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.
Schauer SN, Guillaume D, Decourt C, Watson ED, Briant C, Donadeu FX.There is evidence in several species that high circulating LH concentrations can interfere with normal follicle development and ovulation. In the mare, high LH levels after induction of luteolysis with PGF(2α) have been temporally associated with an increased incidence of anovulatory follicles. We hypothesized that a premature increase in LH levels during a follicular wave in mares would disrupt normal follicle maturation leading to ovulatory dysfunction. In experiment 1, all follicles >10 mm were ablated at midestrous cycle in pony mares followed by twice daily administration of equine LH...
Melkus E, Witte T, Walter I, Heuwieser W, Aurich C.In mares, mating-induced persistent endometritis contributes to low fertility. The condition is in part related to delayed clearance of mucus accumulated within the uterine lumen. The objective of this study was to investigate the endometrial response of healthy mares to intrauterine (i.u.) treatment with N-acetylcysteine (NAC). Oestrous mares (n = 12) were randomly assigned to a treatment (TM) or control (C) group and received an i.u. infusion of 5% NAC and saline (total volume 140 ml), respectively. Endometrial biopsies were collected in five of the mares 24 h after treatment, in the rem...
Hahn S, Giaglis S, Hoesli I, Hasler P.The intention of this review is to provide an overview of the potential role of neutrophil extracellular traps (NETs) in mammalian reproduction. Neutrophil NETs appear to be involved in various stages of the reproductive cycle, starting with fertility and possibly ending with fetal loss. The first suggestion that NETs may play a role in pregnancy-related disorders was in preeclampsia, where vast numbers were detected in the intervillous space of affected placentae. The induction of NETosis involved an auto-inflammatory component, mediated by the increased release of placental micro-debris in p...
Hartig W, Houe H, Andersen PH.The plentiful data on Danish horses are currently neither organized nor easily accessible, impeding register-based epidemiological studies on Danish horses. A common database could be beneficial. In principle, databases can contain a wealth of information, but no single database can serve every purpose. Hence the establishment of a Danish equine health database should be preceded by careful consideration of its purpose and content, and stakeholder attitudes should be investigated. The objectives of the present study were to identify stakeholder attitudes to the importance, purpose, research ar...
Sayasith K, Lussier J, Doré M, Sirois J.Little is known about the expression and regulation of epiregulin (EREG) and amphiregulin (AREG) in ovarian follicles of large monoovulatory animal species. To characterize the gonadotropin-dependent regulation of EREG and AREG mRNAs in equine follicles prior to ovulation, extracts were prepared from equine follicles collected during estrus between 0 and 39h post-hCG and corpora lutea obtained on day 8 of the estrous cycle (day 0=day of ovulation). Results from RT-PCR/Southern blot analyses showed that levels of EREG and AREG mRNAs were very low in follicles obtained at 0h but increased therea...
Binanti D, Livini M, Riccaboni P, Sironi G.A 16-year-old primiparous mare aborted an apparently normal fetus at 240 days of gestation. A large, oval mass, measuring approximately 20 cm × 30 cm × 20 cm, was detected attached to the umbilical cord of the fetus. On the cut surface, the mass showed multifocal cystic structures, foci of mineralization, and diffuse hemorrhages. Histological examination of the mass revealed haphazardly arranged cartilage, bone, mesenchymal stroma, adipose tissue, vascular structures, smooth muscle, ciliated epithelium, squamous cornifying epithelium, and undifferentiated germ cells with areas of necrosis an...
Tachibana Y, Nakano Y, Nagaoka K, Kikuchi M, Nambo Y, Haneda S, Matsui M, Miyake Y, Imakawa K.Despite enormous efforts, biochemical and molecular mechanisms associated with equine reproduction, particularly processes of pregnancy establishment, have not been well characterized. Previously, PCR-selected suppression subtraction hybridization analysis was executed to identify unique molecules functioning in the equine endometrium during periods of pregnancy establishment, and granzyme B (GZMB) cDNA was found in the pregnant endometrial cDNA library. Because GZMB is produced from natural killer (NK) cells, endometrial expression of GZMB and immune-related transcripts were characterized in ...
Vizuete G, Diez E, Galisteo J, Agüera E, Aguilera-Tejero E, Perez-Marín CC.The aim of this study was to evaluate the effects of different treatments for induction and synchronization of oestrus and ovulation in seasonally anovulatory mares. Fifteen mares formed the control group (C), while 26 mares were randomly assigned to three treatment groups. Group T1 (n = 11) were treated with oral altrenogest (0.044 mg/kg; Regumate(®) ) during 11 days. Group T2 (n = 7) was intravaginally treated with 1.38 g of progesterone (CIDR(®) ) for 11 days. In group T3 (n = 8), mares were also treated with CIDR(®) , but only for 8 days. All mares received PGF2α 1 day afte...
Aitken RJ, Gibb Z, Mitchell LA, Lambourne SR, Connaughton HS, De Iuliis GN.The prolonged incubation of human spermatozoa in vitro was found to induce a loss of motility associated with the activation of mitochondrial reactive oxygen species generation in the absence of any change in mitochondrial membrane potential. The increase in mitochondrial free radical production was paralleled by a loss of protein thiols and a concomitant rise in the formation of 4-hydroxynonenal, an electrophilic product of lipid peroxidation that was found to directly suppress sperm movement. These results prompted a search for nucleophiles that could counteract the action of such cytotoxic ...
Rioja E, Cernicchiaro N, Costa MC, Valverde A.This study investigated associations between perioperative factors and probability of death and length of hospitalization of mares with dystocia that survived following general anesthesia. Demographics and perioperative characteristics from 65 mares were reviewed retrospectively and used in a risk factor analysis. Mortality rate was 21.5% during the first 24 h post-anesthesia. The mean ± standard deviation number of days of hospitalization of surviving mares was 6.3 ± 5.4 d. Several factors were found in the univariable analysis to be significantly associated (P < 0.1) with increased probabi...
Palm F, Walter I, Nowotny N, Budik S, Helmreich M, Aurich C.In most mammalian species, progestins have a major function in maintaining pregnancy. In humans, the physiologic initiation of parturition bears similarities with inflammatory processes and anti-inflammatory effects of progestins have been suggested to postpone birth until term. To examine if comparable effects exist in the horse, mares were treated with the synthetic progestin altrenogest from day 280 of gestation until parturition (N = 5) or were left untreated as controls (N = 7). Tissue from the amnion (AMN), allantochorion (AC), and endometrium (EM) was collected at foaling and mRNA expre...
Ginther OJ, Pinaffi FL, Rodriguez MB, Duarte LF, Beg MA.During the luteolytic period in mares, the peak of 65% of pulses of a PGF2α metabolite (PGFM) and the peak of a pulse of PRL have been reported to occur at the same hour. It is unknown whether the synchrony reflects an effect of PGF2α on PRL or vice versa. Controls, a flunixin meglumine (FM)-treated group (to inhibit PGF2α), and a bromocriptine-treated group (to inhibit PRL), were used at 14 days postovulation in June and in September (n = 6 mares/group/mo). Blood samples were collected hourly from just before treatment (Hour 0) to Hour 10. Concentrations of PGFM in the FM group were lower ...
Mata F.Several growth models are commonly used in the biological sciences, to model the follicle growth occurring in the estrous cycle. The aim of this project was to find the model that best fit the follicular size growth data for Lusitano mares. Retrospective data collected from reproduction book records of n=84 mares and n=124 cycles was used to find the series to be fitted to the models. The exponential, Gompertz, logistic, von Bertalanffy, Richards and Weibull models were used, and the most parsimonious and best fit was achieved with the logistic model (r(2)=0.999). The logistic model fits the L...
Guimarães T, Lopes G, Ferreira P, Leal I, Rocha A.Cryopreservation of epididymal spermatozoa is a useful tool to preserve genetic material of valuable stallions after emergency castration or unexpected death. For that, testicles and epididymides are generally sent refrigerated to the laboratory. Collection of epididymal spermatozoa is a simple procedure that reduces the volume of the material to be shipped, and may improve the quality of the chilled epididymal sperm cells. In the present study we compared the characteristics of frozen/thawed epididymal spermatozoa after refrigeration of the epididymis or after direct refrigeration of the exte...
Beckelmann J, Budik S, Helmreich M, Palm F, Walter I, Aurich C.An adjustment of sex ratio of offspring to the conditions present at conception is seen in many mammals including horses. This depends on preferential survival of male embryos under conditions of high energy intake. In several species, growth factors including insulin like growth factor (IGF)-1 have been shown to promote embryonic development by decreasing apoptosis and increasing cell proliferation. We hypothesized that sex-related differences in IGF-1 expression in equine embryos during the phase of maternal recognition of pregnancy might exist and thus contribute to preferential survival of...
Nagao JF, Neves Neto JR, Papa FO, Alvarenga MA, Freitas-Dell'Aqua CP, Dell'Aqua JA.This study aimed to determine whether deslorelin acetate could induce double ovulation in mares. In Experiment 1, eight mares were treated with prostaglandin on Day 8 (D8) after ovulation, then treated with saline or with 100 μg of a controlled-release formulation of deslorelin acetate vehicle intramuscularly (IM) every 12h from D8 after ovulation until at least two follicles reached 33 mm. At this time, ovulation was induced with 2500 IU of hCG. Artificial insemination was performed 24h after induction, and embryos were collected on the eighth day after ovulation was first detected. In Exper...
Vieira LA, Gadea J, García-Vázquez FA, Avilés-López K, Matás C.After injury or death of a valuable male, recovery of epididymal spermatozoa may be the last chance to ensure preservation of its genetic material. The objective of this research was to study the effect of sperm storage, at 4°C up to 96h, in the epididymides obtained from castrated horses and its effect on different functional sperm parameters. Aims were to study the effect of (1) sperm storage on viability and chromatin condensation; (2) pre-incubation of recovered epididymal sperm in the freezing extender, prior cryopreservation, on viability and chromatin condensation; and (3) freezing-tha...
Schulman ML, Kass PH, Becker A, Van der Merwe B.Pregnancy losses include early embryonic death (EED) and later (postimplantation) abortion. Abortions, particularly Equid herpesvirus (EHV-1) abortion epizootics, cause severe economic and production losses. The long-term effects of EHV-1 and other abortions on subsequent reproductive performance in broodmare populations, however, remain undefined. This study described the relationships of EED and abortion with the following reproductive outcomes in Thoroughbred systems: breeding efficiency, month of last breeding, subsequent pregnancy and live foal rates. A prospective cohort study in broodma...
Surma-Kurusiewicz K, Winiarczyk S, Adaszek Ł.The purpose of this study was to conduct a comparative analysis of the ORF5 gene fragment nucleotide sequences and the GP5 protein amino acid sequences formed on this matrix, for the equine arteritis virus (EAV) strains isolated from the semen of infected stallions from Eastern Poland. The study covered 41 stallions whose blood serum tested positive for antigens specific to the EAV. The presence of EAV genetic material was shown in material from 5 horses, in one of which permanent presence of viral RNA was detected over the entire 4-year study period (the material was sampled four times at yea...
Klein C, Troedsson MH, Rutllant J.The expression of 12 different aquaporin subtypes in equine endometrium was examined at the mRNA and protein level. Endometrial samples were obtained during anoestrus, oestrus, 8, and 14 days after ovulation in non-pregnant mares, and 14 days after ovulation in pregnant mares. Quantitative PCR revealed a time-dependent pattern for all aquaporin subtypes examined except for AQP10 and 12. AQP3, 5 and 7 showed highest mRNA abundance 8 days after ovulation, while AQP0 and 2 were most abundant at Day 14 of the cycle in non-pregnant mares. At 14 days of pregnancy, AQP1, 4, 8, 9 and 11 displayed ...
Hendrickson DA.Minimally invasive surgery in the human was first identified in mid 900's. The procedure as is more commonly practiced now was first reported in 1912. There have been many advances and new techniques developed in the past 100 years. Equine laparoscopy, was first reported in the 1970's, and similarly has undergone much transformation in the last 40 years. It is now considered the standard of care in many surgical techniques such as cryptorchidectomy, ovariectomy, nephrosplenic space ablation, standing abdominal exploratory, and many other reproductive surgeries. This manuscript describes the hi...
Adams GP, Ratto MH.Ovulation in mammals involves pulsatile release of GnRH from the hypothalamus into the hypophyseal portal system with subsequent release of LH from the anterior pituitary into systemic circulation. Elevated circulating concentrations of LH induce a cascade of events within the mature follicle, culminating in follicle rupture and evacuation. The broad classification of species as either spontaneous or induced ovulators is based on the type of stimulus responsible for eliciting GnRH release from the hypothalamus. In spontaneously ovulating species (e.g., human, sheep, cattle, horse, pigs), relea...
Collodel G, Rinaldi S, Moretti E, Fontani V, Castagna A, Iacoponi F, Terzuoli G, C뻝u F, Careddu GM, Cossu I, Passino ES.The Radio Electric Asymmetric Conveyer (REAC) has been mostly applied to treat symptoms related to psychological stress. In the study, we demonstrated the effect of REAC-Veterinary Neuro Psycho Physical Optimization (VNPPO) treatment protocol on sperm parameters of subfertile (n=11) and fertile (n=4) stallions. Subfertile stallions showed a reduced sperm concentration, progressive motility and normal morphology compared to fertile stallions. An increase in progressive sperm motility and quality of sperm morphology was found in subfertile stallions after the REAC-VNPPO treatment. The positive e...
Galvão A, Valente L, Skarzynski DJ, Szóstek A, Piotrowska-Tomala K, Rebordão MR, Mateus L, Ferreira-Dias G.Regulation of immune-endocrine interactions in the equine endometrium is not fully understood. The aims of the present study were to: (1) investigate the presence of tumour necrosis factor alpha (TNF), interferon gamma (IFNG), Fas ligand (FASLG) and their receptors in the mare endometrium throughout the oestrous cycle; and (2) assess endometrial secretory function (prostaglandins), angiogenic activity and cell viability in response to TNF, oestradiol (E2), progesterone (P4) and oxytocin (OXT). Transcription of TNF and FASLG mRNA increased during the early and late luteal phase (LP), whereas IF...
Hanada M, Maeda Y, Oikawa MA.The secretions of the equine endometrial glands are essential for the survival, growth, and development of the conceptus in early pregnancy, and endometrial gland density is directly related to successful pregnancy outcome. Endometrial biopsy is routinely used to assess the reproductive potential of broodmares. Some previous studies have shown that equine endometrial glands are uniformly distributed throughout the uterus; however, other work has shown variation of the endometrial architecture between biopsy sites, suggesting that a single biopsy is not representative of the entire endometrium....
Cholleti H, Paidikondala M, Munir M, Hakhverdyan M, Baule C.Equine arteritis virus (EAV) causes a respiratory and reproductive disease in horses, equine viral arteritis. Though cell death in infection with EAV is considered to occur by apoptosis, the underlying molecular mechanism has not been extensively elucidated. We investigated the expression of mRNA of pro-apoptotic and caspase genes during EAV infection in BHK21 cells, a well-established cell type for EAV replication. Using a SYBR Green real-time PCR, mRNA of p53, Bax, caspase 3 and caspase 9 were found up-regulated in a time dependent manner in EAV infected cells. Western blot analysis for casp...
Walsh CM, Prendergast RL, Sheridan JT, Murphy BA.The production of melatonin during night-time hours decodes day length for seasonally breeding animals. The use of artificial light to advance the breeding season in mares is common practice within the equine industry. Four healthy Thoroughbred mares were used to evaluate the minimum intensity of light required to inhibit serum melatonin. Mares were fitted with indwelling jugular catheters and using a crossover design blood samples were collected following 1h exposure to light (barn lighting approximately 200 lux), dark (<0.1 lux), and 3, 10, 50, and 100 lux intensities. The light source wa...
Torres A, Silva JF, Bernardes N, Sales Luís J, Lopes da Costa L.Here is reported a disorder of sex development found in the Portuguese Lusitano horse breed. The complex genital phenotype included mammary glands, abdominal testes without epididymis, connected through oviducts to pelvic hypoplastic uterine horns and fused vulvar labia majora from which protruded ventrally a penis-like structure. This structure was presented in a reversed position, the urethral opening placed dorsally in the glans. However, it was functional both for micturition and erection. The horse exhibited female micturition posture and aggressive male-like behaviour, including flehmen,...
Roberto da Costa RP, Costa AS, Korzekwa AJ, Platek R, Siemieniuch M, Galvão A, Redmer DA, Silva JR, Skarzynski DJ, Ferreira-Dias G.Nitric oxide (NO) plays an important role in prostaglandin secretion and angiogenesis in the reproductive system. In the present study, the roles of the NO donor spermine NONOate and tumour necrosis factor-alpha (TNF; as a positive control) in prostaglandin production and angiogenic activity of equine endometria during the oestrous cycle were evaluated. In addition, the correlation between NO production and the expression of key prostaglandin synthase proteins was determined. The protein expression of prostaglandin F synthase (PGFS) increased in early and mid-luteal stages, whereas that of pro...
Rapacz-Leonard A, Raś A, Całka J, Janowski TE.Fetal membrane retention can be a life-threatening condition and its incidence exceeds 50% in heavy draught mares. Although fetal membrane retention is commonly treated with repeated injections of oxytocin, based on the suggestion that it is caused mainly by secondary atony of the uterus, this treatment sometimes fails. This led us to ask if expression of oxytocin receptors differs in mares that retain fetal membranes due to secondary uterine atony. Objective: To determine whether expression of oxytocin receptors in equine placental tissues differs when heavy draught mares expel fetal membrane...
Kadivar A, Shams Esfandabadi N, Dehghani Nazhvani E, Shirazi A, Ahmadi E.Protamines substitute DNA-binding histones during late spermatogenesis in sperm nucleus. Stallion sperm contains all three variants of these arginine-rich and positively charged nuclear proteins (P1, P2 and P3). Two variants of protamine-2, that is P2 and P3, constitute approximately 15% of the entire protamine content. Also, the ratio of protamine-1 to protamine-2 varies among different mammalian species, and abnormal protamine ratios and protamine content are correlated with male infertility. In this study, changes in protamine mRNA abundance for all three protamines were investigated in sta...
Mari G, Morganti M, Merlo B, Castagnetti C, Parmeggiani F, Govoni N, Galeati G, Tamanini C.Since results with using sulpiride and domperidone are conflicting and since both have not been tested at the same time, the aim of this study was to compare the efficacy of these substances for the induction of ovulation in deep anestrous mares in the same experimental conditions and to determine their fertility after artificial insemination (AI) at the induced estrus. Twenty-six non-pregnant, non-lactating standardbred anestrous mares were randomly assigned to three groups and treated daily for 25 days (from February 3rd to February 28th) with either sulpiride (1mg/kg of body weight im SID, ...
Hemberg E, Lundeheim N, Einarsson S.Changes in the conformation of the vulva predispose the mare to uterine infection. Vulvoplasty for closure of the upper vulvar lips improves fertility. Not all mares are resutured after parturition, but are resutured after mating. No clinical data have hitherto been published on the reproductive outcome in mares that are resutured or not after parturition. The objectives of the present study were to investigate relationships between vulvar status (not Caslick-operated, group A; previously Caslick-operated and/or not resutured after the last parturition, groups B and C respectively) and endomet...
Ghosh S, Carden CF, Juras R, Mendoza MN, Jevit MJ, Castaneda C, Phelps O, Dube J, Kelley DE, Varner DD, Love CC, Raudsepp T.We report 2 novel autosomal translocations in the horse. In Case 1, a breeding stallion with a balanced t(4p;30) had produced normal foals and those with congenital abnormalities. Of his 9 phenotypically normal offspring, 4 had normal karyotypes, 4 had balanced t(4p;30), and 1 carried an unbalanced translocation with tertiary trisomy of 4p. We argue that unbalanced forms of t(4p;30) are more tolerated and result in viable congenital abnormalities, without causing embryonic death like all other known equine autosomal translocations. In Case 2, two stallions produced by somatic cell nuclear tran...
Bruemmert JE, Coy RC, Squires EL, Graham JK.Stallion spermatozoa maintain high fertilizing capacity if cooled to 5 degrees C and inseminated within 24 h. However, if spermatozoa are stored for 48 h, fertilizing capacity declines. Therefore, multiple shipments of semen are often required to inseminate mares that remain in estrus for days. Therefore, experiments were designed to determine if adding antioxidants to stallion spermatozoa stored at 5 degrees C for 48 h could maintain motility and fertilizing ability. In the first experiment stallion spermatozoa were incubated in a skim milk (SM) or a skim milk-egg yolk medium in combination w...
Magistrini M, Chanteloube P, Palmer E.In an attempt to define optimal season and ejaculation frequency for frozen semen, semen was collected from 6 stallions (3 horses and 3 ponies) 3 times per week or every day, alternating every week, for 1 year. The semen was evaluated and frozen. All the samples were thawed at the end of the experiment. At collection, fresh semen evaluations showed that winter (as opposed to spring and summer) was associated with low sexual behaviour, small volumes of spermatozoa and gel, high sperm concentration and lower motility. The high ejaculation frequency yielded a decreased volume, concentration of sp...
Devick IF, Leise BS, McCue PM, Rao S, Hendrickson DA.Determining if ovariectomy will abolish unwanted behaviors can be challenging in mares without ultrasonographic ovarian abnormalities and/or endocrine values not consistent with a granulosa cell tumor. The objective of the study was to identify mares that have a positive improvement in unwanted behaviors after elective standing laparoscopic ovariectomy and to determine if the change is associated with any pre- and post-operative endocrine profiles and/or with ovarian histological findings. During the study period 27 mares underwent a bilateral standing laparoscopic ovariectomy. Pre- and post-o...
Smits K, Govaere J, Hoogewijs M, Piepers S, Van Soom A.Intracytoplasmic sperm injection (ICSI) is the method of choice for the in vitro production (IVP) of equine embryos. However, conventional ICSI has been associated with mechanical damage to the oocyte caused by the deformation of the zona pellucida (ZP) and exposure of the oolemma to negative pressure during injection. Introduction of the less traumatic and more efficient piezo drill-assisted ICSI (PDAI) yielded higher cleavage rates and more consistent results. Nevertheless, PDAI is also associated with disadvantages such as the use of mercury and possible DNA damage. This led us to explore a...
Cuervo-Arango J, Mateu-Sánchez S, Aguilar JJ, Nielsen JM, Etcharren V, Vettorazzi ML, Newcombe JR.The objective of this study was to determine the effect of the interval from induced luteolysis to ovulation on fertility of mares from two different farms. At farm 1, 215 mares were inseminated with frozen/thawed semen during 513 estrous cycles over seven consecutive breeding seasons. Estrus was induced with analogues of PGF2α in 179 cycles. At farm 2, 375 embryo flushings were performed in 65 donor mares inseminated with fresh semen; of which, 327 were performed following artificial insemination after PGF-induced luteolysis. In both farms, the intervals from PGF treatment to ovulation (ITO)...
Kavak A, Lundeheim N, Aidnik M, Einarsson S.Evaluation of testicular measurements and daily sperm output (DSO) yields valuable information for predicting the reproductive capacity of stallions. The present study evaluated testicular measurements (height, length, width and circumference) and DSO of eight Tori and eight Estonian breed stallions. One ejaculate of semen was collected daily for 10 subsequent days from each stallion. The gel-free volume of semen was measured with a graduated glass cylinder and the sperm concentration was assessed with a Chorjajev chamber. The volume of gel-free fraction was multiplied by the sperm concentrati...
Griffin RA, Baker M, Aitken RJ, Swegen A, Gibb Z.Stallions experience lower per-cycle conception rates compared to other livestock species, largely because they are selected for breeding based on athletic prowess and not reproductive fitness. Mares are seasonal breeders, and pregnancies cannot be detected until 10-14 days post cover via transrectal ultrasonography. This means the detection of stallion fertility fluctuations is delayed by at least 2 weeks, which within the short breeding season employed by the thoroughbred horse breeding industry, can prove quite costly. For these reasons, there is increased demand for robust laboratory assay...
Silva ESM, Cuervo-Arango J, de Ruijter-Villani M, Klose K, Oquendo PS, Stout TAE.Field data indicate that a longer period of estrus prior to ovulation correlates positively with fertility. To test the hypothesis that the duration of exposure to estrogens prior to progesterone dominance influences endometrial function, we used anestrous mares to simulate varying durations of estrus (3 groups of 5 mares): long (LE), short (SE), and no estrus (NE), as determined by the duration of estradiol priming prior to progesterone treatment: 7, 2 and 0 days for the LE, SE and NE, respectively. Endometrial biopsies were recovered 4 days after progesterone administration in all groups for...
Caballeros JE, Camacho C, Cazales N, Estradé MJ, Fiala-Rechsteiner S, Jobim MIM, Mattos RC.Rapid endometrial adaptations occur with the embryo entering the uterus to create a receptive uterine environment, which is essential for the conceptus' development. The aim of this study was to demonstrate ultrastructural and histological changes of the endometrium at day 5 after ovulation in cyclic and inseminated mares. Mares were daily examined by transrectal palpation and ultrasonographic examination of the reproductive tract until ovulation was detected. In the first cycle, endometrial biopsies from 10 cyclic mares (Cyclic group) were collected on day 5 post-ovulation. In the second cycl...
Koskinen E, Lindeberg H, Kuntsi H, Katila T.Twenty-four Finnhorse mares were examined by rectal palpation and ultrasonography every 6 h during late oestrus to determine the time of ovulation. Milk and serum samples were collected every 6 h after the detected ovulation for progesterone analysis. The progesterone rises took place within 0-54 h and 0-60 h after ovulation, in milk and serum, respectively. Statistically significant differences (p less than 0.05) in progesterone levels were observed for the first time 12-18 h and 18-24 h after ovulation, in serum and milk, respectively, as compared to progesterone levels 0-6 h after ovulation...
Dart AJ, Hodgson DR, Snyder JR.To review the breed, age, gender, clinical and laboratory findings, treatment and outcome of horses with caecal disease presented to a referral centre. Methods: Retrospective study of 96 cases. Methods: The breed, age, and gender of the study population were compared with the corresponding hospital population for the same period. The means (+/- SD) for clinical and laboratory findings were recorded for each caecal disorder. Treatment was categorised as medical or surgical, and outcome was recorded. Results: Caecal diseases included impaction (40% of total cases), rupture associated with concur...
Panzani D, Zicchino I, Taras A, Marmorini P, Crisci A, Rota A, Camillo F.Artificial photoperiod treatment is currently the best method to hasten the first ovulation of the breeding season in winter anoestrus mares. However, this is not easy to apply in large herds of mares and, to be effective, has to be planned in the northern hemisphere in December at the latest. Pharmacological treatments have been proposed as alternatives: GnRH agonists, progesterone or its synthetic agonist Altrenogest, and dopamino-antagonists, as pherphenazine, domperidone or sulpiride. Dopamino-antagonists protocols, beginning at a given day of the year, gave controversial results in terms ...
York CA, Schulte BA.Maintaining a dominant position in a hierarchy requires energetically expensive aggressive displays and physical exertion. Lab based winner-loser studies, often conducted with individuals from non-social species, have shown that subordinates have higher stress hormone levels than dominant individuals. However, in wild studies on cooperative breeders, displays of aggression used to maintain dominance status are associated with elevated stress hormone levels. The effect of reproductive state on dominance and stress has not been addressed within either of these situations. The purpose of this stu...
Morrell JM, Geraghty RM.A method of removing equine arteritis virus (EAV) from equine semen used for artificial insemination is urgently needed. Recent medical studies suggest that a double semen processing technique of density gradient centrifugation followed by a 'swim-up' can provide virus-free sperm preparations for assisted reproduction. Objective: To investigate the use of the double semen processing technique to obtain virus-free sperm preparations from stallion semen containing EAV. Methods: Aliquots of an ejaculate from an uninfected stallion were spiked with virus and processed by the double processing tech...
Laughlin AM, Welsh TH, Love CC, Varner DD, Parrish AR, Forrest DW, Ing NH.In vitro culture systems are valuable tools for investigating reproductive mechanisms in the testis. Here, we report the use of the precision-cut in vitro system using equine testicular slices. Testes were collected from immature light breed stallions (n=3) and cut into slices (mean slice weight= 13.85 ± 0.20 mg; mean slice thickness=515.00 ± 2.33 μm) using the precision-cut tissue-slicing method. Four tissue slices were placed on a grid floating on medium in individual vials. After a 1-h preincubation, they were exposed to medium containing ovine luteinizing hormone (oLH) at concentrations...
Cuervo-Arango J, Claes AN, Stout TA.The aim of this study was to compare the success of embryo transfer (ET) performed by veterinarians with different degrees of experience using one of two ET techniques. Over three years, 179 embryos were transferred by three operators with moderate to high experience using a 'conventional' manual technique, and 170 embryos were transferred by four operators with little or no previous ET experience using a 'Wilsher' technique (Polansky speculum and Wilsher's cervical forceps). The pregnancy status of recipient mares at the first pregnancy diagnosis and the embryo loss by the last examination we...
Cribb NC, Bouré LP.To describe laparoscopic removal of a large testicular teratoma in a standing horse. Methods: Clinical report. Methods: Thoroughbred horse (11 months) with a testicular teratoma. Methods: A unilateral cryptorchid testicle could not be removed by an inguinal approach under general anesthesia because of it s large size. After recovery from general anesthesia, ultrasound evaluation revealed a 24 x 19 cm fluid-filled testicular mass. The mass was removed by paralumbar fossa laparoscopy with the horse in a standing position. After fluid aspiration of the mass, the mesorchium and ductus deferens wer...
Esteller-Vico A, Liu IK, Vaughan B, Steffey EP, Brosnan RJ.In the uterus of the mare, data obtained using transrectal Doppler ultrasonography indicate that uterine blood flow (UBF) is dynamic and changes throughout the estrous cycle. Degenerative lesions in the uterus are associated with subfertility and infertility. Among these lesions, vascular elastosis has been reported in aged, multiparous, and infertile mares. Angiosis of the uterine vasculature could potentially compromise UBF. The objectives of this experiment are to determine levels of UBF and perfusion of reproductively healthy mares and compare them to levels of subfertile/infertile mares a...
Pozor M, Conley AJ, Roser JF, Nolin M, Zambrano GL, Runyon SP, Kelleman AA, Macpherson ML.Recently, anti-Müllerian hormone (AMH) was validated as a reliable marker of testicular damage caused by various chemotherapy drugs in humans and in mice. In horses, the reference values of AMH concentrations in normal stallions, during different seasons of a year, have been recently reported. However, this hormone was not evaluated in subfertile or infertile stallions with testicular damage. Therefore, the objective of this study was to investigate the effects of experimentally induced testicular degeneration on the concentration of AMH in stallions. Severe but transient testicular degenerat...
Canisso IF, Ball BA, Erol E, Claes A, Scoggin KE, McDowell KJ, Williams NM, Dorton AR, Wolfsdorf KE, Squires EL, Troedsson MH.Nocardioform placentitis in horses is poorly understood, and the development of an experimental model would be of help in understanding the pathogenesis of the disease. Objective: To investigate whether (1) intrauterine inoculation of Crossiela equi during the periovulatory period or (2) i.v., oral or intranasopharyngeal inoculation of C. equi during midgestation would result in nocardioform placentitis, and (3) before and after mating endometrial swabs present evidence of nocardioform placentitis-associated organisms (C. equi or Amycolatopsis spp.). Methods: In Study I, mares (n = 20) rec...
Cox JE, Redhead PH, Dawson FE.The results of performing 1720 blood tests for equine cryptorchidism are described. Using the paired sample human chorionic gonadotrophin (hCG) stimulation test and measuring testosterone, 6.7 per cent of tests did not give a clear result. If only the testosterone concentration in the pre-hCG blood sample was used, this percentage rose to 14 per cent. The paired sample hCG stimulation test was 94.6 per cent accurate. A comparison was made between the paired hCG stimulation test and the measurement of conjugated oestrogen in a single sample. The latter did not give as many doubtfuls but gave fa...
Blach EL, Amann RP, Bowen RA, Frantz D.Better procedures for freezing and thawing equine sperm are needed since variable fertility is obtained when cryopreserved sperm are used. To evaluate current methods of freezing equine sperm, we examined spermatozoal quality by means of two new techniques. These measured the integrity of plasma-acrosomal membranes by immunofluorescent analyses of binding of an antibody specific to the acrosome and evaluated eight parameters of spermatozoal motion using a fully automated computerized system. Five ejaculates from each of eight stallions were processed for freezing in egg yolk-lactose extender w...
Sievert M, Krohn J, Wehrend A.Due to the special structure of the equine placenta, foals depend on an adequate intake of high-quality colostrum post natum in order to ensure the development of passive immunity. The quality of the colostrum is determined, among other things, by the IgG content. This may be evaluated in the colostrum by direct and indirect methods (density and refractive index). The density of the colostrum is measured by a colostrometer and should amount to at least 1060 g/l. Refractometry is suitable for assessing the relative density or refractive index. Good equine colostrum has a Brix value of at leas...
Vagnoni KE, Ginther OJ, Lunn DP.Chorionic girdle cells are a highly invasive subpopulation of trophoblast cells of the equine conceptus. By Day 35 (Day 0 = day of ovulation), cells of the chorionic girdle adhere to the uterine epithelium and begin to invade the endometrial wall. Invasive cells must attach to extracellular matrix proteins, secrete proteinases capable of degrading matrix, and migrate through the degraded matrix; invasion is largely dependent on the proteinase activity of the cells. The objective, therefore, was to develop an in vitro system to examine the mechanisms of equine chorionic girdle cell invasion thr...
