Analysis of gene and protein expression in the endometrium for validation of an ex vivo model of the equine uterus using PCR, digital and visual histopathology.

In the past, most research in equine reproduction has been performed in vivo but the use of in vitro and ex vivo models has recently increased. This study aimed to evaluate the functional stability of an ex vivo hemoperfused model for equine uteri with molecular characterization of marker genes and their proteins. In addition, the study validated the respective protein expression and the aptness of the software QuPath for identifying and scoring immunohistochemically stained equine endometrium. After collection, uteri (n = 12) were flushed with preservation solution, transported to the laboratory on ice, and perfused with autologous blood for 6 h. Cycle stage was determined by examination of the ovaries for presence of Graafian follicles or corpora lutea and analysis of plasma progesterone concentration (estrus: n = 4; diestrus: n = 4; anestrus: n = 4). Samples were obtained directly after slaughter, after transportation, and during perfusion (240, 300, 360 min). mRNA expression levels of progesterone (PGR), estrogen (ESR1) and oxytocin (OXTR) receptor as well as of MKI67 (marker of cell growth) and CASP3 (marker of apoptosis) were analyzed by RT-qPCR, and correlation to protein abundance was validated by immunohistochemical staining. Endometrial samples were analyzed by visual and computer-assisted evaluation of stained antigens via QuPath. For PGR, effects of the perfusion and cycle stage on expression were found (P < 0.05), while ESR1 was affected only by cycle stage (P < 0.05) and OXTR was unaffected by perfusion and cycle stage. MKI67 was lower after 360 min of perfusion as compared to samples collected before perfusion (P < 0.05). For CASP3, differences in gene expression were found after transport and samples taken after 240 min (P < 0.05). Immunohistochemical staining revealed effects of perfusion on stromal and glandular cells for steroid hormone receptors, but not for Ki-67 and active Caspase 3. OXTR was visualized in all layers of the endometrium and was unaffected by perfusion. Comparison of QuPath and visual analysis resulted in similar results. For most cell types and stained antigens, the correlation coefficient was r > 0.5. In conclusion, the isolated hemoperfused model of the equine uterus was successfully validated at the molecular level, demonstrating stability of key marker gene expression. The utility of computer-assisted immunohistochemical analysis of equine endometrial samples was also confirmed.

Success of different therapies for bacterial endometritis in stud farm practice.

Bacterial endometritis is a major problem in equine reproduction usually treated with antibiotics, however reports of success rates are scarce. This study collected data from mares diagnosed with intrauterine bacterial growth and compared the outcome of different therapies for bacterial endometritis in German stud farm practice. Data on mares with positive uterine culture results were collected retrospectively in veterinary practices (n = 5; 2018-2022). Information relating to 30 factors (mare, diagnostics, therapy, pregnancy rate) of bacterial endometritis cases (n = 772) were recorded and analyzed. Possible effects on treatment success (positive pregnancy result in the first cycle after treatment) were tested by binomial logistic regression. In most cases ß-hemolytic streptococci were detected (n = 707). Treatments for the endometritis included trimethoprim-sulfonamides (n = 409), procaine-penicillin (n = 227), marbofloxacin (n = 53) or no antibiotics (n = 59) and most antibiotics were administered systemically (n = 711) rather than locally (n = 23). Uterine lavage was reported in 49 % of mares. Uterotonic drugs were administered in 42.2 % of mares. Breeding programs included artificial insemination (AI) with chilled semen (n = 667), AI with frozen semen (n = 169), transfer of fresh (n = 112) or cryopreserved (n = 27) embryos and natural cover (n = 27). In the first cycle after treatment, the pregnancy rate was 47 % and it rose to 69 % by end of the season. Treatment success was affected by duration of antibiotic treatment, veterinary practice, and presence of clinical signs. In conclusion, reported treatment practices in German stud farm practice resulted in acceptable pregnancy results and the multiple binomial logistic regression approach identified factors affecting the pregnancy outcome in this dataset.

Frequency of potentially pathogenic bacterial and fungal isolates among 28,887 endometrial samples from mares, with an emphasis on multi-drug resistant bacteria in Germany (2018-2022).

Antimicrobial-resistant bacteria pose a serious threat to the wellbeing of animals and humans. In equine reproduction, endometritis caused by facultative microbial pathogens is a condition, which is usually treated with antibiotics. Data from Germany on prevalence of facultative pathogenic microorganisms cultured in samples from the equine uterus and the frequency of multi-drug resistant (MDR) bacteria is lacking. The aim of the study was to provide representative numbers for both. Microbiological culture results (n = 28,887) of endometrial samples submitted to a large veterinary diagnostic laboratory from 2018-2022 were analyzed. An average of 25.9 % of the culture results showed growth of facultative pathogenic bacteria. The dominant isolated bacteria were ß-hemolytic streptococci (79.7 %) followed by Escherichia (E.) coli variatio haemolytica (5.2 %). E. coli were cultured in 4.3 % of the samples and occurred more often than Klebsiella pneumoniae (3.9 %), Candida species (2.9 %), Pseudomonas aeruginosa (2.0 %), and Staphylococcus aureus (1.5 %). Antibiotic susceptibility testing revealed sensitivity of ß-hemolytic streptococci towards penicillins in almost 100 % of the cultured samples (99.5 %). E. coli-isolates were sensitive to gentamicin in 96.2 % of the cases. The frequency of multidrug-resistant extended spectrum beta-lactamase (ESBL)-positive bacteria and methicillin-resistant Staphylococcus aureus (MRSA) was 3.1 % of all positive culture results. The number of ESBL-positive isolates (n = 159) and MRSA was stable from 2018-2022. In conclusion, the situation regarding occurrence of MDR bacteria in Germany is favorable, but should further be monitored.

Flow cytometric detection and identification of different leukocyte subpopulations in stallion semen.

To improve accuracy in evaluating stallion ejaculates, an antibody-based, flow cytometric assay for the detection and identification of leukocyte subpopulations (CD4-, CD8-, CD21-, CD172a-positive cells) in stallion semen (n = 12) was established. For establishment of the assay, native semen was supplemented with blood leukocytes (control: 20% leukocytes, 80% sperm cells) and analysed by flow cytometry. Adding antioxidants (ascorbic acid and butylated hydroxytoluol) to semen immediately after collection inhibited rapid death of lymphoid cells in sperm leukocyte mixtures. In control set-ups, 27.85 ± 5.7% of events were positive for CD4, CD8, CD21 or CD172a, while in native semen samples, leukocytes were scarce (0.114 ± 0.134%). The most abundant leukocyte subpopulation in semen was of lymphoid origin (CD4-positive cells [0.015 ± 0.02%]), whereas CD21-positive cells (B cells; 0.001 ± 0.001%) were virtually absent in ejaculates of fertile stallions. This presented flow cytometric assay for the detection and identification of different leukocyte population in equine antioxidant-treated ejaculates can be used as an additional tool for spermatological examination in stallions.

Comparison of systemic trimethoprim-sulfadimethoxine treatment and intrauterine ozone application as possible therapies for bacterial endometritis in equine practice.

Bacterial endometritis is one of the major problems in equine reproduction and usually treated with antimicrobial drugs. The study aimed to compare the effects of intrauterine ozone application and systemic antibiotic treatment (trimethoprim-sulfadimethoxine) on intrauterine bacterial growth and possible side effects on the endometrium in a clinical setting. Mares (n = 30) with signs of endometritis (positive uterine bacterial culture and cytological findings) were assigned randomly to different treatments: intrauterine insufflation of an ozone-air-mix (240 ml, 80 µg ozone/ml) twice at a 48 h-interval (Ozone; n = 10), systemic antibiotic therapy with trimethoprim-sulfadimethoxine (30 mg/kg, p.o., twice daily) for 5 days (TMS; n = 10), or intrauterine insufflation of air (240 ml, sterile-filtered) twice at a 48 h-interval (air; n = 10). Endometrial biopsy for histological examination was obtained before the treatment. Histological examination revealed no differences among groups. A control examination, including transrectal ultrasound, bacterial culture, cytological evaluation, and biopsy, was performed 7 days after the last treatment. Overall bacterial growth was reduced in every group after the treatment (p < 0.05), irrespective of the therapy [Ozone: 4/9 (positive culture after treatment/number of mares), TMS: 3/10 and Air: 6/10; p > 0.05]. However, Ozone and TMS (p < 0.05) were more effective in reducing growth of gram-negative bacteria as compared to Air (p > 0.05). No effects on the number of polymorphonuclear granulocytes (cytology) were observed (p > 0.05). In conclusion, trimethoprim-sulfadimethoxine and intrauterine ozone insufflation are safe treatment options for bacterial endometritis in mares but the efficacy of both treatments in reducing bacterial growth did not result in a complete absence of intrauterine bacterial growth.

Evaluation of an ex vivo model of the blood-perfused equine uterus.

Uterine pathologies are the most common causes of infertility in mares. This study aimed to establish an ex vivo blood-perfused model for equine uteri and investigate the possible effects of different cycle stages (estrus, diestrus and anestrus) on the applicability of the model. Uteri (n = 13) were collected at an abattoir, flushed with preservation solution, transported to the laboratory on ice, and isolated perfused with autologous blood for 6 h (n = 12). For negative control, one uterus was handled as described but left without perfusion for 6 h. The cycle stage was determined by examination of the ovaries for the presence of Graafian follicles or corpora lutea and analysis of plasma progesterone concentration (estrus: n = 4; diestrus: n = 4; anestrus: n = 4). Sonomicrometry crystals were implanted into the myometrium to record spontaneous contractions and the response to 0.5 IU oxytocin after 6 h of perfusion. Analyses of the arterial and venous perfusate were performed every hour to determine glucose consumption, lactate production, pH, lactate dehydrogenase activity (LDH), and potassium concentration (K+). Biopsy samples were obtained directly after slaughter, after transportation, after equilibration, after 4, 5, and 6 h of perfusion, and immediately after removal from the perfusion system. The uteri's glucose consumption and lactate production increased over time (p < 0.05), but no differences among cycle stages were detected. pH (arterial and venous) increased over time (p < 0.05). No changes for LDH were observed. K+ increased after 4 h of perfusion (p < 0.05), but was unaffected by the cycle stage. Spontaneous contractions were present in all perfused uteri, but myometrial activity in the negative control was limited to the 2nd hour of perfusion. No effects of cycle stage on contraction amplitude and duration after oxytocin administration were detected. The cycle stage did not affect frequency (except after 5 h of perfusion), amplitude, duration of contractions, or edema formation. Histology revealed congestion of endometrial capillaries after 4, 5, and 6 h perfusion time. In conclusion, the ex vivo model was capable of supporting the functionality of equine uteri for 6 h. However, viability and histomorphology of the endometrium appeared to be impaired after 4 h of perfusion. Effects of the cycle stage on the applicability of the model were absent.

Psychosocial functioning as a personal resource promoting a milder course of schizophrenia.

Schizophrenia has been shown repeatedly to be associated with a low level of psychosocial functioning. It is assumable that psychosocial functioning is related not only to current, but also to future symptom severity. To test this assumption, a follow-up study with two measurement time points with an interval of 18 months was conducted. In total, 154 inpatients from five psychiatric hospitals with a diagnosis of a schizophrenic disorder took part at both visits. Psychosocial functioning was measured with the Personal and Social Performance Scale (PSP scale) at baseline, and schizophrenic symptoms were assessed with the Positive and Negative Syndrome Scale (PANSS) at baseline and at follow-up. Two PSP subscales, i.e. socially useful activities and control over disturbing and aggressive behavior, turned out to be significant predictors of symptom severity 18 months later. The findings reveal that personal resources in the occupational domain and in adequate interpersonal behavior can have a positive impact on the long-term course of schizophrenia.

[Changes in the Practice of Involuntary Hospitalization During the COVID-19 Pandemic - Experiences and Opinions of Chief Psychiatrists]. / Veränderungen in der psychiatrischen Unterbringungspraxis während der COVID-19-Pandemie.

OBJECTIVE: To collect experiences and opinions of chief psychiatrists in relation to changes in the practice of involuntary hospitalization during the COVID-19 pandemic. METHODS: Online survey among members of the Association of Chief Physicians for Psychiatry and Psychotherapy in North Rhine-Westphalia (LLPP) and analysis of protocols of LLPP board meetings. RESULTS: Changes in the practice of involuntary hospitalization have been perceived in contexts with and without direct reference to COVID-19. These changes have affected, among other things, judicial hearings as well as decisions about the use of coercive measures. CONCLUSION: Procedural standards for involuntary hospitalization must be maintained and coercive measures may only be used if they meet the applicable ethical and legal requirements. It must be ensured that people with mental disorders are not treated unequally both when taking and withdrawing restrictive measures to contain the pandemic.

Occurrence of Intrauterine Purulent Concrements in a Maiden Mare-A Case Report.

Pyometra is an uncommon condition in mares associated with various symptoms. Here, we report a case of a 13-year-old Icelandic barren maiden mare with recurrent vaginal discharge. Ultrasonographically, the mare displayed intrauterine spherical masses of inhomogenous texture, which were identified as purulent concrements in hysteroscopy. The purulent concrements were successfully removed via uterine lavage after endoscope-assisted comminution. Microbiologic examination of the concrements revealed growth of Streptococcus equi subspecies zooepidemicus, Actinobacillus species, Pseudomonas aeruginosa, Staphylococcus intermedius, Pseudomonas fulva, Citrobacter freundii, and Chryseobacterium species. Systemic antibiotic treatment with trimethoprim-sulfadiazine and additional uterine lavages were performed for 10 days. A follow-up examination revealed absence of intrauterine masses but reoccurrence of pyometra due to an impatent cervical canal. The pyometra condition was resolved by insertion of a cervical stent for prevention of intrauterine fluid accumulation. In conclusion, uterine masses, which may severely impact fertility, are best diagnosed by hysteroscopy. Intrauterine purulent concrements should be considered as an atypical form of equine pyometra.

Diagnostic and Treatment Practices of Equine Endometritis-A Questionnaire.

Endometritis is a major cause for impaired fertility in mares. The objectives of this study were to collect information on diagnostic and treatment practices performed by veterinarians and to investigate possible effects of professional experience, caseload, and geographical location on the practitioners' management of endometritis cases. For this purpose, equine practitioners (n = 680) were asked to fill out an online survey (34 questions). The online survey yielded 117 responses by veterinarians practicing in all parts of Germany. Most respondents came from Lower Saxony and managed <20 mares per year. For the diagnosis of chronic infectious endometritis, uterine sampling for microbiological examination was performed manually with a swab by the majority of practitioners whereas only few used the speculum technique. The incidence of antibiotic resistant pathogens was reported to be <5% by almost all respondents. Most practitioners relied on systemic antibiotic treatment with trimethoprim-sulfadiazine. Only occasionally veterinarians used intrauterine antibiotic therapy. Uterine lavages were performed routinely by almost half of the respondents in case of positive uterine cultures, mostly with 0.9% saline solution. Irritant solutions (e.g., iodine, chlorhexidine, kerosene) were used less often. Collection of an endometrial culture after completion of the treatment was common practice. While only a very limited association of the geographical location of practitioner (e.g., on selection of mares for endometrial culture, p < 0.05) was observed, the number of managed mares affected the answers notably (e.g., for use of irritating intrauterine treatment, p < 0.05). The management of persistent breeding induced endometritis (PBIE) was influenced by the number of managed mares (e.g., for use of oxytocin, p < 0.05) and 29.6% of respondents administered antibiotics as part of their PBIE management. In summary, treatment strategies in the field vary considerably and include also non-evidence-based methods, but most German practitioners apply the recommended suitable treatments. Following the guidelines for antibiotic usage, most veterinarians administer antibiotics dependent on endometrial culture results but do not use cytology, low-volume lavage, or biopsy routinely. Antibiotic resistant uterine pathogens are reported to be isolated infrequently and equine practitioners prefer systemic to local antibiotic treatment of endometritis.

Effects of Hysteroscopic and Uterine Body Insemination on the Presence of Selected Immune Cells in the Equine Endometrium.

The effects of standard uterine body and hysteroscopic insemination on endometrial health were investigated. For this purpose, 33 mares were assigned to five different protocols: control (no insemination; n = 7), sham AI (sham uterine body insemination; n = 6), sham HysAI (sham hysteroscopic insemination; n = 7), standard AI (standard uterine body insemination, 300 × 106 progressively motile sperms (PMS); n = 7) and HysAI (hysteroscopic insemination, 100 × 106 PMS; n = 6). Sampling included uterine swabbing for microbiological examination, cytology for determination of polymorphonuclear neutrophils (PMNs) in the uterus, and endometrial biopsy collection for histology and characterization of endometrial immune cells on day 18 after ovulation (B1) as well as 8-10 hours (B2, day 20) and 72 hours after insemination (B3, day 23). Microbial contamination increased throughout the experiment in the sham insemination groups. Significant effects (P < .05) over time were detected for PMNs (cytology: sham HysAI, standard AI, and HysAI; histology: standard AI and HysAI), macrophages (immunohistochemistry: standard AI and HysAI) and T cells (immunohistochemistry: standard AI), showing an increase at B2 and a subsequent decrease toward baseline levels at B3. At B2, significant differences (P < .05) existed for PMNs (mean ± SEM) between control (1.3 ± 1.9%) and sham AI (2.2 ± 2.7%) versus standard AI (12.2 ± 4.7%) and for macrophages between control (4.1 ± 3.5%) and sham AI (2.5 ± 1.3%) versus standard AI (25.4 ± 15.8%). Thus, the cellular immune response of the endometrium depends on sperm deposition in the uterus and does not differ between hysteroscopic and standard uterine body insemination.

[Adenomatous hyperplasia of equine allantoic epithelium - a warning sign? - A case report]. / Die equine adenomatöse Allantoishyperplasie ­ ein Warnsignal?

Adenomatous hyperplasia of the equine allantoic epithelium (EAAH) is an infrequently observed nodular or plaque-like change in the placenta of the mare which is presented as a case description. EAAH is most frequently diagnosed in cases of aborted fetuses and is associated with inflammatory changes of the placenta. Histologically, different degrees of EAAH may be distinguished; however, these are not associated with specific clinical signs, degree of inflammation, a particular pathogen, or the frequency of abortions. It is assumed that EAAH represents a secondary, reactive change and has per se no influence on the vitality of the fetus itself. The lesion, however, should be taken seriously and considered as a warning sign for possible previous subclinical infections, even in clinically normal foals. This in turn should prompt more detailed clinical examination and monitoring of the mare and foal.

Effects of dietary L-arginine supplementation to early pregnant mares on conceptus diameter-Preliminary findings.

The importance of the amino acid L-arginine (ARG) for conceptus growth and litter size has been demonstrated in various species. L-arginine is part of embryo-derived polyamines, a substrate for nitric oxide synthase and stimulates protein synthesis by the embryo. In the present study, we have investigated whether dietary L-arginine supplementation stimulates early conceptus growth in mares. Warmblood mares with singleton pregnancies received either an arginine-supplemented diet (approximately 0.0125% of body weight, n = 12) or a control diet (n = 11) from days 15 to 45 after ovulation. Diameter of the embryonic vesicle (days 14, 17, 20 of pregnancy) and size of the embryo respective foetus (length and maximal diameter, days 25-45 of pregnancy at 5-day intervals) were determined by transrectal ultrasound. At foaling, weight and size of the foal and the placenta were determined. Blood for determination of equine chorionic gonadotrophin (eCG) and progestin concentrations was collected repeatedly. Neither eCG nor progestin concentration in plasma of mares differed between groups at any time. No effects of arginine treatment on diameter of the embryonic vesicle between days 14 and 20 of pregnancy were detected. Diameter of the embryo/foetus on days 40 to 45 of pregnancy strongly tended to be enhanced by arginine supplementation (p = 0.06). Weight and size of neither the foal nor placenta at birth differed between groups. In conclusion, L-arginine supplementation was without negative effects on early equine embryos and may support embryonic growth at the beginning of placentation.

Electrical Conductivity Modeling of Graphene-based Conductor Materials.

Graphene-based conductors such as films and fibers aim to transfer graphene's extraordinary properties to the macroscopic scale. They show great potential for large-scale applications, but there is a lack of theoretical models to describe their electrical characteristics. We present a network simulation method to model the electrical conductivity of graphene-based conductors. The method considers all of the relevant microscopic parameters such as graphene flake conductivity, interlayer conductivity, packing density, and flake size. To provide a mathematical framework, we derive an analytical expression, which reproduces the essential features of the network model. We also find good agreement with experimental data. Our results offer production guidelines and enable the systematic optimization of high-performance graphene-based conductor materials. A generalization of the model to any conductor based on two-dimensional materials is straightforward.

Anti-Müllerian hormone profiling in prepubertal horses and its relationship with gonadal function.

Anti-Müllerian hormone (AMH) has gained increasing interest as a biomarker for assessment of gonadal activity. The ability to predict the ovarian follicular reserve of prepubertal female horses (fillies) or to identify stallions with testicular pathologies already during their prepubertal life has not been analyzed so far. Both would help to select fertile horses and reduce costs associated with keeping animals. The objectives of the present study were to (1) assess AMH, LH, FSH, progesterone (females) and testosterone (males) dynamics in prepubertal horses from birth onwards and (2) determine whether AMH concentrations detected in plasma of prepubertal female and male horses are correlated with postpubertal gonadal development. Warmblood foals (n = 30, 14 females, 10 normal males and 6 males with abnormal testicular development) born between February and May of two consecutive years (n = 28 in the first year and n = 2 the next year), were included in the study. Information on gestational length, parity of the dam and placental weight was collected for all foals. Blood samples for hormone analysis were collected from birth onwards every four weeks up to the age of one year. At two years, blood samples were collected on the day when antral follicle count (AFC) and total testicular volume (TTV) were assessed. AMH was detectable in the plasma of all animals from birth onwards and its concentration was significantly higher (P < .001) in males than in females, regardless of testicular development. In males, AMH and testosterone concentration were similar for all animals during the first year of life, regardless of testicular development. At two years, AMH concentration was higher (P < .05) in males with abnormal testicular development than in those with normal testes. In females, AMH concentration at two years was correlated with AMH concentration at birth (P < .05) and with AFC (P < .001). At birth, LH concentration was lower (P < .05) in stallions with abnormal testes (0.3 ±â€¯0.2 ng/ml) than in controls (0.6 ±â€¯0.2 ng/ml). A high negative correlation between AMH concentration and gestation length was observed in males during the first eight weeks of life (P < .01, r = -0.64 to -0.71). Elevated progesterone concentrations over 1 ng/ml were observed in several females starting with 20 weeks of age. This was paralleled by an increase in AMH concentration and was preceded by FSH and LH increases. In conclusion, AMH determination can be reliably used from two years onwards to identify stallions with abnormal testicular development, but it is inconclusive before puberty. In female horses, determination of AMH concentration at a prepubertal age allows for prediction of AMH and AFC after puberty. We suggest that premature luteinisation occurs before the onset of puberty in female horses and that LH secretion in the perinatal period is involved in testicular development and descent in the horse.

Effects of periovulatory gonadotrophin treatment on luteal function and endometrial expression of selected genes in cyclic pony mares.

Progestin concentration in plasma during the early luteal phase is crucial for endometrial function and conceptus development. We hypothesized that periovulatory gonadotrophin treatment via support of luteal function affects endometrial gene expression in horses. Effect of age was analyzed as well. Shetland mares (n = 8, age 4-25 years) were assigned to the following treatments during five consecutive cycles in alternating order following a cross-over design: treatment hCG/-: preovulatory injection of hCG, but no gonadotrophin injection at detection of ovulation, treatment -/hCG: no preovulatory gonadodrophin injection, but injection of hCG at detection of ovulation, treatment eCG/-: preovulatory injection of eCG, but no gonadotrophin injection at detection of ovulation, treatment -/eCG: no preovulatory gonadotrophin injection, but injection of eCG at detection of ovulation, treatment control: no treatment. Concentration of progestin was analyzed by ELISA from the day of ovulation until Day 10. On Day 10, endometrial cells were collected transvaginally by cytobrush technique. Expression of mRNA of cyclooxygenase-2 (COX-2), prostaglandin F2α-synthase, prostaglandin E-synthase, progesterone receptor (PR), estradiol receptor (E2R), acyl-CoA-dehydrogenase (ACAD), uteroglobin (UGB), uteroferrin, and uterocalin was analyzed by RT qPCR. Immunohistological staining of endometrial tissue, obtained via biopsy, was performed for COX-2, PR and UGB. The P4 concentration was influenced by day of cycle (P < 0.01), but not by treatment. No effects of age on gene expression were determined. Neither of the periovulatory gonadotrophin treatments nor age influenced mRNA expression of the genes of interest. Treatment did also not affect immunohistological staining of the endometrium. In contrast, age affected the percentage of PR positive stromal cells (e.g. mare 1 (4 years): 65.5 ± 2.6, mare 2 (24 years): 82.7 ± 2.2%, P < 0.05) and COX-2 positive stained ciliated cells (e.g. mare 1: 15.8 ± 2.9, mare 2: 33.4 ± 6.0%, P < 0.05). In conclusion, no effects of periovulatory gonadotrophin treatment and age on endometrial gene expression in luteal phase pony mares were reported. A lack of treatment effects on luteal function and expression of PRs in the endometrium can at least in part be explained by differences in the reproductive physiology between horses and ponies.

Treatment with human chorionic gonadotrophin before ovulation increases progestin concentration in early equine pregnancies.

For prevention of early conceptus loss in the horse, treatment with progestins has become common practice. In cattle, treatment with human chorionic gonadotrophin (hCG) during the early postovulatory phase stimulates endogenous progesterone synthesis, which is an important factor for maintenance of early pregnancy via stimulation of endometrial function and conceptus development. In the present study we have therefore investigated the influence of treatment with hCG either for induction of ovulation or during the early luteal phase on plasma progestin concentrations, size of the corpus luteum and size of the conceptus in early pregnant mares. We hypothesized that hCG treatment stimulates progestin secretion and conceptus development. In Experiment 1, induction of ovulation with hCG (1500 IU i.v.; n=14) significantly increased progestin concentration between days 5 and 15 after ovulation compared to untreated controls (n=28; p<0.05; e.g. day 5 hCG i.v.: 17.2 ± 1.9, control: 13.9 ± 0.8 ng/ml). A significant interaction (p<0.05) of hCG treatment with size of the conceptus between days 30 and 40 of pregnancy was detected. In Experiment 2, treatment of mares with hCG (5000 IU) on day 5 after ovulation (n=12) did neither affect progestin secretion (e.g. day 8 hCG: 15.4 ± 1.6, control: 17.6 ± 1.2 ng/ml) nor luteal tissue area (e.g. day 8 hCG: 9.0 ± 0.7, control: 7.6 ± 1.4 cm(2)) compared to untreated mares (n=9). In conclusion, treatment of mares with hCG for induction of ovulation within 48 h before ovulation but not on day 5 of the luteal phase stimulates progestin secretion and may enhance conceptus development via stimulation of endometrial function during early pregnancy.