Omneity® Pellets
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Topic:Reproduction
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.
In-vitro and in-vivo responsiveness of the corpus luteum of the mare to gonadotrophin stimulation. Dispersed horse luteal cells were used to evaluate the ability of horse LH, hCG and PMSG to stimulate progesterone secretion in vitro. Morphological characterization of these cells before gonadotrophin stimulation indicated the presence of two populations of cells based on cell diameters. In luteal cells incubated as suspended cells, horse LH and hCG stimulated (P less than or equal to 0.05) progesterone production at all levels of treatment. Stimulation of progesterone secretion by hCG was greater (P less than or equal to 0.05) than by horse LH over the range of concentrations utilized. When ...
Evaluation of the expression of a male-specific antigen on cells of equine blastocysts. This experiment was designed (1) to determine if H-Y antigen is expressed on the cell surface of pre-implantation equine blastocyst stage embryos, (2) if so, to identify differences in expression on inner cell mass (ICM) verses trophectoderm cells and (3) to evaluate whether the detection of this glycoprotein would aid in the identification of equine embryonic sex. A total of 33 blastocyst stage horse embryos were collected 6-7 days post-ovulation by trans-cervical flush and were immediately evaluated for the presence of H-Y antigen. Additionally, 17 embryos, collected at similar stages and cu...
Histopathologic effects of dimethyl sulfoxide on equine endometrium. Endometrial fibrosis is a major cause of infertility in broodmares. Because of the proven anti-inflammatory effects of dimethyl sulfoxide (DMSO) and its influence on collagen, the effect of DMSO on the endometrium was investigated in mares. Solutions of DMSO (25%, 50%, or 75%) were infused into the uterus of clinically normal mares. Examination of serially obtained biopsy specimens revealed epithelial ulceration and stromal inflammation that were proportional to the DMSO concentration infused, but vasodilatation was not observed. In all mares, the endometrium had returned to normal by day 21 a...
Treatment of a ruptured medial collateral ligament of the stifle in a horse. Medial collateral ligament ruptures in horses are rare and difficult to treat. Conservative treatment usually results in degenerative joint disease that causes permanent lameness. Surgical treatment may be an alternative for salvaging horses for breeding purpose.
Isolation and characterization of monoclonal antibodies against an attenuated vaccine strain of equine herpesvirus type 1 (EHV-1). The production and differentiation of monoclonal antibodies (mabs) against the Rac-H strain of EHV-1 used as an attenuated live vaccine to prevent rhinopneumonitis and abortion is described. Seven different antigenic sites were detected by the 15 mabs produced. EHV-1 specific mabs as well as EHV-1 and -4 common mabs could be established, allowing easy typing of EHV isolates. One mab recognized the vaccine strain only. This reaction was used to investigate a possible involvement of the vaccine strain in cases of abortion. Common antigenic determinants with EHV-1,-3,-4 and BHV-1 could also be de...
Effect of ovarian steroids on migration of uterine lumenal neutrophils and on chemokinetic factors in uterine secretions from mares. Incubation of blood neutrophils with uterine flushings collected from ovariectomised mares treated with oestradiol, stimulated migration under agarose, whereas flushings from mares treated with progesterone or oily vehicle, inhibited migration. After intra-uterine infusion of bacteria, however, flushings from oestradiol-treated and vehicle-treated mares inhibited migration, whereas progesterone treatment stimulated migration. Migration of uterine-derived neutrophils under agarose was less than that of blood neutrophils and was not influenced by treatment with ovarian steroids. Uterine suscepti...
Application of cloned fragments of equine herpesvirus type-1 DNA for detection of virus-specific DNA in equine tissues. Tissue specimens obtained from equine herpesvirus-1 (EHV-1), subtype 1-infected aborted foetuses were analysed for the presence of virus DNA by means of Southern blot and dot blot hybridisations. The specificity of the methods was confirmed although the sensitivity was inferior to classical techniques such as virus isolation. However, the possibility of detecting the state of the virus DNA and the ability to distinguish between subtypes were important features, and the dot blot method was shown to have potential for a rapid diagnostic test. This report demonstrates some potential practical app...
Restricted conceptus mobility results in failure of pregnancy maintenance in mares. Cycling pony mares were bred and used to test the effect of restricted conceptus mobility on luteal maintenance (i.e. maternal recognition of pregnancy). In Experiment 1, uterine horns were ligated to restrict conceptus mobility to one uterine horn, Group 1; one horn plus the uterine body, Group 2; or one horn, the body and approximately 80% of the second horn, Group 3. Pregnancies were monitored with real-time ultrasonography. Four of five mares in Group 1 and two of four mares in Group 2 returned to estrus (Day 16.0 +/- 1.9 and 14.5 +/- 0.7, respectively) and subsequently lost the embryonic ...
Concentration of serum testosterone in XY sex reversed horses. The XY Sex Reversal Syndrome of the horse is a condition associated with female or intersexual development in genetic males. In our previous study, 38 sex reversed XY mares were classified according to behavior, gross clinical phenotype, gonadal status, and H-Y phenotype. Four classes were described, ranging from potentially fertile female (Class I) to virilized intersex (Class IV). In the present study, serum testosterone concentrations were measured in 29 sex-reversed XY mares, 3 normal mares and 3 normal stallions. Serums were obtained during the breeding season (March-August), and were sto...
The effect of detomidine (Domosedan) on the maintenance of equine pregnancy and foetal development: ten cases. Detomidine was administered throughout 10 pregnancies in eight mares. An intravenous injection of 20 micrograms/kg body weight was given weekly from Day 14 to Day 60 of gestation and thereafter every four weeks until parturition. One mare suffered torsion of the large colon and was destroyed on Day 86; the foetus was normally developed. A further mare aborted at 167 days. The remaining eight pregnancies continued to full term. One foal was delivered by caesarean section because of torticollis and, of the seven foals born spontaneously, one had bilateral upward patellar fixation at one month ol...
Pre-chemotactic and chemotactic properties of uterine fluid from mares with experimentally induced endometritis. Streptococcal endometritis was induced experimentally in pony mares during oestrus. Uterine fluid was collected 30, 60, 120 or 240 minutes later and tested for its effect on the in vitro morphology and chemotaxis of equine neutrophils by two independent methods. The maximal response occurred between 30 and 60 minutes after infection and persisted until 240 minutes. The chemo-attractant contained both heat labile and heat stable components and the latter appeared to be active at low concentrations.
Equine endometrial cytology. The simplicity of collection of material for cytologic preparations belies the complexity of smear interpretation beyond recognition of neutrophils. Knowledge concerning cancer cytology moves rapidly, for cancer is a progressive, often fatal disease so that tissue for comparison and confirmation of interpretation often becomes available. This is not true for cytologic study of the equine endometrium. Lesions detected by means of cytology smears may be transient and regress, offering little information concerning their etiology or consequences. They may be focal and missed in the corresponding ...
Reproductive physiology of the nonpregnant mare. An overview and update. This article reviews the reproductive events in the nonpregnant mare with emphasis on recent advances. The discussion is restricted to the salient features of puberty (prenatal and prepubertal events), seasonality (gonadotropins, photoperiod, and other modifying factors), and the estrous cycle (hormones, estrus, diestrus, and the control of cyclicity) in the nonpregnant mare.
Uterine defense mechanisms in the mare. Uterine defense against infection in the mare has been actively investigated over the past decade. Mechanisms of defense, including the role of immunoglobulins, polymorphonuclear neutrophils, and the physical ability of mares to eliminate bacteria from the uterus, are discussed.
XY sex reversal syndrome in the mare: clinical and behavioral studies, H-Y phenotype. An inherited genetic disorder causes XY embryos of the horse to develop as mares. On the basis of our study of 38 such mares, we have identified four grades or classes of XY sex reversal according to this scheme: class I, nearly normal female, of which some are fertile; class II, female with gonadal dysgenesis, normal mullerian development; class III, intersex mare with gonadal dysgenesis, abnormal mullerian development, enlarged clitoris; class IV, virilized intersex characterized by high levels of testosterone. In general, class I and class II mares were typed H-Y antigen-negative whereas cl...
Control of the estrous cycle in the mare. All current approaches to manipulating the reproductive biology of the nonpregnant mare are discussed.
