values would help in choosing the best embryo recipient, and observe whether CL vascularization would influence P4 production. During the breeding season 2018/2019, the study was conducted using 35 mares, which is used for reference to collect data for the project on the day of embryo transfer. The utilized mares were divided into five groups followed by the day after ovulation, with D0 being the day of ovulation. Therefore, the five groups are as follows: D4-mares that were on the 4th post-ovulation day; D5-mares that were on the 5th...
The inhibitory influence of toluene on mare ovarian granulosa cells can be prevented by fennel. The influence of environmental contaminant toluene and of plant fennel (Foeniculum vulgare Mill.) on reproduction are reported, but the mechanisms of their action and the protective effect of fennel on contaminant influence remain to be elucidated. In this study, we hypothesized that toluene and fennel directly affects basic ovarian cell functions, and that fennel can be used as an appropriate natural protective agent against the potential adverse effects of toluene. This study aimed to examine the action of toluene (20 μg/mL) and fennel extract (0, 1, 10, 100 μg/mL), and assess their comb...
Asynchronous Embryo Transfer Followed by Comparative Transcriptomic Analysis of Conceptus Membranes and Endometrium Identifies Processes Important to the Establishment of Equine Pregnancy. Preimplantation horse conceptuses require nutrients and signals from histotroph, the composition of which is regulated by luteal progesterone and conceptus-secreted factors. To distinguish progesterone and conceptus effects we shortened the period of endometrial progesterone-priming by asynchronous embryo transfer. Day 8 embryos were transferred to synchronous (day 8) or asynchronous (day 3) recipients, and RNA sequencing was performed on endometrium and conceptuses recovered 6 and 11 days later (embryo days 14 and 19). Asynchrony resulted in many more differentially expressed genes (DEGs) in ...
Effect of Chronic Administration of Oxytocin on Corpus Luteum Function in Cycling Mares. The objective of this study was to determine if intramuscular administration of 60 units of oxytocin once daily for 29 days, regardless of when treatment was initiated during the estrous cycle (i.e., without monitoring estrous behavior and/or detecting ovulation), would induce prolonged corpus luteum (CL) function in cycling mares. Mares were randomly assigned to two groups: (1) saline-treated control (n = 7) and (2) oxytocin-treated (n = 9) subjects. Control mares received 3 cc of saline, and oxytocin-treated mares received 60 units (3 cc) of oxytocin intramuscularly for 29 consecutive d...
Impact of the corpus luteum on survival of the developing embryo and early pregnancy in mares. It has been more than a hundred years that studies aiming to elucidate the processes involved in cyclicity and pregnancy pointed out the requirement of ovaries and corpora lutea for embryo survival and pregnancy establishment. For horses, luteal progesterone is essential for pregnancy only during the first trimester. This progestational support is complex among domestic animals as ovarian luteal function is further enhanced by the LH-action role of equine chorionic gonadotropin (eCG) starting ∼ on Day 35 of pregnancy. Increased eCG secretion leads to the formation of supplementary corpora ...
Steroid synthesis and metabolism in the equine placenta during placentitis. Equine placentitis is associated with alterations in maternal peripheral steroid concentrations, which could negatively affect pregnancy outcome. This study aimed to elucidate the molecular mechanisms related to steroidogenesis and steroid-receptor signaling in the equine placenta during acute placentitis. Chorioallantois (CA) and endometrial (EN) samples were collected from mares with experimentally induced placentitis (n = 4) and un-inoculated gestationally age-matched mares (control group; n = 4). The mRNA expression of genes coding for steroidogenic enzymes (3βHSD, CYP11A1, CYP17A1, CYP19...
Birth of first foals through embryo transfer after artificial insemination using frozen semen in Japan. Until now, there have been no reports of foals born through embryo transfer after artificial insemination using frozen semen in Japan. The aims of this study were to develop a riding crossbred horse and evaluate the prospects of embryo transfer technology in multiplying horse population. In both donor and recipient mares, luteolysis was induced by the administration of 0.1 mg Cloprostenol to synchronize the onset of estrus, and ovulation was induced by administering 2000 IU human chorionic gonadotropin (hCG) or 0.75 mg Deslorelin. Frozen semen from an Irish Connemara pony stallion was used to ...
Reactive oxygen species are involved in the signaling of equine sperm chemotaxis. Sperm chemotaxis may facilitate the finding of the oocyte. Only capacitated spermatozoa can orient their movement by chemotaxis, which as well as capacitation, is regulated in part by the cAMP-PKA pathway. Reactive oxygen species (ROS) are produced during sperm capacitation which is closely related to chemotaxis. Then, the ROS participation in the chemotactic signaling can be expected. Here we studied the role of ROS in the chemotaxis signaling of equine spermatozoa which produce high quantities of ROS because of their energy metabolism. The level of capacitated and chemotactic spermatozoa was...
Secretion of equine chorionic gonadotropin and its association with supplementary corpus luteum formation and progesterone concentration in Hokkaido native pony recipient mares. The objectives of this study were to determine the plasma profile of equine chorionic gonadotropin (eCG) and its association with the formation of supplementary corpus luteum (CL) and plasma progesterone concentrations in embryo transfer Hokkaido native pony recipient mares. Blood samples and transrectal ultrasound examination of the reproductive tract were carried out weekly from the day of ovulation until week 32 of gestation (n = 4). Plasma concentrations of eCG and progesterone were measured by enzyme immunoassays. The eCG concentration was first detectable at week 5 for 2 mares and at wee...
The mule (Equus mulus) as a recipient of horse (Equus caballus) embryos: Comparative aspects of early pregnancy with mares. The aim of this study was to compare the embryonic and early fetal development of horse embryos between recipient mules and mares from day 10-60 of pregnancy, in addition to hormonal (eCG and progesterone), ovarian, and uterine characteristics for approximately 4 months. Embryo donor mares (n = 5) and two groups of recipients (acyclic mules, n = 7; cyclic mares, n = 7) were used. Donor mares were monitored daily by transrectal ultrasonography and inseminated using fresh semen. Cyclic recipient mares were synchronized with the donor's ovulation using PGF2α and deslorelin acetate. M...
Effect of hCG application at different moments of the estrous cycle on corpus luteum and uterine vascularization and serum progesterone concentration in mares. Establishment of pregnancy after embryo transfer is the ultimate goal of an embryo transfer program and increasing pregnancy rates and reducing pregnancy loss are mandatory. The utilization of treatments to improve conception rates in recipient mares has been the focus of several research groups over the last years and the results are controversial. Some studies using human chorionic gonadotrophin (hCG) found promising results. Our hypothesis was that hCG administration would cause an additional stimulation on luteal function, uterine and luteal vascularization and progesterone concentration, ...
Uterine cervix as a fundamental part of the pathogenesis of pregnancy loss associated with ascending placentitis in mares. Anatomical and molecular changes in the cervical barrier in women are a fundamental part of the pathogenesis of pregnancy loss associated with chorioamnionitis. However, there is little information regarding changes in the cervix associated with ascending infection in pregnant mares. To better characterize morphological and molecular changes in the cervix during placentitis, we examined full thickness histology and mRNA expression for a number of inflammatory and endocrine factors in the mucosa and stroma of the cervix of mares (n = 5) after experimental induction of placentitis via transc...
Coding RNA Sequencing of Equine Endometrium during Maternal Recognition of Pregnancy. Equine maternal recognition of pregnancy (MRP) is a process whose signal remains unknown. During MRP the conceptus and endometrium communicate to attenuate prostaglandin F (PGF) secretion, sparing the corpus luteum and maintaining progesterone production. Recognition of a mobile conceptus by the endometrium is critical by days 14-16 post-ovulation (PO), when endometrium produces PGF, initiating luteolysis. The objective of this study was to evaluate endometrial gene expression changes based upon pregnancy status via RNA sequencing. This experiment utilized a cross-over design with each mare se...
Assessment of peripheral markers and ultrasonographic parameters in pregnant mares receiving intramuscular or intrauterine cloprostenol. The present study aimed to compare two methods of prostaglandin-induced abortion in mares by determining blood markers (progesterone, estradiol-17β, alpha-fetoprotein, 13,14-dihydro-15-keto-prostaglandin-F2α (PGFM)), B-mode ultrasonographic parameters, and time until loss of fetal heartbeat. It was hypothesized that intrauterine infusion of cloprostenol results in earlier fetal compromise than intramuscular administration. Ovarian structures (number and sizes of follicles and corpora lutea area), fetal heartbeat, and fetal mobility of thirteen singleton pregnancies were assessed daily by tra...
Plasma concentrations of steroid precursors, steroids, neuroactive steroids, and neurosteroids in healthy neonatal foals from birth to 7 days of age. Transient hypothalamic-pituitary-adrenal axis dysfunction occurs in critically ill foals with sepsis and neonatal maladjustment syndrome (NMS). Cortisol is the most commonly measured steroid. However, a complex interaction of various steroid compounds might play a role in pathophysiology of this disorder. Objective: To identify steroid compounds present at high concentrations at birth that rapidly and steadily decrease within the first 7 days of life in healthy foals and that might be supportive diagnosis of NMS and other neonatal disorders. Methods: Ten healthy neonatal Quarter Horse foals ...
