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The path to fertility in the mare requires an understanding of the hormonal influences, the immune response, genetics, and epigenetic mechanisms involved not only in physiological reproductive processes, but also such pathologies as endometritis and endometrosis. Endometritis may lead to endometrosis establishment. In the presence of endometritis, neutrophils arrive at the mare endometrium, and form neutrophil extracellular traps. While NETosis plays pivotal roles, prolonged inflammation can lead to chronic endometritis, endometrosis, and fertility issues. Matrix metalloproteinases and epigenetic changes influence the course of endometrosis. Inhibitors of specific enzymes involved in NETosis and epigenetic inhibitors have shown potential in reducing pro-fibrotic effects. Collagen type III (COL3) has emerged as a putative biomarker, correlating with endometrosis and useful in fertility assessment. Thus, COL3 may offer a non-invasive diagnostic tool, as a complement to histopathological methods. Epigenetic modifications and miRNA expressions offer new avenues for therapeutic strategies, emphasizing the importance of understanding the cellular mechanisms at play in mare endometrial fibrosis.

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Equine endometrosis is a degenerative and predominantly fibrotic condition resulting from progressive and irreversible multifactorial causes that influence the endometrium of mare. Tissue remodeling in the equine endometrium occurs as part of the pathogenesis of endometrosis, a process characterized by a shift in extracellular matrix (ECM) components. The relationship between matrix metalloproteinases and their specific inhibitors is crucial for the remodeling process. Collagen play a significant role in maintaining a healthy uterus and may promote fibrotic processes. The aim of this study was to quantify endometrial collagen deposition using picrosirius 25 red (PSR) staining, and to evaluate gene expression of collagen type 2 (COL-2) and 3 (COL-3), matrix metalloproteinases 1 (MMP-1) and 2 (MMP-2), their tissue inhibitor (TIMP-2), and tumor necrosis factor (TNF-α) in the endometrium of mares with different grades of fibrosis. The samples (n = 34) were classified into three categories based on the frequency and distribution of fibrosis-related changes in the endometrium: Category I (healthy endometrium, n = 12), Category II (moderate fibrosis, n = 12), and Category III (severe fibrosis, n = 10). Collagen quantification demonstrate a substantial proportional increase (P < 0.0001) in collagen deposition across Category I (11.72 ± 1.39 %), Category II (17.76 ± 1.29 %), and Category III (24.15 ± 1.87 %). In transcript evaluations, higher COL-2 expression was found in Category II than in mares classified as Category I or III. MMP-1 showed increased transcript expression in Category II compared to Category III endometrial samples. Higher expression of MMP-2 was detected in Category III than in Category I and II. TIMP-2 showed lower mRNA expression in Category III vs Category I and II. However, TNF-α gene expression was higher in Category II than in Categories I and III. This study demonstrates that endometrial evaluation using PSR can play an important role in routine analyses for the detection and objective quantification of collagen in endometrial tissues. Additionally, this study demonstrated through gene expression analysis that MMP-1 may be linked to physiological endometrial remodeling. In contrast, MMP-2 could be associated with fibrogenesis in the endometrium, which is regulated by the inhibitor TIMP-2. Furthermore, COL-2 and TNF-α could be considered as biological markers involved in the progression endometrosis in mares. As such, the results of this study may contribute to the development of future antifibrotic therapies that aim to delay or even reverse the pathological remodeling of the extracellular matrix in the uterus, in addition to optimizing the diagnosis and prognosis of endometrial fibrosis in mares.

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Assisted reproductive technologies (ARTs) are performed worldwide in the equine industry to produce genetically valuable foals. Among them, ovum pick up (OPU) combined with intra-cytoplasmic sperm injection (ICSI) can now be more efficient than embryo transfer (ET) under optimal conditions. However, OPU is not a benign procedure for the mare and the process is costly. Improved efficiency is therefore in the interest of everyone, maximizing mare welfare and optimizing economics for the client. One of the key factors of success is the antral follicle count (AFC) at the time of OPU and subsequently the number of oocytes obtained. Variations in AFC are reported between individuals and between geographical areas. This leads to a significant increase in numbers of embryos produced per session in some countries compared to others, independent of the laboratory efficiency. This article revisits the basics of folliculogenesis involved in establishment of the antral follicle population and explores work in other species given the paucity of equine research in this area. The aim of the review is to elucidate interesting areas of further research that could generate essential information for clinicians and clients about the management and selection of the donor mare for OPU and potentially identify pharmacological targets for manipulation.

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BACKGROUND: The peripartum period constitutes a delicate physiological moment in mares showing a transient state of oxidative stress. Diet supplementation with antioxidants during pregnancy in women appears to have a beneficial effect on mother and neonate health. The aim of this work was to evaluate the effects of diet supplementation with a commercial product containing a mix of antioxidants (Oxyliver®, Candioli) on the length of gestation, weight, and haemato-biochemical parameters in Italian Salernitano mares and their newborn foals. Eight late-term pregnant mares were randomly divided into two groups: Antiox group receiving 30 g/day of antioxidants, and Car group receiving the same amount of carrot powder, from 290 to 320 days of gestation. The following parameters were evaluated in mares: weight, colostrum composition, haemato-biochemical parameters, progesterone, and cortisol blood concentrations, along with blood oxidant/antioxidant status. Assessments were conducted at specific time points: immediately before the start of diet supplementation (T0), 15 days after (T1), at the end of diet supplementation (T2), within 8 h after parturition (T3), and 10 days post-partum (T4). Foal parameters such as weight, haemato-biochemical values, cortisol concentration, and blood oxidative stress variables were assessed within 8 h of birth (TF0) and at 10 days of age (TF1). RESULTS: Pregnancy was shorter in the Antiox group (P < 0.05) compared with the Car group; the foals' weight increase of group Antiox (40%) was higher (P < 0.05) compared to those of the Car group (28.6%). The colostrum of the Antiox group exhibited higher levels of Brix, total solids, protein, nonfat solids, casein, urea, density, free fatty acids, and glucose, while lower levels of fat and lactose were observed compared to the Car group (P < 0.05). Mares' serum albumin at T1 and T3, creatinine, glucose, total proteins, total bilirubin, AST, and ALT at T3 were lower in Antiox than in the Car group. No significant differences were found in foals. CONCLUSIONS: While the limited sample size and the potential variability of evaluated parameters, the observed outcomes suggest that Oxyliver® supplementation in mares might safely decrease gestation length and enhance liver function, thus potentially improving colostrum quality and offspring development.

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In humans' and experimental animals' components of the somatotropic axis, such as growth hormone (GH) and insulin-like growth factor 1 (IGF-1) concentrations, decrease with advancing age. Although there is evidence regarding IGF-1, the effect of age on GH in mares, as well as the relationships between both parameters, have not yet been elucidated. On the other hand, although GH and IGF-1 are related to follicular development, it is unknown if they could be correlated with the circulating concentrations of ovarian steroids in mares, as occurs in other species. The hypothesis of this study was that both GH and IGF-1 could experience physiological changes with advancing age also in mares, and that both GH/IGF-1 could be correlated with oestradiol-17ß (E2) and progesterone (P4), as recorded for other species. Hence, the objective of this study was to evaluate the concentrations of GH, IGF-1, E2, and P4 in mares, according to the different ages. Blood samples were drawn from 56 healthy cyclic Spanish Purebred mares belonging to four different age groups: 6-9 years, 10-13 years, 14-16 years and >16 years. Mares aged 6-9 years and 10-13 years showed higher GH concentrations (P < 0.05) than mares of 14-16 and >16 years; and mares aged 14-16 showed higher GH concentrations (P < 0.05) than >16 years (P < 0.05). Mares aged >16 years showed lower IGF-1 concentrations (P < 0.05) than mares of 6-9, 10-13 and 14-16 years (P < 0.05). The concentrations of E2 and P4 showed no significant differences among different age groups. Both GH and IGF-1 were not correlated with each other or with E2 and P4. The concentrations of E2 and P4 did not change with age. Advancing age leads to a decrease in the activity of the somatotropic axis in physiological cyclic mares, represented by a significant GH reduction, which, however, was ascribed for IGF-1 exclusively to mares over 16 years of age, without alterations in steroid hormone patterns.

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Amnion-derived acellular bioscaffold (ADABP) products demonstrate interesting anti-inflammatory and healing properties which could be beneficial for intrauterine use. The objective of this study was to evaluate the safety of intrauterine injection of ADABP on systemic and uterine health. The study design randomly assigned subjects to one of two groups, control mares (n = 3) which received 3 mL injection of sterile saline in the base of each uterine horn, and treatment mares (n = 9) which received 3 mL of ADABP in the base of one uterine horn and 3 mL injection of sterile saline in the base of the other uterine horn. The leukogram had no significant effect of group and no group by day interaction. The serum biochemistry panel had no effect of group on any of the parameters examined. There were no significant differences in uterine culture or uterine biopsy results. The data suggests intrauterine injection of ADABP has no negative systemic or uterine effects.

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BACKGROUND: Weaning represents one of the most stressful events in the life of a horse, and may have long-term impacts on behaviour. There are a range of approaches used to wean foals from mares, including abrupt and progressive separation methods. There is currently a lack of consensus on how stress and impact are measured. OBJECTIVES: To conduct a scoping review to identify and chart measures of weaning-related stress on the mare and foal. STUDY DESIGN: Scoping review. METHODS: The scoping review was conducted using the PRISMA extension for scoping reviews. Systematic searches were conducted in three scientific databases (CAB abstracts, Medline and Embase). The title, abstract and full text of retrieved studies were reviewed against inclusion and exclusion criteria. Publications that remained after full text review were analysed. Data on study design, population characteristics, weaning method and health and behavioural outcomes were extracted and charted. RESULTS: A total of 366 publications were identified; 22 were retained for inclusion and charting. Eighteen studies reported behavioural measures, four only reported physiological measures and 12/22 studies used a combination of both. Fifteen studies analysed foal behaviour only (15/22), six analysed foals with their dams and one analysed the mare only. Duration of most studies (19/22) was a maximum of 12 months post weaning; three studies continued measurements until the foal age was 3-4 years old. MAIN LIMITATIONS: Limited number of studies available for analysis. CONCLUSIONS: There is significant variation in the current evidence around weaning-related impacts in the mare and foal. This includes variation in how weaning methods and management of mares and foals are described, and very limited research evaluating long-term impacts, or the impact on the mare. This scoping review makes recommendations on how to improve the future evidence base.

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To investigate molecular regulation involved in lactation during pregnancy, this study focused on the transcriptomic profiles of mammary tissue from lactating and non-lactating Mongolian mares at the second month of gestation. A total of 4197 differentially expressed genes were identified by comparing mammary tissues from pregnant mares at two different states, including 1974 differentially expressed genes such as the milk protein-related genes a-s1-casein (CSN1S1), k-casein (CSN3), lactalbumin (LALBA), and lactoferrin (LTF), which were highly expressed in the lactating mares group, and overall, these differentially expressed genes were mainly associated with biological processes such as endoplasmic reticulum protein processing, the Toll-like receptor signaling pathway, steroid biosynthesis, cytokine-cytokine receptor interactions, and amino sugar and nucleotide glycolysis. These findings serve as a foundation for investigating the molecular underpinnings of lactation in pregnant equids.

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OBJECTIVE: To describe the indications for and surgical technique of mastectomy of mares and to describe the outcome of 10 mares that underwent mastectomy in a retrospective case series. ANIMALS: 10 mares having disease of one or both mammary glands. CLINICAL PRESENTATION: Medical records (1995 to 2022) from 2 university teaching hospitals were searched to identify mares that had undergone unilateral or bilateral mastectomy. Data regarding history, signalment, diagnostic tests, preoperative treatment, surgical procedure, and postoperative management were reviewed. Follow-up information was obtained by interviewing the owners by telephone. RESULTS: One (n = 4 mares) or both mammary glands (6 mares) were excised for the following reasons: chronic bacterial mastitis (4), neoplasia (3), lymphangiectasia (1), pythiosis (1), and lymphoid hamartoma (1). None of the mares experienced intraoperative complications. The surgical site was closed primarily in 2 mares and left unsutured in 8 mares. Both sutured wounds developed a seroma, and 1 dehisced. The owners reported that the surgical wound, whether sutured or unsutured, was healed within 3 months. All mares returned to use for their intended purpose, but 3 mares were euthanized 2 to 4 years after surgery due to progression of disease. One mare drowned 1 year after discharge. CLINICAL RELEVANCE: Mastectomy can be an effective treatment for mares suffering from disease of one or both mammary glands when the mare is refractory to medical treatment.

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The aim of this study was to explore alterations in plasma metabolites among mares afflicted with endometritis. Mares were divided into two groups, namely, the equine endometritis group (n = 8) and the healthy control group (n = 8), which included four pregnant and four non-pregnant mares, using a combination of clinical assessment and laboratory confirmation. Plasma samples from both groups of mares were analyzed through untargeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) metabolomics. A total of 28 differentially abundant metabolites were identified by screening and identifying differentially abundant metabolites and analyzing the pathway enrichment of differentially. Ten metabolites were identified as potential biomarkers for the diagnosis of endometritis in mares. Among them, seven exhibited a decrease in the endometritis groups, including hexadecanedioic acid, oleoyl ethanolamide (OEA), [fahydroxy(18:0)]12_13-dihydroxy-9z-octa (12,13-diHOME), deoxycholic acid 3-glucuronide (DCA-3G), 2-oxindole, and (+/-)9-HPODE, and 13(S)-HOTRE. On the other hand, three metabolites, adenosine 5'-monophosphate (AMP), 5-hydroxy-dl-tryptophan (5-HTP), and l-formylkynurenine, demonstrated an increase. These substances primarily participate in the metabolism of tryptophan and linolenic acid, as well as fat and energy. In conclusion, metabolomics revealed differentially abundant metabolite changes in patients with mare endometritis. These specific metabolites can be used as potential biomarkers for the non-invasive diagnosis of mare endometritis.

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The nutritional benefits of mare milk are attracting increasing consumer interest. Limited availability due to low yield poses a challenge for widespread adoption. Although lysine and threonine are often used to enhance protein synthesis and muscle mass in horses, their impact on mare milk yield and nutrient composition remains underexplored. This study investigated the effects of lysine and threonine supplementation on 24 healthy Yili mares, mares at day 30 of lactation, over a 120-day period. The mares were divided into control and three experimental groups (six mares each) under pure grazing conditions. The control group received no amino acid supplementation, while experimental groups received varying daily doses of lysine and threonine: Group I (40 g lysine + 20 g threonine), Group II (60 g lysine + 40 g threonine), and Group III (80 g lysine + 60 g threonine). Supplementation in Group II notably increased milk yield, while Groups I and II showed higher milk fat percentages, and all experimental groups exhibited improved milk protein percentages. Additionally, blood levels of total protein, albumin, triglycerides, and glucose were reduced. Detailed analyses from Group II at peak lactation (day 60) included targeted metabolomics and microbial sequencing of milk, blood, and fecal samples. Amino acid metabolomics assessed amino acid content in mare milk and serum, while 16S rRNA gene sequencing evaluated rectal microbial composition. The results indicated that lysine and threonine supplementation significantly increased levels of threonine and creatine in the blood, and lysine, threonine, glutamine, and alanine in mare milk. Microbial analysis revealed a higher prevalence of certain bacterial families and genera, including Prevotellaceae, p_251_o5, and Rikenellaceae at the family level, and unclassified_p_251_o5, Prevotellaceae_UCG_001, and Rikenellaceae_RC9_gut_group at the genus level. Multi-omics analysis showed positive correlations between specific fecal genera and amino acids in mare milk. For instance, Prevotellaceae_UCG_003, unclassified Bacteroidetes_BS11_gut_group, and Corynebacterium were positively correlated with lysine, while unclassified Prevotellaceae was positively correlated with alanine and threonine, and Unclassified_Bacteroidales_BS11_gut_group was positively correlated with glutamine. In summary, lysine and threonine supplementation in grazing lactating mares enhanced milk production and improved milk protein and fat quality. It is recommended that herders, veterinarians, and technicians consider amino acid content in the diet of lactating mares. The optimal supplementation levels under grazing conditions for Yili horses were determined to be 60 g lysine and 40 g threonine per day. Future research should explore the molecular mechanisms by which these amino acids influence milk protein and lipid synthesis in mare mammary epithelial cells.

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The equine uterus is highly interrogated during estrus prior to breeding and establishing pregnancy. Many studies in mares have been performed during estrus under the influence of high estrogen concentrations, including the equine estrual microbiome. To date, it is unknown how the uterine microbiome of the mare is influenced by cyclicity; while, the equine vaginal microbiome is stable throughout the estrous cycle. We hypothesized that differences would exist between the equine endometrial microbiome of mares in estrus and anestrus. The aim of this study was two-fold: to characterize the resident endometrial microbiome of healthy mares during anestrus and to compare this with estrus. Double-guarded endometrial swabs were taken from healthy mares during estrus (n = 16) and in the following non-breeding season during anestrus (n = 8). Microbial population was identified using 16S rRNA sequencing. Our results suggest that the equine uterine microbiome in estrus has a low diversity and low richness, while during anestrus, a higher diversity and higher richness were seen compared to estrus. Despite this difference, both the estrus and anestrus endometrial microbiome were dominated by Proteobacteria, Firmicutes, and Bacteroidota. The composition of the microbial community between anestrus and estrus was significantly different. This may be explained by the difference in the composition of the endometrial immune milieu based on the stage of the cycle. Further research investigating the function of the equine endometrial microbiome and dynamics changes within the uterine environment is required.

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Background and Aim: Donkey and mare milk have high nutritional and functional values, but their lactic acid bacteria (LAB) content remains poorly studied and undervalued in the Algerian dairy industry. This study aimed to isolate and select LAB strains that produce antimicrobial substances during fermentation and to characterize the probiotic profiles of each extracted strain to indicate their potential for antioxidant and proteolytic activity. Materials and Methods: This study focuses on isolating and identifying lactic acid bacterial strains from 10 Equid-fermented milk samples collected in two regions of El Bayed Wilaya (Algeria). Identification of LAB strains was obtained by 16S rRNA sequencing. The probiotic properties of important strains and their aromatic productivity power are assessed. To evaluate their antibacterial activity against Listeria monocytogenes, Staphylococcus aureus, Chryseobacterium joostei, Pseudomonas aeruginosa, and Escherichia coli, we selected 21 strains. Different induction methods have been used to amplify the antibacterial effects against these pathogenic strains. Results: Among a total of 60 identified strains, 31 had a probiotic profile, and most were catalase-negative. Aromatic productivity power was observed in eight strains: Lactiplantibacillus plantarum, Lactobacillus casei, Lactobacillus paracasei, Weissella confusa, Weissella cibaria, Leuconostoc mesenteroides, Leuconostoc lactis, and Lactobacillus sp1. Conclusion: Our results provide insight into the considerable diversity of LAB present in fermented donkey and mare milk. To meet the expectations of the Algerian dairy industry, it is important that the probiotic skills of the nine selected strains are met. In addition, a significant number of these strains may have important probiotic activity and biotechnological potential.

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Mesenchymal stromal cells (MSCs) have regenerative and immunomodulatory potential and may be used to treat injured tissues. Pregnancy has been associated with increased MSCs in the peripheral circulation in multiple species, but to date, there are no reports on this matter in horses. This study aimed to evaluate the effect of pregnancy on isolation efficiency and proliferation capacity of equine MSCs derived from the peripheral blood (PB) of mares. Venous blood samples were collected at the 11th month of gestation and 1 month after delivery from clinically healthy Arabian mares that presented normal pregnancies. Blood samples were processed for in vitro cellular culture and hormonal and metabolic profiles. MSCs were isolated and characterized by trilineage differentiation potential, immunophenotyping, analyzed by gene sequencing and proliferation assays. The isolation of peripheral blood mononuclear cells (PBMCs) of pregnant mares were associated with higher isolation efficiency and proliferative capacity of MSCs derived from peripheral blood (PB-MSCs) recovered pre-partum than those isolated post-partum. Although fetal gender, parity, 5α-reduced pregnanes, insulin, and cortisol were shown to affect cellular proliferation, individual factors and the small population studied must be considered. This study suggests that PB-MSCs from pregnant mares could be a valuable alternative source of MSCs for therapeutic purposes.

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Lunar mare basalt is recognized as an important in situ resource on the lunar surface. However, the significant compositional variability of lunar mare basalts introduces uncertainties concerning the potential for their use in fabricating fibers and composite materials. This study investigates the impact of different components on the fiber-forming capabilities of mare basalts by simulating the compositions of basalts collected from several well-known lunar missions and then preparing simulated lunar mare basalt fibers. Raman spectroscopy is primarily employed for analysis and characterization, using "peak area normalization" to explore the impact of compositional fluctuations in the simulated lunar mare basalts on the glass network structure. The findings indicate that an increase in the Fe content raises the likelihood of basalt fibers crystallizing. Additionally, Fe3+ is shown to substitute for Si and Al in constructing bridging oxygen bonds in the network structure, albeit reducing the overall polymerization of the network. Meanwhile, Fe2+ acts as a network modifier to enhance the mechanical properties of the fibers.

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The development of innovative ingredients of specialized formula for children with intolerance to cow's milk proteins requires accounting the influence of the protein component on the allergic sensitivity. The aim of the research was to study the effect of lactoferrin (LF) from cow colostrum, cow's milk protein hydrolysate (CMPH) and mare's milk protein hydrolysate (MMPH) on the severity of the systemic anaphylaxis reaction, the levels of specific IgG antibodies and cytokines in rats parenterally sensitized with ovalbumin (OVA). Material and methods. The experiment was carried out on 4 groups of 26 male Wistar rats, which were sensitized intraperitoneally with chicken egg OVA and a systemic anaphylaxis reaction was induced on the day 29 by intravenous administration of a challenge dose of the antigen (6 mg per kg body weight). LF, CMPH and MMPH were introduced into the diet in doses of 1.4-2 g/kg body weight per day (on an average 1.59±0.04, 1.53±0.05 and 1.48±0.05 g per kg body weight respectively). The content of IgG antibodies in the blood serum was determined by an indirect ELISA; the levels of cytokines IL-1α, IL-1ß, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12(p70), IL-13, GM-CSF, IFN-γ and TNF-α were detected by multiplex immunoassay. Results. Dietary LF did not have a significant effect on the severity of active anaphylactic shock (AAS), concentrations of antibodies and cytokines in the blood of animals. As a result of CMPH consumption, there were no significant changes in AAS severity and IgG antibodies to OVA but significant increase in TNF-α level was observed as well as a significant decrease in IL-1α (p<0.05). In animals receiving MMPH, there were also no significant changes in the severity of AAS, but a 1.9-fold decrease in the level of IgG antibodies to OVA (p<0.001) was noticed along with a significant increase in IL-12(p70) (p<0.05) and IL-10 (p<0.10) level. Conclusion. Cosumption of LF by sensitized rats didn't significantly affect their anaphylactic sensitivity and cytokine profile, while CMPH intake induced some signs of pro-inflammatory processes. Consumption of MMPH was accompanied by the formation of an anti-inflammatory cytokine profile, which corresponds to a decrease in the intensity of the humoral immune response to the model allergen. Differences in the effects of two hydrolisates, which have similar degrees of hydrolysis, may be associated with the specific composition of glycopeptides formed during the enzymatic cleavage of milk protein produced by these two species of dairy animals.

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Background and Aim: A combined microbial and cytological examination of uterine samples is the main diagnostic method for endometritis in mares. This study aimed to describe a procedure for using the same uterine cytobrush (CB) for both bacteriological and cytological evaluation. Material and Methods: The procedure consists of rolling the CB onto a sterilized glass slide immediately after collection and before the transfer into a sterile saline solution. In Experiment 1, a comparison between bacteriological results of the cotton swab (CS) and CB or pellet was made in 10 mares; in Experiment 2, bacteriological and cytological results were compared between different processing methods of CB in 28 mares; in other 6 mares, a CB was processed for cytology only, to investigate the reasons for the low cellularity of the pellet. Results: The agreement between culture results from the CB and CS was evaluated, and a comparison between the cytological data obtained by different processing methods of CB was performed. The perfect agreement between the CB and CS microbiological results was found. The described procedure enables useful diagnostic smears for cytology. Moreover, the seeding of both the tip of CB and the saline solution used for the transport produced accurate bacteriological results. Conclusion: The protocol described in this study for the use of CB for both cytological and bacteriological analysis could be used for the diagnosis of endometritis. To maximize diagnostic sample quality, cytology slides must be prepared with meticulous care in the field to preserve cellular integrity and minimize artifacts.

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BACKGROUND: Peritoneal fluid lactate concentration is an important diagnostic tool in horses with abdominal pain. Information on peritoneal lactate concentrations is lacking following parturition in the mare. OBJECTIVES: To compare blood and peritoneal lactate concentrations in a population of mares within 36 h post-partum, report a normal reference range and identify any impact of retained foetal membranes (RFMs). METHODS: This is a retrospective study evaluating healthy mares from which blood and peritoneal samples had been obtained within 36 h of parturition. Exclusion criteria included signs of abdominal pain within this period. Data was interrogated for normality using a Shapiro-Wilk test. Wilcoxon signed-rank test and Bland-Altman analysis were used to compare blood and peritoneal lactate concentrations. Linear regression was used to compare age and breed data with peritoneal lactate concentrations. Significance was defined as p < 0.05. RESULTS: Forty mares met the inclusion criteria. Mean age was 12.6 ± 4.1 years, and most mares were multiparous (65%). Peritoneal lactate ((1.2 (IQR = 0.9-1.6) mmol/L) was increased compared to blood lactate concentration (0.7 (IQR = 0-1.1)mmol/L; p < 0.001). Plasma total protein (TP) concentrations were 68 (IQR = 64-74) g/L and peritoneal protein concentrations 8 (IQR = 4-9.7) g/L. Six mares developed RFM. The median fold-increase in peritoneal lactate concentration compared to blood lactate concentration was 0.9 (IQR: 0.01-1.7; range: 0-2.5). The reference range for peritoneal fluid lactate concentration was 0-2.5 mmol/L. CONCLUSION: Peritoneal lactate concentrations in healthy post-partum mares remained within the normal reference range and were not influenced by RFM or parturition. Increased peritoneal lactate in this group warrants further investigation.

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Androgens are produced in both sexes. In females produced by the adrenal gland and the ovaries they play a crucial role in regulating ovarian function, estrogen synthesis and follicular growth. Age leads to a reduction in androgen concentrations, although, at present, these mechanisms are not elucidated in mares. The objective of this study was to evaluate the concentrations of testosterone (T), androstenedione (A4) and dehydroepiandrosterone (DHEA) in mares of different ages. Blood samples were drawn from seventy cyclic Spanish Purebred mares belonging to five age groups: 3-5 years, 6-9 years, 10-13 years, 14-16 years and > 16 years. The concentrations of T, A4 and DHEA were determined by EIA, validated specifically for horses. Mares aged 3-5, 6-9 and 10-13 years had higher T concentrations (P < 0.05) than mares aged >16 years, and mares aged 6-9 years had also higher concentrations than those 14-16 years old (P < 0.05). A4 concentrations were lower (P < 0.05) in mares >16 years old when compared with those of other age groups. DHEA concentrations were lower (P < 0.05) in mares 14-16 years and > 16 years old when compared with those of other age groups. DHEA was positively correlated with T (r = 0.61; P < 0.05) and A4 (r = 0.51; P < 0.05). Age induces reduction in androgens' synthesis in physiologically cyclic Spanish Purebred mares. These physiological variations must be duly considered for a correct and objective interpretation of the analytical data.

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The identification of typical behaviors in stage I of parturition, the opening phase, can be used to improve birth monitoring in the mare. Therefore, this study aimed to comprehensively analyze mare behavior during the opening phase. Real-time recordings of 66 births involving 56 warmblood mares were analyzed using camera footage. Behaviors such as increased locomotor activity, pawing with front hooves, lifting the tail, rolling, kicking with the hind legs toward the abdomen, and looking at the abdomen increased significantly (p < 0.001) in the four hours preceding parturition. Within the last hour of the observation period, a statistically significant change was observed for the duration of lying in the sternal and lateral position (p < 0.001). Significant correlations were observed between parity and the total number of repetitions of lying in the sternal position (p < 0.05). Furthermore, the birth process influenced the repetitions of lying in the lateral position (p < 0.05). These findings indicate distinct behavioral patterns during the opening phase of parturition, which were evident across the observed mares. Nonetheless, notable individual differences were also identified among the mares.