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Topic:Horses
"Horses" is a broad topic that encompasses various aspects of equine biology, behavior, and management. This category includes studies on the anatomy, physiology, and genetics of horses, as well as their behavior, nutrition, and care. Research in this area may also cover the historical and cultural significance of horses, their roles in agriculture, sport, and therapy, and the challenges associated with their conservation and welfare. The page aggregates peer-reviewed research articles and scholarly studies that explore the multifaceted relationships between humans and horses, examining both scientific and socio-economic perspectives.
Functional and histopathological evidence of cardiac parasympathetic dysautonomia in equine grass sickness. The parasympathetic terminal cardiac ganglia were examined in three normal horses and in five horses with grass sickness. Histopathological changes, consistent with those observed in other ganglia of horses with grass sickness, were identified in the terminal cardiac ganglia of the affected horses. A functional analysis of cardiac autonomic control by time domain analysis (TDA) of heart rate variability was applied to eight horses with grass sickness, and double-paired to 16 normal horses on the basis of their age, sex and breed, and the time of day at which the electrocardiographs were obtain...
Uterine contractility is necessary for the clearance of intrauterine fluid but not bacteria after bacterial infusion in the mare. Bacteria were infused into the uteri of 5 estrous mares resistant to persistent mating-induced endometritis, first during a control cycle, and then during treatment with clenbuterol, a beta 2 agonist. Uterine cellular response was evaluated 48 h later by transrectal ultrasonography, followed by uterine lavage. During clenbuterol treatment all mares accumulated intrauterine fluid, whereas in the control cycle none of the mares retained fluid. There was no significant difference between the 2 cycles in the cloudiness of the lavage fluid, number of cells per milliliter, percentage of neutrophils ...
Effect of time during transport of excised mare ovaries on oocyte recovery rate and quality after in vitro maturation. In the mare only a limited number of oocytes can be successfully collected in vivo, so that when large numbers of oocytes are needed for experimentation, ovaries harvested from slaughtered mares must be used. The resulting temperature changes and time intervals mandated by handling and transport of ovaries from the slaughterhouse to the laboratory adversely affect the rate of oocyte recovery and their quality after IVF and maturation. We chose to study the effect of temperature and time in transit of excised ovaries by evaluating rate of oocyte recovery, nuclear maturation stage reached before...
Peripuberal sexual development of Pantaneiro stallions. Pantaneiro horses are a breed native to flood plains of Brazil, where they thrive with little human interference. The aims of this study were to characterize age-associated changes in testicular size, serum testosterone and sexual behavior and to determine age at puberty as well as to evaluate daily sperm production in the Pantaneiro stallion. After weaning the males were kept in bachelor groups away from the females, in a separated area in the natural environment of flood plains. Infantile period ended at approximately 14.4 m.o. of age. Sexual interest and breeding capability first appeared b...
Application of the restricted-access precolumn packing material alkyl-diol silica in a column-switching system for the determination of ketoprofen enantiomers in horse plasma. The group of LiChrospher ADS (alkyl-diol silica) sorbents that make part of a unique family of restricted-access materials, have been developed as special packings for precolumns used in the LC-integrated sample processing of biofluids. The advantage of these sorbents lies in the direct injection of untreated biological fluids, that is without sample clean-up, the elimination of the protein matrix with a quantitative recovery together with an on-column enrichment. The present method is based on previous work applying UV detection at 260 nm for ketoprofen determinations. Plasma samples introduc...
Concentrations of total protein, albumin and immunoglobulins in undiluted uterine fluid of gynecologically healthy mares. Undiluted uterine fluid from 20 Warmblood/Standardbred mares (5 to 14 yr old) was recovered by absorption to an intrauterine tampon. The mares were considered gynecologically healthy based on a clinical examination including uterine swabs for cytology and bacteriology as well as endometrial biopsy examinations. The protein profiles (SDS-PAGE) and concentrations of total protein, albumin, and immunoglobulins (Ig) A and G in the uterine fluid were examined and compared with the same proteins in serum. Major peaks were identified on the obtained protein profiles, and there was a clear similarity ...
Differences in uterine position of reproductively normal mares and those with delayed uterine clearance detected by scintigraphy. The position of the uterus within the abdomen may affect a mare's ability to rapidly clear the uterine lumen of contamination. In this study, the position of the uterus was determined from left and right lateral flank scintigrams taken 1 and 2 h after intrauterine infusion of radiocolloid. Scintigraphy was performed during estrus in 44 mares, 24 were reproductively normal and 20 exhibited a delay in uterine clearance. Reproductively normal mares were nulliparous (n = 14) or pluriparous (n = 10), 3 to 21 yr of age, had no history of persistent uterine infections and cleared > 50% of a radioc...
Uterine clearance and resistance to persistent endometritis in the mare. The objective of this article is to review the role of uterine defense mechanisms in natural resistance to chronic or persistent endometritis. A breakdown of uterine physical clearance mechanisms is currently believed to play a major role in susceptibility to persistent endometritis. Mares with increased susceptibility to persistent endometritis have impaired myometrial contractility in response to an acute inflammation, resulting in an accumulation of fluid and inflammatory products within the uterine lumen. The origin of this defect remains unknown. Recent studies have demonstrated that sper...
Immunolocalization of P450C17 in the mare corpus luteum. Although the mare corpus luteum (CL) is capable of aromatization, the expression of other enzymes involved in estradiol synthesis is not yet clear. This study examined the localization of P450C17 in the mare CL at different stages of its functional development. In ovaries from follicular phase mares P450C17 was localized in the theca cells of ovarian follicles. Following ovulation, no immunostaining for P450C17 was detected in the mature CLs of nonpregnant mares. In pregnant mares, no immunostaining for P450C17 was identified in the corpus luteum prior to secretion of eCG by the feto placental...
The suitability of echotexture characteristics of the follicular wall for identifying the optimal breeding day in mares. Ultrasonically detected changes in the equine preovulatory follicle were characterized for the 3 d preceding ovulation early (n = 47) and late (n = 14) in the ovulatory season. Values for the following follicle end points increased progressively over the 3 d: diameter, incidence of nonspherical shape, echogenicity of the apparent granulosa layer, and prominence of an anechoic layer beneath the granulosa. The latter 2 echotexture end points were scored from 1 to 3 (minimal to maximal). Follicle diameter and the 2 echotexture characteristics were more prominent early than late in the ovulatory s...
Diarrhoea associated with cryptosporidial oocyst shedding in a quarterhorse stallion. Cryptosporidial oocyst shedding was detected in a 2.5-year-old Quarterhorse stallion with diarrhoea. Based on the detection of cryptosporidial oocysts, and the absence of other aetiological agents or enteropathogens, cryptosporidiosis was presumptively diagnosed. This case was unusual because cryptosporidial oocyst shedding is primarily found in some immunocompromised or immature horses, and has not been reported in healthy mature horses.
Effects of density on displacement, falls, injuries, and orientation during horse transportation(1). Three groups of slaughter-type horses, totaling 30 mares and 29 geldings, were used to determine density effects on displacement (distance moved during a stop), falls, injuries, and orientation using a single-deck, open-topped commercial semi-trailer. Each horse was assigned to one of two treatments: high density (1.28 m(2)/horse with 14 horses) or low density (2.23 m(2)/horse with eight horses). Both treatments occurred sequentially on the same day (treatment order was alternated each trial), using the middle 2.44x7.32 m compartment of a large semi-tractor trailer. The horses were transported...
Effect of PGE2 on uterine contractility and tone in mares. A technique for transvaginal, ultrasound-guided intrauterine injection was developed. After preliminary study using different approaches, the procedure was successful in 24 of 25 (96%) mares, based on detecting fluid in the uterine lumen during and after the injection. The technique was used to study the effect of PGE2, reportedly produced by the embryonic vesicle, on uterine contractility on Day 12 (Day 0 = ovulation). Uterine contractility was scored (1 = minimal, 4 = maximal) every 10 min for 1 h and every 30 min for the next hour by a continuous 1-min ultrasound examination of a longitudin...
Factors influencing ovarian activity and sexual behavior of postpartum mares under farm conditions. Management of the postpartum period is one of the most important factors of stud farm medicine. In horses, owing to the long gestation period, the time from parturition to repeat conception needs be short to maintain an optimal yearly foaling interval. For this reason the features of postpartum ovarian activity and sexual behavior were studied under farm conditions. During 2 consecutive breeding seasons, 107 mares on 5 commercial horse farms were monitored after parturition by regular teasing, transrectal ultrasonography and blood sampling for progesterone. Foalings took place from January 1 t...
Dynamics of prostaglandin secretion, intrauterine fluid and uterine clearance in reproductively normal mares and mares with delayed uterine clearance. Two experiments were performed to investigate relationships between oxytocin, prostaglandin release, uterine emptying and fluid accumulation in the uterus. In Experiment 1, the effect of oxytocin on the pattern of prostaglandin release during uterine clearance of radiocolloid was measured in 5 normal mares and 5 mares with delayed uterine clearance. Uterine clearance was measured during estrus by scintigraphy at 0, 60 and 120 min after colloid infusion. After the 120-min reading, 20 IU, i.v., oxytocin were given, and the amount of colloid cleared was measured at 135, 150 and 180 min. Plasma wa...
Heme orientation affects holo-myoglobin folding and unfolding kinetics. Native myoglobin (Mb) consists of two populations which differ in the orientation of the heme by 180 degrees rotation (as verified by nuclear magnetic resonance) but have identical absorption spectra and equilibrium-thermodynamic stability. Here, we report that these two fractions of native oxidized Mb (from horse) both unfold and refold (chemical denaturant, pH 7, 20 degrees C) in two parallel kinetic reactions with rate constants differing 10-fold. In accord, the oxidized heme remains coordinated to unfolded horse Mb in up to 4 M guanidine hydrochloride (pH 7, 20 degrees C).
Study of early pregnancy factor (EPF) in equine (Equus caballus). Early pregnancy factor (EPF) is an immunosuppressive protein detected in the early pregnancy serum. We have already reported that we developed the rosette inhibition test for mare EPF and detected EPF in thoroughbreds. The aim of this study was to determine whether or not our method could be used clinically. Methods: The rosette inhibition test for equine EPF was carried out on serum from six nonpregnant and six pregnant Shetland ponies, a female and a male Chinese pony, and four nonpregnant and 13 pregnant thoroughbred mares. In the thoroughbreds sera were collected during the pregnancy perio...
Proton electron nuclear double resonance from nitrosyl horse heart myoglobin: the role of His-E7 and Val-E11. Electron nuclear double resonance (ENDOR) spectroscopy has been used to study protons in nitrosyl horse heart myoglobin (MbNO). (1)H ENDOR spectra were recorded for different settings of the magnetic field. Detailed analysis of the ENDOR powder spectra, using computer simulation, based on the "orientation-selection" principle, leads to the identification of the available protons in the heme pocket. We observe hyperfine interactions of the N(HisF8)-Fe(2+)-N(NO) complex with five protons in axial and with eight protons in the rhombic symmetry along different orientations, including those of the ...
Sperm transport and survival in the mare: a review. After the deposition of semen in the mare's uterus, spermatozoa must be transported to the site of fertilization, be maintained in the female tract until ovulation occurs, and be prepared to fertilize the released ovum. Sperm motility, myometrial contractions, and a spontaneous post-mating uterine inflammation are important factors for the transport and survival of spermatozoa in the mare's reproductive tract. Fertilizable sperm are present in the oviduct within 4 h after insemination. At this time, the uterus is the site of a hostile inflammatory environment. Our data suggest that spermatozoa...
Current methods for stallion semen cryopreservation: a survey. Various factors affect the success of AI with frozen-thawed semen in horses. Stallion variability is thought to be one of the major factors, but semen processing and evaluation techniques, thawing protocols, packaging systems and timing of insemination are far from standardized among laboratories. Our objective was to survey current methods for stallion semen cryopreservation used commercially around the world. From the answers to the questions in the survey, we attempted to provide an overview of procedures that are standard as well as those that are used by only few laboratories and to revie...
Sperm transport and survival in the mare. Following the deposition of semen in the mares uterus, spermatozoa must be transported to the site of fertilization, be maintained in the female tract until ovulation occurs, and be prepared to fertilize the released ovum. Sperm motility, myometrial contractions, and a spontaneous post-mating uterine inflammation are important factors for the transport and survival of spermatozoa in the mares reproductive tract. Fertilizable sperm are present in the oviduct within 4 hours after insemination. At this time, the uterus is the site of a hostile inflammatory environment. Our data suggest that sperm...
Effect of insemination dose on pregnancy rate in mares. Different insemination doses have been used for artificial insemination(AI) in horses. Since the insemination dose can affect the pregnancy rate, it is important to ensure that an adequate dose be used regardless of the type of inseminationprotocol used. The aim of this study was to find out if it is possible to decrease the insemination dose from 500 x 10(6) progressively motile spermatozoa to 300 x 10(6) progressively motile spermatozoa and still maintain an acceptable pregnancy rate when using extended fresh semen. Thirteen stallions of known fertility and a well-defined group of 64 mares w...
Epididymal maturation affects calcium regulation in equine spermatozoa exposed to heparin and glucose. Spermatozoal function is affected by the ability to regulate intracellular calcium concentrations ([Ca2+]i), and may be influenced by epididymal maturation as well as environmental components. Regulation of [Ca2+]i in ejaculated and epididymal stallion spermatozoa was monitored over time in various media. Spermatozoa from each of 5 pony stallions (3 ejaculate samples and 1 caput and cauda sample) were labeled with the fluorescent calcium indicator probe Indo-1 in a calcium-free modified Tyrode's buffer. Fluorescent emissions were monitored by a dual wavelength spectrofluorometer over 5 h. Calc...
Effect of sperm number and frequency of insemination on fertility of mares inseminated with cooled semen. In this study, we tested the hypothesis that insemination of mares with twice the recommended dose of cooled semen (2 x 10(9) spermatozoa) would result in higher pregnancy rates than insemination with a single dose (1 x 10(9) spermatozoa) or with 1 x 10(9) spermatozoa on each of 2 consecutive days. A total of 83 cycles from 61 mares was used. Mares were randomly assigned to 1 of 3 treatment groups when a 40-mm follicle was detected by palpation and ultrasonography. Mares in Group 1 were inseminated with 1 x 10(9) progressively motile spermatozoa that had been cooled in a passive cooling unit t...
Production of embryos by assisted reproduction in the horse. In vitro embryo production is not yet successful in the horse, largely due to low rates of fertilization in vitro. However, methods to produce embryos from isolated oocytes have been developed. Oocytes may be recovered from living mares by aspiration of the dominant preovulatory follicle by trans-abdominal puncture, and from both preovulatory and immature follicles by trans-vaginal ultrasound-guided puncture. Transfer of in vivo-matured oocytes to the oviducts of bred recipient mares has resulted in good pregnancy rates (75-85%). Little work has been done on transfer of horse oocytes matured i...
Evaluation of two treatments in superovulation of mares. The efficiency of superovulating mares with an enriched fraction of equine follicle-stimulating hormone (feFSH) and an equine pituitary extract (EPE) with similar FSH content but differing in the LH amount was compared. Mares were randomly assigned to an feFSH (n = 5) or EPE (n = 5) treatment. The experimental period was of 2 successive estrous cycles, with the first cycle as the control. At Days 6 and 7 of the estrous cycle, the mares received 250 micrograms i.m. cloprostenol. The treatments consisted of daily injections of 25 mg feFSH or EPE beginning on Day 6 post ovulation. Mares were inse...
Transrectal color Doppler sonography of the A. uterina in cyclic mares. Color Doppler ultrasound was used transrectally in 6 mares to locate both the left and right Aa. uterinae and to obtain flow velocity waveforms at defined times (Days 0, 5, 10, 15 and 20) during 4 estrous cycles. Blood flow reflected by the resistance index (RI) was determined for both arteries on 120 occasions. As there was no significant difference and a high correlation in the RI values between the left and right arteries (paired Student's t-test, correlation coefficient r > 0.94; P < 0.05), the average RI value was used for subsequent analyses. There were correlations between RI valu...
Effect of mare’s age and recovery methods on the recovery rate of equine follicular oocytes for IVM procedures. Mares (n = 39) were classified according to age as young (less than 1.5 yr, n = 17) or old (more than 1.5 yr, n = 22) and sacrificed. Ovaries were measured and weighed, and the number of follicles and CL were counted. Follicle size and distribution were recorded (external: > 20 mm, 5 mm, < 5 mm). External follicles were aspirated while internal follicles were sliced. The number and Type of oocytes recovered using each method were recorded. Oocyte recovery rates (oocytes/ovary) resulted in a mean of 0.92 oocytes by aspiration and 1.36 oocytes by additional slicing. The mean numbers of av...
Effects of melatonin implants in pony mares. 1. Acute effects. The effects of melatonin implant treatment over a four week period on LH, estradiol (E2) and progesterone (P4) secretion during the breeding season were studied in ovary-intact and ovariectomized pony mares. Mares with melatonin implants had significantly higher daytime melatonin concentrations than mares with sharm implants (P = 0.0065). In ovariectomized mares, LH secretion did not differ between mares with melatonin and sham implants. In ovary-intact mares, melatonin implants altered the pattern of LH secretion (P = 0.0023) in such a way that an increase in LH secretion was observed during ...
A biomechanical comparison of double-plate and Y-plate fixation for comminuted equine second phalangeal fractures. To compare the biomechanical properties, in full limb preparations, of intact second phalanx and a simulated comminuted second phalangeal fracture stabilized with either two bone plates or a custom Y-plate. Methods: In vitro biomechanical assessment of intact limbs and of paired limbs with a simulated second phalangeal fracture stabilized by one of two fixation methods. Animal Population-Thirteen pairs of equine cadaveric forelimbs. Methods: A comminuted second phalangeal fracture was created in six paired cadaveric limbs. For each limb pair, the fracture was stabilized with two plates in one ...
