Reproduction in horses encompasses the biological processes and mechanisms involved in the breeding and development of equine offspring. This includes the study of reproductive anatomy, physiology, and endocrinology in both mares and stallions. Key areas of interest include the estrous cycle, ovulation, conception, gestation, and parturition. Researchers also examine factors influencing fertility, reproductive technologies such as artificial insemination and embryo transfer, and management practices that impact reproductive success. This page compiles peer-reviewed research studies and scholarly articles that explore the physiological, genetic, and environmental aspects of equine reproduction.
Browne NS, Scarratt WK, Robertson J.A 10-year-old Andalusian mare was presented for evaluation of weight loss, increasing periods of recumbency, and swelling of the lower limbs. Radiographs revealed severe palisading to solid periosteal new bone formation in numerous locations. Necropsy revealed a metastatic malignant adenocarcinoma of ovarian origin with secondary hypertrophic osteopathy. Une jument d’Andalousie âgée de 10 ans a été présentée pour évaluation à la suite d’une perte de poids, de périodes croissantes de décubitus et d’enflure dans les membres inférieurs. Les radiographies ont révélé des lésio...
Sarkar S, Bailey E, Go YY, Cook RF, Kalbfleisch T, Eberth J, Chelvarajan RL, Shuck KM, Artiushin S, Timoney PJ, Balasuriya UB.Equine arteritis virus (EAV) is the causative agent of equine viral arteritis (EVA), a respiratory, systemic, and reproductive disease of horses and other equid species. Following natural infection, 10-70% of the infected stallions can become persistently infected and continue to shed EAV in their semen for periods ranging from several months to life. Recently, we reported that some stallions possess a subpopulation(s) of CD3+ T lymphocytes that are susceptible to in vitro EAV infection and that this phenotypic trait is associated with long-term carrier status following exposure to the virus. ...
Sandra O, Charpigny G, Galio L, Hue I.In mammalian species, endometrial receptivity is driven by maternal factors independently of embryo signals. When pregnancy initiates, paracrine secretions of the preattachment embryo are essential both for maternal recognition and endometrium preparation for implantation and for coordinating development of embryonic and extraembryonic tissues of the conceptus. This review mainly focuses on domestic large animal species. We first illustrate the major steps of preattachment embryo development, including elongation in bovine, ovine, porcine, and equine species. We next highlight conceptus secret...
Sevane N, Dunner S, Boado A, Cañon J.The Spanish Purebred horses, also known as Andalusian horses, compete to the highest standards in international dressage events. Gait and conformation could be used as early selection criteria to detect young horses with promising dressage ability. Although the genetic background of equine size variation has been recently uncovered, the genetic basis of horse conformational and locomotive traits is not known, hampered by the complex genetic architecture underlying quantitative traits and the lack of phenotypic data. The aim of this study was to validate the loci associated with size in 144 Spa...
Dorado J, Anaya G, Bugno-Poniewierska M, Molina A, Mendez-Sanchez A, Ortiz I, Moreno-Millán M, Hidalgo M, Peral García P, Demyda-Peyrás S.Chromosomal abnormalities are one of the main causes of genetic infertility in horses. Currently, their detection rate is rising due to the use of new diagnostic tools employing molecular markers linked to the sex chromosome pair. Despite genetic similarities, there are no previous reports of sterility associated with chromosomal abnormalities in the domestic donkey (Equus asinus). Hereby, we determined the presence of a chromosomal mosaicism in a female donkey with reproductive problems using molecular methodologies developed for horses. A two-and-a-half-year-old jenny characterized by morpho...
Piccinno M, Rizzo A, Cariello G, Sciorsci RL.In this study, the Authors investigated the modulatory effect of three single doses (10, 10, and 10 M) of neostigmine on the spontaneous contractility of equine pre-ovulatory follicles in an isolated organ bath, to establish the relationship between this acetylcholinesterase inhibitor and ovulation, in the mare. The results indicate that neostigmine increases pre-ovulatory contractility in equine follicles at each dose, but in a different manner. Indeed, the rise in contractility induced by neostigmine at 10 M and 10 M was phasic, while at 10 M it was tonic. The data obtained indicate poss...
Khan FA, Chenier TS, Murrant CL, Foster RA, Hewson J, Scholtz EL.Nitric oxide (NO) may have a role in persistent breeding-induced endometritis in mares through an inhibitory effect on uterine contractility. The objectives of this study were to test the effect of NO on spontaneous uterine contractility in-vitro and to evaluate whether this effect varied between the longitudinal and circular muscle layers of the uterus. Reproductive tracts were collected from eight euthanized non-pregnant mares (age 4-19 years; body weight 405-530 kg). Transrectal examination of the reproductive tract was performed before euthanasia to evaluate stage of the estrous cycle and...
Brito LF, Baldrighi JM, Wolf CA, Ginther OJ.The objective of the present study was to investigate the effect of reproductive hormones (GnRH, hCG, LH and progesterone) on the regulation of corpus luteum (CL) and ovarian blood flow. Diestrous mares received a single treatment of saline, 100μg gonadorelin (GnRH), or 1500IU hCG 10days after ovulation. Plasma LH and progesterone concentrations, resistance index (RI) for ovarian artery blood-flow, and percentage of corpus luteum (CL) with color-Doppler signals of blood flow were determined immediately before treatment (hour 0) and at hours 0.25, 0.5, 1, 1.5, 2, 3, 4, 5, and 6. In the GnRH gr...
de Oliveira RA, Scarlet D, Ille N, Aurich C.A decrease in fertility of equine semen during cooled-storage so far has mainly been attributed to changes in sperm membrane function. In the present study we hypothesized that cooled-storage also changes the sperm DNA methylation level. For this purpose, semen was collected from 10 fertile stallions and processed for cooled-storage at 5 °C. Two final concentrations, 50 × 106 and 100 × 106 cells/mL, were used. Semen was analyzed for total motility, progressive motility, membrane integrity, phosphatidylserine translocation (PST), mitochondrial membrane potential and chromatin condensat...
Loux SC, Scoggin KE, Troedsson MH, Squires EL, Ball BA.The cervical mucus plug (CMP) is believed to play an integral role in the maintenance of pregnancy in the mare, primarily by inhibiting microbial entry. Unfortunately, very little is known about its composition or origin. To determine the proteomic composition of the CMP, we collected CMPs from mares (n = 4) at 9 months of gestation, and proteins were subsequently analyzed by nano-LC-MS/MS. Results were searched against EquCab2.0, and proteomic pathways were predicted by Ingenuity Pathway Analysis. Histologic sections of the CMP were stained with H&E and PAS. To identify the origin of ...
Giaretta E, Munerato M, Yeste M, Galeati G, Spinaci M, Tamanini C, Mari G, Bucci D.Setting an open-access computer assisted sperm analysis (CASA) may benefit the evaluation of motility in mammalian sperm, especially when economic constraints do not allow the use of a commercial system. There have been successful attempts to develop such a device in Zebra fish sperm and the system has been used in very few studies on mammalian spermatozoa. Against this background, the present study aimed at developing an open-access CASA system for mammalian sperm using the horse as a model and based upon the Image J software previously established for Zebra fish sperm. Along with determining...
Polasek TCM, Kozicki LE, Pedrosa VB, Weiss RR, Bertol MAF, Camargo CE, Talini R.This study aimed to correlate the inflammatory reaction (IR) caused by a progesterone-releasing intravaginal device (P4) with ovarian activity and pregnancy rate (PR) in embryo-recipient anestrus mares (to decrease the spring transitional period). 50 animals were assigned to three groups: GP4 (P4 group; n = 16), GP4OH (P4 + oxytetracycline hydrochloride and hydrocortisone sprayed onto the device; n = 14), and GNP4 (no intravaginal P4; n = 20). The administration protocol for GP4 was: Day 0, 750 mg P4 + ovarian examination by ultrasonography (US) + vaginal sample collection; Day 8, US;...
de Amorim MD, Chenier T, Nairn D, Green J, Manning S, Card C.CASE DESCRIPTION 5 mares were evaluated because of reproductive complications following long-term (> 1 year) use of intrauterine glass marbles for estrus suppression. CLINICAL FINDINGS 3 mares had 1 intrauterine glass marble, and 2 mares had 2 intrauterine glass marbles. On examination, 2 mares had signs of chronic endometritis, and 3 had signs of pyometra. Marbles or glass shards adhered to the endometrium were identified by means of hysteroscopy in 3 of 5 mares. Five of 7 marbles had surface imperfections or were broken. TREATMENT AND OUTCOME All patients were treated with uterine lavage and...
Marth CD, Firestone SM, Glenton LY, Browning GF, Young ND, Krekeler N.Infectious endometritis is a major cause of reduced pregnancy rates in horses. The objectives of this study were to establish a timeline of the innate immune response in the uterus of healthy horses and to investigate the oestrous cycle effect on this. Endometrial biopsies were collected from five horses before and at 3, 12, 24, 48 and 72 h after inoculation of Escherichia coli, once in oestrus and once in dioestrus. They were analysed by quantitative real-time PCR, microbiology and histology. Neutrophil numbers increased from very low levels in the absence of inflammation to severe neutrophi...
Love CC.Stallion semen evaluation is an important part of the breeding soundness evaluation. The results of the semen evaluation cannot be interpreted without a thorough knowledge of the mare and management effects that may have played a role or may affect the potential fertility of the stallion evaluated. There are considerations and limitations that the clinician should understand about each test. Any sperm quality test must be interpreted with a clear understanding of how it relates to fertility.
Ferris RA.Infectious endometritis is among the leading causes of subfertility in the mare. However, the best way to reliably diagnose these cases of infectious endometritis can be confusing to the veterinary practitioner. The goal of this article is to describe how to perform various sample collection techniques, what analyses can be performed on these samples, and how to interpret the results of these analysis. Additionally, future technologies will be presented that are not currently used in equine reproduction practice.
McCue PM.A wide variety of hormone therapies are used in clinical practice in the reproductive management of horses. The goal of this article is to review therapeutic options for a variety of clinical indications.
Canisso IF, Stewart J, Coutinho da Silva MA.Endometritis was rated as the third most common medical problem encountered in adult horses in North America. It is the leading cause of subfertility in broodmares and is a major contributor to economic loss in the horse breeding industry, with pregnancy rates reported to be as low as 21% in mares with severe endometritis. Endometritis may be categorized as: endometrosis (chronic degenerative endometritis), acute, chronic, active, dormant, subclinical, clinical, and persistent post-breeding. These classifications are not mutually exclusive, and mares may change categories within breeding seaso...
Davila MP, Muñoz PM, Bolaños JM, Stout TA, Gadella BM, Tapia JA, da Silva CB, Ferrusola CO, Peña FJ.To investigate the hypothesis that oxidative phosphorylation is a major source of ATP to fuel stallion sperm motility, oxidative phosphorylation was suppressed using the mitochondrial uncouplers CCCP and 2,4,-dinitrophenol (DNP) and by inhibiting mitochondrial respiration at complex IV using sodium cyanide or at the level of ATP synthase using oligomycin-A. As mitochondrial dysfunction may also lead to oxidative stress, production of reactive oxygen species was monitored simultaneously. All inhibitors reduced ATP content, but oligomycin-A did so most profoundly. Oligomycin-A and CCCP also sign...
Lee G, Jung H, Yoon M.The molecular markers for specific germ cell stages can be utilized for identifying, monitoring, and separating a particular stage of germ cells. The RNA-binding protein Lin28 is expressed in gonocytes of human fetal testes. The Lin28 expression is restricted to a very small population of spermatogonial cells in human, mice, and monkey. The main objective of this study was to investigate the expression pattern of Lin28 in stallion testes at different reproductive stages. Based on the presence or absence of full spermatogenesis and lumina in seminiferous tubules, the testicular samples were cat...
Scarlet D, Ille N, Ertl R, Alves BG, Gastal GDA, Paiva SO, Gastal MO, Gastal EL, Aurich C.The objective of this study was to determine whether (1) systemic and intrafollicular cortisol concentrations in horses are directly related and (2) supraphysiological levels of glucocorticoids affect in vitro maturation (IVM) rates of oocytes. Specifically, we studied the (1) changes in the intrafollicular cortisol and progesterone in context with granulosa cell gene expression during maturation of equine follicles (from 5-9 mm, 10-14 mm, 15-19 mm, 20-24 mm, and ≥25 mm in diameter) and (2) effects of cortisol supplementation on IVM rates and gene expression of equine cumulus-oocyte comple...
Klohonatz KM, Cameron AD, Hergenreder JR, da Silveira JC, Belk AD, Veeramachaneni DN, Bouma GJ, Bruemmer JE.During early pregnancy, the conceptus and mare communicate to establish pregnancy. Cell-secreted vesicles (e.g., exosomes) have been reported in serum. Exosomes contain bioactive materials, such as miRNA, that can mediate cell responses. We hypothesized that a) exosomes are present in mare circulation and quantity varies with pregnancy status, b) exosomes contain miRNAs unique to pregnancy status, and c) miRNAs target pathways in endometrium based upon pregnancy status of the mare. First, serum samples were obtained from mares in a crossover design, with each mare providing samples from a preg...
Brosnahan MM, Silvela EJ, Crumb J, Miller DC, Erb HN, Antczak DF.Invasive trophoblast from Day 34 horse conceptuses survives in extrauterine sites in allogeneic recipients that are immunologically naive to donor major histocompatibility complex class I antigens. The ectopic trophoblast retains its in utero characteristics, including similar lifespan, physiologic effect of its secreted product (equine chorionic gonadotropin) upon the recipient's ovaries, and induction of host immune responses. Immunologic memory has not been considered previously in this experimental system. We hypothesized that primary exposure to ectopic trophoblast would affect the recipi...
Gottschalk M, Sieme H, Martinsson G, Distl O.A high quality of stallion semen is of particular importance for maximum reproductive efficiency. In the present study, we estimated the relationships among estimated breeding values (EBVs) of semen traits and EBVs for the paternal component of the pregnancy rate per estrus cycle (EBV-PAT) for 100 German Warmblood stallions using correlation and general linear model analyses. The most highly correlated sperm quality trait was total number of progressively motile sperm (r = 0.36). EBV-PAT was considered in three classes with stallions 1 SD below (<80), around (80-120), and above (>120) the popu...
Librado P, Fages A, Gaunitz C, Leonardi M, Wagner S, Khan N, Hanghøj K, Alquraishi SA, Alfarhan AH, Al-Rasheid KA, Der Sarkissian C, Schubert M....The horse was domesticated only 5.5 KYA, thousands of years after dogs, cattle, pigs, sheep, and goats. The horse nonetheless represents the domestic animal that most impacted human history; providing us with rapid transportation, which has considerably changed the speed and magnitude of the circulation of goods and people, as well as their cultures and diseases. By revolutionizing warfare and agriculture, horses also deeply influenced the politico-economic trajectory of human societies. Reciprocally, human activities have circled back on the recent evolution of the horse, by creating hundreds...
Olivera R, Moro LN, Jordan R, Luzzani C, Miriuka S, Radrizzani M, Donadeu FX, Vichera G.The demand for equine cloning as a tool to preserve high genetic value is growing worldwide; however, nuclear transfer efficiency is still very low. To address this issue, we first evaluated the effects of time from cell fusion to activation (<1h, n = 1261; 1-2h, n = 1773; 2-3h, n = 1647) on in vitro and in vivo development of equine embryos generated by cloning. Then, we evaluated the effects of using different nuclear donor cell types in two successive experiments: I) induced pluripotent stem cells (iPSCs) vs. adult fibroblasts (AF) fused to ooplasts injected with the pluripotency-inducin...
Proft A, Spiesschaert B, Izume S, Taferner S, Lehmann MJ, Azab W.The serine-threonine protein kinase encoded by gene (pUS3) of alphaherpesviruses was shown to modulate actin reorganization, cell-to-cell spread, and virus egress in a number of virus species. However, the role of the US3 orthologues of equine herpesvirus type 1 and 4 (EHV-1 and EHV-4) has not yet been studied. Here, we show that is not essential for virus replication in vitro. However, growth rates and plaque diameters of a -deleted EHV-1 and a mutant in which the catalytic active site was destroyed were significantly reduced when compared with parental and revertant viruses or a virus in w...
Gallacher K, Santos LC, Campoy L, Bezuidenhout AJ, Gilbert RO.The aim of this study was to develop and evaluate a procedure for equine pudendal nerve block using a peripheral nerve locator. In the first experiment, six ponies were used to determine the relationship between elicited muscle contractions (anal, perineal or both) and nerves serving the perineal region (pudendal, caudorectal and perineal nerves) when methylene blue dye was injected using the electrolocation technique. This experiment showed that the pudendal nerve was approached effectively when both anal and perineal twitch were elicited during electrolocation. In a second experiment, seven ...
Squires EL.Most equine embryos are collected from the donor mare and transferred immediately as fresh embryos or shipped cooled to a recipient station for transfer within 24 hours. Very few equine embryos are frozen despite the numerous advantages of embryo cryopreservation. There are 2 major hurdles: Only the small embryos (<300 μm) provide good pregnancy rates after freezing/thawing and transfer. Also there is no good procedure for superovulating mares; thus, extra embryos for freezing are not readily available. Using either a slow cool or a vitrification method, pregnancy rates of small equine e...
Kareskoski AM, del Alamo MM, Güvenc K, Reilas T, Calvete JJ, Rodriguez-Martinez H, Andersson M, Katila T.Seminal plasma (SP) contains several types of compounds derived from the epididymides and accessory glands. The aim of this study was to examine the protein composition of different ejaculate fractions. Trial I: fractionated ejaculates were collected from two normal and two subfertile stallions. Samples containing pre-sperm fluid and the first sperm-rich jets (HIGH-1), the main sperm-rich portion (HIGH-2), the jets with low sperm concentrations (LOW), and a combined whole-ejaculate (WE) sample was centrifuged, and the SP was filtered and frozen. A part of each SP sample was stored (5°C, 24 h)...
Brown KA, Boerboom D, Bouchard N, Doré M, Lussier JG, Sirois J.Aldo-keto reductases (AKRs) are multifunctional enzymes capable of acting on a wide variety of substrates, including sex steroids. AKRs having 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD) activity can reduce progesterone to 20alpha-hydroxy-4-pregnen-3-one (20alpha-DHP), a metabolite with lower affinity for the progesterone receptor. The objective of this study was to investigate the regulation of equine AKR1C23 during human chorionic gonadotropin (hCG)-induced ovulation/luteinization. The equine AKR1C23 cDNA was cloned and shown to encode a 322 amino acid protein that is conserved (71-81...
Turner RM, McDonnell SM, Feit EM, Grogan EH, Foglia R.Ultrasonographic fetal eye measures have been used to estimate gestational age of the fetus in light horse mares. However, fetal eye measures have not been published for smaller pony breeds. This study was conducted to develop reference ranges for ultrasonographic measures of fetal eyes in small ponies for the purpose of predicting days before parturition (DBP) when breeding or ovulation dates are unknown. Twenty-three Shetland-type pony mares were studied across one (n = 10) or two (n = 13) gestations in 2004 (18 pregnancies) and 2005 (18 pregnancies). Measurements of fetal eyes were obtained...
Freeman DE, Hungerford LL, Schaeffer D, Lock TF, Sertich PL, Baker GJ, Vaala WE, Johnston JK.Data from 116 mares that had caesarean section or vaginal delivery at 2 university hospitals were analysed in 5 groups, as follows: dystocia corrected by caesarean section, Group DCS (n = 48); elective caesarean section, Group ECS (n = 10); caesarean section concurrently with colic surgery, Group CCS (n = 8); assisted vaginal delivery, Group AVD (n = 22); and controlled vaginal delivery under general anaesthesia, Group CVD (n = 28). Survival rate in all mares that had caesarean section, excluding Group CCS, was 88% (51/58). All mares in Group ECS survived and Group CCS had the lowest survival ...
Li X, Tremoleda JL, Allen WR.The effects of repeated passage in vitro of fetal fibroblast cells (FFC) and adult fibroblast cells (AFC) on nuclear remodelling and first embryonic division when used to reconstruct horse oocytes, and the reasons for the developmental block in progression to the two-cell stage were investigated. A total of 463 metaphase II oocytes produced 427 fibroblast-cytoplasm couplets after nuclear transfer, which finally resulted in 319 reconstructed oocytes. With increasing numbers of passages, the rates of nuclear remodelling decreased in both types of donor cell; about half of the fused donor cell nu...
The protein journalJanuary 18, 2023
Volume 42, Issue 1 24-36 doi: 10.1007/s10930-023-10092-x
Rodríguez MC, Mussio PE, Villarraza J, Tardivo MB, Antuña S, Fontana D, Ceaglio N, Prieto C.Equine chorionic gonadotropin (eCG) is a glycoprotein hormone widely used in timed artificial ovulation (TAI) and superovulation protocols to improve the reproductive performance in livestock. Until recently, the only eCG products available in the market for veterinary use consisted in partially purified preparations of pregnant mare serum gonadotropin (PMSG). Here, a bioactive recombinant eCG (reCG) produced in suspension CHO-K1 cells was purified employing different chromatographic methods (hydrophobic interaction chromatography and reverse-phase (RP)-HPLC) and compared with a RP-HPLC-purifi...
Tait AD, Hodge LC, Allen WR.The production of equilin and the other ring B-unsaturated estrogens by the pregnant mare is anomalous in that they are biosynthesised by a cholesterol-independent pathway. Fetal horse gonads were incubated with tritiated sodium acetate and radiochemically pure 3 beta-hydroxy-5,7-pregnadien-20-one and 3 beta-hydroxy-5,7-androstadien-17-one were isolated. A fetal gonad--placental system is proposed for equilin production, 3 beta-hydroxy-5,7-pregnadien-20-one being a precursor for 3 beta-hydroxy-5,7-androstadien-17-one in the fetal gonad and the latter being the precursor of equilin in the place...
Thway TM, Clay CM, Maher JK, Reed DK, McDowell KJ, Antczak DF, Eckert RL, Nilson JH, Wolfe MW.Immortalized cell lines have many potential experimental applications including the analysis of molecular mechanisms underlying cell-specific gene expression. We have utilized a recombinant retrovirus encoding the simian virus-40 (SV-40) large T antigen to construct several immortalized cell lines of equine chorionic girdle cell lineage - the progenitor cells that differentiate into the equine chorionic gonadotropin (eCG) producing endometrial cups. Morphologically, the immortalized cell lines appear similar to normal chorionic girdle cells. Derivation of the immortalized cell lines from a cho...
Setchell BP, Cox JE.In 3 testes of 2 adult Pony stallions under halothane anaesthesia, catheters were inserted into a vein and a lymphatic vessel in the spermatic cord and into a vein on the surface of the testis. Lymph and venous blood were collected from the catheters in the cord and p-aminohippurate (2% w/v, 0 . 1 ml/min) was infused into the vein on the testis to determine blood flow by dilution. After 1 h, 6000 i.u. hCG was injected i.v. and collections continued for 45 min. The testes weighed 126-176 g. Lymph flow was 20-150 microliter/min before hCG and 100-270 microliter/min after hCG; the range of blood ...
Dell'Aquila ME, Cho YS, Minoia P, Traina V, Fusco S, Lacalandra GM, Maritato F.Conventional IVF as well as several assisted microfertilization techniques have shown limited success in the horse. After recent positive results achieved with intracytoplasmic injection of a single spermatozoon (ICSI) in human IVF, we chose to try the method in the horse. We compared conventional IVF to ICSI by fertilization rates of oocytes with compact and expanded cumuli and by developmental potential of the resulting embryos. Cumulus-oocyte complexes (COCs) were obtained by aspirating the follicular fluid from the ovaries of slaughtered mares. Complexes showing complete cumulus investment...
Vasilieva NA, Tchabovsky AV.Fitness consequences of early-life conditions remain unclear and poorly studied in mammals. Based on long-term observations of yellow ground squirrels (Spermophilus fulvus), we identified early determinants of female fitness by analyzing the effects of early-life individual and environmental characteristics (weaning weight, weight gain rate, date of natal emergence, natal litter size, location of the natal burrow, local density of juveniles, population density and precipitation in the post-weaning period) on lifetime reproductive success (LRS). We found high variation and right-skewed distribu...
Johnson L.Seasonal variation in number of spermatogonia and germ cell degeneration was evaluated to determine which mechanism might explain seasonal differences in daily sperm production per testis (DSP/testis) or per g parenchyma (DSP/g) in stallions. Comparing 28 adult stallions (4 to 20 yr old) in each of the nonbreeding (December-January) and breeding (June-July) seasons, the population of type A spermatogonia was more than two times greater (P less than 0.01) in the breeding season. While the number of type B spermatogonia also was elevated (P less than 0.01) in the breeding season, the number of t...
Hamed MA, Amin YA, Mohamed RH, El-Adl M, Bazeed SM, Elnegiry AA, Shawki HH, Al-Lethie AA.Chemical castration of male animals is an alternative to surgical castration for inducing azoospermia, consequent sterility. Intra-testicular injection of zinc gluconate has been used for chemical castration in several animal species. However, its application to equine species, such as donkeys, has yet to be reported. This study aimed to evaluate the use of zinc gluconate for the chemical castration of male donkeys and to compare its effectiveness relative to routine surgical castration. For this purpose, investigations of serum testosterone and anti-Müllerian hormone levels, testicular ultra...
Brown-Douglas CG, Firth EC, Parkinson TJ, Fennessy PF.There is little information on age, weight and time of year of puberty in Thoroughbred horses, and the interpretation of such data is difficult due to the wide variety of descriptions of the onset of puberty. Objective: To examine the age, bodyweight and date of onset of puberty in Thoroughbreds born in spring and autumn. Methods: Bodyweight data and blood samples were collected in 59 pasture-raised Thoroughbred horses. Five autumn-born and 18 spring-born colts and 3 autumn-born and 33 spring-born fillies were examined from birth to age 13 and 17 months. A testosterone concentration >2 s.d. ab...
Dell'aquila ME, Fusco S, Lacalandra GM, Maritato F.The aim of this study was to develope an efficient and reproducible procedure for in vitro maturation (IVM) and fertilization (IVF) in the horse. Cumulus-oocyte complexes (COCs) recovered from the ovaries of mares slaughtered during the breeding season were morphologically evaluated, and those showing a compact cumulus and homogeneously appearing cytoplasm were selected for culture. Effects on the maturation of estrous mare serum (EMS) versus estrous cow serum (ECS) as medium supplement were also evaluated (Experiment 1). In Experiment 2, the fertilization of in vitro matured oocytes with froz...
Stout TA.Situations in which suppression or stimulation of reproductive activity in stallions has been attempted, or is desired, include resolution of the equine arteritis virus 'shedding' state, induction of testicular descent in inguinal cryptorchids, and the improvement of sperm production capacity and/or semen quality in sub-fertile stallions. However, the most common reason for wanting to modulate reproductive activity in a stallion is to alter the expression of sexual behaviour. In the case of intact stallions used for competitive or recreational purposes, the overt expression of sexual or aggres...
Herrera-Luna CV, Budik S, Aurich C.Glucocorticoids (GCs) are important mediators of the stress response and have been implicated in the function and regulation of testicular functions in different species. In many tissues, intracellular glucocorticoid activity is controlled by either or both of the two known isoforms of 11β-hydroxysteroid dehydrogenase (11βHSD) type 1 and 2, which interconvert active and inactive GCs. Little is known about the effects of stress on fertility in the equine species. The main objective of the present study was to investigate the expression of receptors for GCs and adrenocorticotropic hormone [ACT...
Gastal GD, Alves BG, Alves KA, Souza ME, Vieira AD, Varela AS, Figueiredo JR, Feugang JM, Lucia T, Gastal EL.The method of transportation and the conditions imposed on the ovarian tissue are pivotal aspects for the success of ovarian tissue cryopreservation (OTC). The aim of this study was to evaluate the effect of the size of the ovarian tissue (e.g. whole ovary, biopsy size and transplant size) during different times of storage (0, 6, 12 and 24 h) on the structural integrity of equine ovarian tissue transported at 4°C. Eighteen pairs of ovaries from young mares (<10 years old) were harvested in a slaughterhouse and processed to simulate the fragment sizes (biopsy and transplant size groups) o...
Han H, Dong H, Chen Q, Gao Y, Li J, Li W, Dang R, Lei C.Testes produce sperm, and investigations into gene expression in the testes will enhance the understanding of the roles of testicular genes in male reproduction. Cryptorchidism, the failure of one or both testes to descend into the scrotal sac, is a common congenital malformation in horses. The major clinical consequence of this abnormality is impaired fertility. The aim of this study was to analyze the expression patterns of testicular genes and to identify the differentially expressed genes (DEGs) in testes between cryptorchid and normal horses. In this study, the gene expression patterns in...
Demyda-Peyrás S, Bottrel M, Acha D, Ortiz I, Hidalgo M, Carrasco JJ, Gómez-Arrones V, Gósalvez J, Dorado J.The aim of this study was to evaluate the effect of different cooling rates on post-thaw quality of cryopreserved donkey spermatozoa. Eighteen ejaculates from six adult Andalusian donkeys (three ejaculates per donkey) were collected using an artificial vagina. Pooled semen samples (two ejaculates per pool) were divided into three aliquots, and frozen in Gent freezing extender using three different cryopreservation protocols (P): P1 (conventional slow freezing, as control): semen pre-cooled in an Equitainer for 2 h and frozen in liquid nitrogen (LN) vapour; P2 (controlled pre-freeze cooling r...
Choi YH, Hinrichs K.There is a clinical demand for cryopreservation of both in vivo-recovered and in vitro-produced (IVP) equine embryos. We previously reported successful vitrification of expanded equine blastocysts in fine-diameter microloader pipette tips (MPTs) after blastocoel collapse, in a research setting. Here, we report the results of clinical application of the MPT vitrification technique for both in vivo-recovered and IVP blastocysts. In vivo-recovered blastocysts were obtained by referring veterinarians on Days 6 to 8 after ovulation, and shipped 1 to 10 hours to the laboratory before vitrificat...
Guerin MV, Deed JR, Kennaway DJ, Matthews CD.Plasma melatonin was measured at the winter and summer solstices and the autumn and spring equinoxes in four mares held under natural conditions at 35 degrees S. At all seasons the onset of the nightly elevated melatonin was coincident with or after the time of sunset and the melatonin offset after the time of sunrise. The duration of elevated melatonin was not different from the duration of natural scotophase for each season, with the duration of elevated melatonin longer in winter than the other seasons. Immediately following each 24 hr sampling two mares were resampled in acutely extended d...
Leemans B, Gadella BM, Stout TA, Nelis H, Hoogewijs M, Van Soom A.Induction of hyperactivated motility is considered essential for triggering the release of oviduct-bound mammalian spermatozoa in preparation for fertilization. In this study, oviduct-bound stallion spermatozoa were exposed for 2 h to: i) pre-ovulatory and ii) post-ovulatory oviductal fluid; iii) 100% and iv) 10% follicular fluid (FF); v) cumulus cells, vi) mature equine oocytes, vii) capacitating and viii) non-capacitating medium. None of these triggered sperm release or hyperactivated motility. Interestingly, native FF was detrimental to sperm viability, an effect that was negated by heat in...
Vissani MA, Damiani AM, Barrandeguy ME.Equine coital exanthema (ECE) is a highly contagious, venereally-transmitted mucocutaneous disease, characterized by the formation of papules, vesicles, pustules and ulcers on the external genital organs of mares and stallions, and caused by (EHV-3). The infection is endemic worldwide and the virus is transmitted mainly through direct contact during sexual intercourse and by contaminated instruments during reproductive maneuvers in breeding facilities. The disease does not result in systemic illness, infertility or abortion, yet it does have a negative impact on the equine industry as it forc...
Tryon RC, White SD, Famula TR, Schultheiss PC, Hamar DW, Bannasch DL.To assess heritability and mode of inheritance for hereditary equine regional dermal asthenia (HERDA) in Quarter Horses. Methods: 1,295 horses with Quarter Horse bloodlines, including 58 horses affected with HERDA. Methods: Horses were classified as affected or unaffected or as undetermined when data were insufficient to assess phenotype. Pedigree data were analyzed to determine the probable mode of inheritance. Heritability was estimated by use of Bayesian statistical methods. Results: Heritability (mean+/-SD) of HERDA was estimated to be 0.38+/-0.13, with both sexes having an equal probabili...
Kirkpatrick JF, Turner A.Despite a large body of safety data, concern exists that porcine zonae pellucidae (PZP) immunocontraception--used to manage wild horse populations--may cause out-of-season births with resulting foal mortality. Our study at Assateague, Maryland indicated the effects of immunocontraception on season of birth and foal survival between 1990 and 2002 on wild horses from Assateague Island. Among 91 mares never treated, 69 (75.8%) of foals were born in April, May, and June (in season). Among 77 treated mares, 50 (64.9%) were born in season. Of 29 mares foaling within 1 year after treatment (contracep...
Medill SA, Janz DM, McLoughlin PD.Steroid-hormone concentrations from non-invasively obtained biomarkers, like hair, can provide a representation of circulating hormones diffused over relatively long time periods (e.g., weeks or months). The hormone cortisol is often associated with physiological or even psychological stress, while testosterone is strongly associated with male development and reproductive success. Increasingly, studies are using hormone levels derived from hair to make inferences among both domestic animals and wildlife. For horses, all previous hair hormone analysis has been done on companion or working anima...
Cox JE, Edwards GB, Neal PA.The authors analyse data collected over 23 years from 500 cryptorchid horses. They show that left- and right-sided abdominal cases occur with approximately equal frequency in ponies. Approximately half the right-sided unilateral abdominal cases have the epididymal tail descended while only 20 per cent of the left-sided cases do. These findings are briefly discussed. From their analysis of inguinal cryptorchidism the authors conclude that it is a relatively more complex phenomenon with incidence changing with age as well as breed. Right-sided retention predominates in young ponies, probably bei...
Erol E, Jackson C, Horohov D, Locke S, Smith J, Carter C.Determination of fetal serum amyloid A (SAA) concentrations in aborted fetuses can provide valuable information regarding the infectious and/or inflammatory process of abortion in horses. To investigate the relationship between fetal SAA levels and the infectious/inflammatory disease process in feto-placental tissues, a SAA ELISA was used to test heart serum samples of 89 equine fetuses that were necropsied and diagnosed in the following groups: a multiorgan disease process diagnosed with an identified microorganism (14 cases, group 1); only placentitis diagnosed with an identified microorgan...
