Periparturient Mares Research Articles

The Effect of Different Storage Temperatures over Time on the pH of Mammary Gland Secretions in Periparturient Mares.

The objectives of this study were (i) to determine pH and electrolyte concentrations in MGS collected prepartum and at parturition, (ii) to characterize mare milk pH during the first week postpartum, and (iii) to evaluate pre-foaling MGS pH at three storage temperatures. This study outlined two hypotheses: (i) all mares exhibit acidic pH, increased calcium, magnesium, and potassium, and reduced sodium concentrations regardless of prepartum pH and electrolytes; (ii) pre-foaling MGS pH varies with storage temperature and time in an initial value-dependent manner. Twenty-three multiparous mares were monitored daily from 320 days of gestation until parturition. Pre-foaling MGS was collected, and pH was immediately measured using a hand-held pH meter. Aliquots were preserved for further electrolyte analysis. Postpartum, samples from day -7 to 0 (day of foaling) were thawed, and electrolyte concentrations (calcium, magnesium, sodium, potassium) were determined. For the three storage temperatures, pH was measured at 0, 15, 30, 45, and 60 min after storage, and hourly for 10 h post-collection. A range of pH 8 to 6.5 was included to avoid bias towards a specific pH value. The chosen pH groups were 8 (range 7.8-8.2), 7.5 (range 7.3-7.7), 7 (6.7-7.2), and 6.5 (6.2-6.6). Overall, storage temperature affects pH (p < 0.05). In conclusion, this study demonstrated that the majority of the mares had sodium-potassium inversion and acidic pH at foaling. Milk pH is neutral up to four days after foaling, becoming slightly alkaline afterwards, with undetermined clinical significance. The pH of MGS showed minimal variation across storage temperatures, except for pH ~7.5, which increased to ~8 post-storage. This study is the first to address these physiological and practical questions about MGS pH in periparturient mares.

Conductivity of mammary gland secretions is a sensitive and specific predictor of parturition in mares.

Accurate prediction of parturition is paramount to ensuring monitoring of delivery and preventing complications. Assessing the pH and electrolytes of the mammary gland secretions (MGS) helps detect impending parturition. As conductivity is related to electrolyte concentrations and pH, it could be a useful alternative for predicting impending parturition; however, this hypothesis warrants a critical assessment. To assess the ability of conductivity, pH, and Brix in the MGS to predict parturition and to investigate their associations. Field study. The MGS of periparturient mares (n = 241) was assessed daily for conductivity, pH, and Brix index from 320d until parturition. Receiving operating curve cut-off values for conductivity (≤4.8 mS/cm), pH (≤6.4), and Brix index (>23.6%) were used to calculate sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for predicting parturition in ≤24 h. Impending parturition was associated with a reduction in conductivity and pH (p < 0.05), and conductivity was strongly correlated with pH (r = 0.88) and Brix (r = -0.80) (p < 0.05). Sensitivity, specificity, PPV, and NPV for parturition in ≤24 h for conductivity (82%, 91%, 77%, and 92%, respectively), pH (79%, 84%, 81%, and 71%, respectively), and Brix (72%, 79%, 66%, and 83%, respectively) were determined separated and pairwise. Of interest, the sensitivity, specificity, PPV, and NPV, of combining conductivity and pH, were 80%, 95%, 90%, and 88%, respectively. Conductivity (≤4.8 mS/cm) presented the greatest odds ratio for predicting parturition in ≤24 h, and coupling it with pH (≤6.4 pH units) doubled its odds ratio (i.e., 25.4-62.3). Field study. The conductivity of MGS is a sensitive and specific method to predict parturition. This is the first large-scale study showing that a combination of conductivity and pH is useful for predicting parturition in mares. The methods employed can likely apply to other settings with similar results.

Mammary gland secretions’ conductivity alone or coupled with pH as a novel and accurate predictor of foaling and its association with electrolytes

Accurate prediction of parturition is paramount to providing assisted delivery and preventing foaling-induced complications. Assessment of pH and electrolyte concentrations of mammary gland secretions (MGS) are useful to detect impending parturition. The study's hypothesis was that changes in electrolytes and pH alter the conductivity of MGS, thus conductivity could be a more accurate foaling predictor than pH and electrolytes alone. In experiment 1, periparturient mares (n=23) had MGS assessed daily for pH, conductivity, and electrolytes (Ca2+, Na+, and K+) using bench-top analyzers (LAQUA-Twin D 771, Horiba LTDA, Kyoto Japan for pH and conductivity; and Hitachi 911 Roche Diagnostics, Basel Switzerland for electrolytes) and portable handheld devices. Handheld devices (LAQUA-Twin, Horiba) were also compared with bench top analyzers. Mixed-model analyses revealed significant reductions in pH, conductivity, Na+, and increases in Ca2+, and K+ upon impending parturition. Bland-Altman analyses showed no significant deviation from linearity for all devices. In experiment 2, periparturient mares (n=114) had daily MGS assessed for conductivity, pH, and electrolytes using hand-held devices (Laqua-Twin).Mixed-model analyses showed effects of time (P<0.05), but no effect of group (P>0.05) or interaction (group*time) (P>0.05) for all analytes. Conductivity was strongly associated with pH (r=0.90), and moderately associated with Na+ (r=0.77), Ca2+ (r= -0.60), and K+ (r= -0.70). Analyses of receiver operating characteristic (ROC) were performed to determine the cut offs for foaling in 24 h for all analytes; and then the cut off values were used to calculate the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). The results were: conductivity for sensitivity, specificity, PPV, and NPV (0.82, 0.80, 0.82, and 0.60), pH (0.80,0.78,0.81, and 0.70), Ca2+(0.92,0.35,0.68, and 0.76), Na+ (0.65,0.28,0.53, and 0.39), and K+ (0.67,0.25,0.50,0.41). The sensitivity, specificity, PPV, and NPV, for conductivity coupled with pH, were 0.84,0.85, 0.81, and 0.90 respectively. In conclusion, the handheld devices tested herein are as accurate as bench-top analyzers for pH, conductivity, and electrolytes. The conductivity of MGS showed similar results to pH to predict of foaling, and the combination of pH and conductivity enhanced the prediction of parturition in mares.

Colostrum quality associations with passive immunity transfer in foals

The equine epitheliochorial placentation precludes the transfer of passive immunity (TPI) from the mare to the fetus; thus colostrum serves as the sole source of TPI. Colostrum assessment at foaling with a Brix-refractometer is the primary method used in practice to determine colostrum quality and its potential for a complete TPI (>800mg/dL); however, guidelines have not been critically established. In addition, with new tools to monitor mammary gland secretions to detect impending foaling (e.g. handheld pH and conductivity devices), it would be helpful to determine if those devices can add value to the colostrum evaluation at foaling. The objectives of this study were to determine whether pH, conductivity, and Brix-index at foaling can be used to predict the TPI. One-hundred and fourteen periparturient mares had colostrum assessed at foaling for pH, conductivity, and Brix-refractometer (Laqua-Twin-Horiba, Japan). Foaling was assisted and time to stand and time to nurse were recorded. At 24h post-foaling, foals had a complete blood cell count performed, and TPI was assessed using a commercial analyzer (ARS, Foal-IgG-analyzer). Foals were grouped based on IgG concentrations as complete-TPI (i.e., ≥800 mg/dL) and failure (i.e., <800 mg/dL). Data were assessed for normality with Shapiro-Wilk's test and multiple logistic regression. The cutoff values for the Brix-index (>24.4 %), conductivity (<4.5), and pH (<6.4) were determined by ROC. The sensitivity, specificity, positive predictive value (PPP), andnegative predictive value (NPV) for the Brix-index, conductivity, and pH of the colostrum at foaling were calculated to predict the TPI. Of all foals, 74.5 % (85/114) had complete TPI, and 25.4% (29/114) failed. Foals with full-TPI had IgG (1912±278.1mg/dL) four-fold greater than those failing (480.4±260.6mg/dL P<0.0001); their Brix-indexes were 26.5±4.3 vs. 21.4±5.9 (P=0.0007), respectively. The conductivity and pH differed between complete- and failed-TPI (Conductivity 4.4±0.6 vs. 5.4±1 1.7 P=0.007, respectively; pH 6.2±0.2 vs. 6.5±0.4, P=0.02, respectively). There were strong associations between conductivity and pH (r=0.87) and a negative and strong correlation between pH, conductivity, and the Brix-index (r=-0.87; r=-0.78). The IgG was moderately correlated with RBC (r=0.70) and the Brix-index (r=0.71). Sensitivity, specificity, PPP, and NPV of the Brix-index, conductivity, and pH of colostrum at foaling to predict the TPI were 0.80, 0.76,0.95, 0.38; 0.77,0.71,0.93,0.38, and 0.75,0.37,0.71, and 0.42, respectively. TPI of Brix-index coupled with conductivity or pH presented a sensitivity, specificity, PPP, and NPV of 0.85,0.60,0.89,0.40 P=0.02, and 0.83,0.50,0.89,0.37 P=0.0.1, respectively. Combining conductivity and pH resulted in a sensitivity 0.91, specificity 0.91, PPP 0.33, and NPV 0.33. In conclusion, colostrum's Brix-index, pH, and conductivity are closely linked with TPI in foals; ROC-values could indicate if a foal could benefit from colostrum supplementation or hyperimmune plasma administration.

Increase of skin temperature prior to parturition in mares

Prediction of impending foaling is highly desirable as early intervention may improve mare and foal outcomes. However, monitoring the peripartum mare is a time-consuming challenge for breeders and many foaling prediction systems have limitations. “Heating up” of the mare is empirically used by breeders as a sign of upcoming parturition in mares. The purpose of this study was to investigate if an increase in skin temperature shortly before parturition is detectable and to determine whether such physiological changes could be an additional valuable parameter to predict foaling. For that, 56 foalings of 14 Warmblood mares, 5 Arabian mares, 27 Thoroughbred mares, and 2 mares of other breeds were analyzed in this 2-year-study. Eight mares were monitored in both years. Mares were between 4 and 22 years old (average: 10 ± 5.5 years) and the mean pregnancy length was 342 days (±9 days), resulting in 14 births from primiparous mares and 42 multiparous mares. For monitoring the periparturient mares, the Piavet® system (Piavita AG, Zurich, Switzerland) was fixed daily when the mares had returned from the field between 4:00 and 6:00 p.m. and collected the next morning between 6:30 and 7:30 a.m. until the time of foaling. Nocturnal rhythms of the skin temperature with the highest values at the start of measurements and a nadir at 6:00 a.m. were observed. On the foaling night, we found a rise in skin temperature starting on average around 90 min prepartum. Skin temperatures recorded at 50 min before parturition and at each 5 min time point until rupture of the allantochorion were significantly higher (p < 0.05) than the mean temperatures measured in the 5 nights before parturition at the same time, reaching a difference of approximately 0.5 °C. There was a significant effect of parity (p = 0.04) on skin temperature during the last hours before foaling where primiparous mares showed a higher mean temperature than uni- or pluriparous mares as early as from 180 min on before parturition. In conclusion, our study shows an increase in skin temperature in most mares within 90 min before birth. Using new biomechanical and digital technologies, this finding could generate an additional potential parameter for the detection of impending parturition. However, skin temperature cannot be used as the only predictive diagnostic of impending parturition in the absence of other parameters.

Energy and mineral metabolism of peripartum mares and foals of the Quarter Horse breed.

Several studies have demonstrated variations in peripartum blood biochemical analytes used to monitor the health status of mares and their foals of different breeds. We aimed to characterize the physiologic changes of peripartum energy and mineral metabolism in healthy Quarter Horse mares and their neonatal foals. Blood samples were initially collected from 17 mares on days 60 and 30 prepartum, and from mares and their foals on the day of parturition (after colostrum ingestion), and on days 15, 30, and 60 postpartum. The serum concentrations of calcium, phosphorus, magnesium, total cholesterol (T-Cho), triglyceride, beta-hydroxybutyrate (BHBA), and nonesterified fatty acids (NEFA) were measured using commercial kits. Statistical differences were analyzed using one-way ANOVA followed by Tukey's test (parametric variables) or the Kruskal-Wallis test followed by Dunn's multiple comparison test (nonparametric variables). Fourteen of 17 healthy Quarter Horse mares and their neonatal foals remained in the study until termination. Serum BHBA, T-Cho, and calcium concentrations in mares showed significant differences during the observation period. Serum BHBA concentrations increased from 60days prepartum to 60days postpartum. Postpartum serum T-Cho and calcium concentrations significantly decreased until day-30 postpartum. In the foals, NEFA, T-Cho, calcium, and magnesium concentrations significantly differed between sampling times. In the foals, serum NEFA concentrations decreased from parturition until day-60 postpartum, while serum T-Cho, calcium, and magnesium concentrations were lowest at day-30 postpartum. The temporal changes observed in the blood biochemical analytes of this study could be used to improve the clinical evaluation of periparturient mare and neonatal foal Quarter Horses.

Physiological Correlation between Hypothalamic-Pituitary-Adrenal Axis, Leptin, UCP1 and Lipid Panel in Mares during Late Pregnancy and Early Postpartum Period.

Simple SummarySeveral features of periparturient mares’ physiology have been investigated; however, the possible linkage between HPA axis, leptin, and lipid metabolism in periparturient mares has received little attention. Therefore, the present study aimed to investigate the dynamic changes of adrenocorticotrophic hormone, cortisol, leptin, UCP1, lipids and liproteins levels in mares during late pregnancy and the postpartum period. The findings obtained in the current survey showed a dynamic modulation of studied parameters, namely the response to hormonal and metabolic adaptations, occurring during the peripartum period in mares. This study suggests an interaction of the HPA axis with lipid metabolism in mares, probably to deal with the metabolic load occurring during pregnancy and with lactation energy supplies.This study aimed to investigate the dynamic change of adrenocorticotrophic hormone (ACTH), cortisol, leptin, mitochondrial uncoupling protein 1 (UCP1), lipids and lipoproteins in mares during late pregnancy and the postpartum period. A total of 20 mares (10 pregnant mares, monitored from 14 ± 2 days before expected foaling until 14 days after foaling, Group A; 10 non-pregnant and non-lactating mares, Group B) were enrolled in the study. Body Condition Score (BCS) and body weight (BW) values were recorded from each animal. In Group A, blood samples were collected on days 14 ± 2 and 7 ± 2 before foaling (T−14; T−7), and on days 7 and 14 after foaling (T+7; T+14). From mares of Group B, blood samples were collected at the beginning of the study. The levels of ACTH, cortisol, leptin, UCP1, non-esterified fatty acids (NEFAs), total cholesterol, high-density lipoproteins (HDLs), low-density lipoproteins (LDLs), triglycerides and very-low-density lipoproteins (VLDLs) were investigated. While BCS showed no statistical change throughout the monitoring period (p > 0.05), all the other studied parameters displayed statistically significant variations in Group A over the peripartum period (p < 0.0001). A significant effect of pregnancy was found on all studied parameters (p < 0.001). The ACTH and cortisol levels measured in mares belonged to Group A showed a significant positive correlation with the values of leptin, LDLs, triglycerides and VLDLs, whereas they were negatively correlated with the serum UCP1 and NEFAs values. Together, the findings gathered in this study highlight a dynamic change of serum leptin, UCP1 and lipid parameters in peripartum mares and suggest an interaction of the HPA axis with lipid metabolism and mobilization in mares during the peripartum period in order to deal with metabolic and energy demand and maintain energy homeostasis.

A longitudinal study of the faecal microbiome and metabolome of periparturient mares.

BackgroundPeriparturient mares are at increased risk of colic including large colon volvulus, which has a high mortality rate. Alterations in colonic microbiota related to either physiological or management changes, or both, that occur at this time have been suggested as potential causes for increased colic risk in this population of horses. Although the effect of management changes on the horse faecal microbiota has been investigated, limited work has been conducted to investigate changes in faecal microbiota structure and function in the periparturient period. The objectives of the current study were to investigate temporal stability of the faecal microbiota and volatile organic compounds (VOCs) of the faecal metabolome in periparturient mares.MethodsFaecal samples were collected weekly from five pregnant mares from 3 weeks pre-foaling to 7 weeks post-foaling. The microbiome data was generated by PCR amplification and sequencing of the V1–V2 regions of the bacterial 16S rRNA genes, while the VOC profile was characterised using headspace solid phase microextraction gas chromatography mass spectrometry.ResultsThe mare faecal microbiota was relatively stable over the periparturient period and most variation was associated with individual mares. A small number of operational taxonomic units were found to be significantly differentially abundant between samples collected before and after foaling. A total of 98 VOCs were identified. The total number of VOCs did not vary significantly between individual mares, weeks of sample collection and feeds available to the mares. Three VOCs (decane, 2-pentylfuran, and oct-2-ene) showed significant increase overtime on linear mixed effects modelling analysis. These results suggest that the mare faecal microbiota is structurally and functionally stable during the periparturient period. The findings also suggest that if changes in the gut microbiota are related to development of colic postpartum, altered risk may be due to inherent differences between individual mares. VOCs offer a cost-effective means of looking at the functional changes in the microbiome and warrant further investigation in mares at risk of colic.

Evaluation of the oxidative status of periparturient mares supplemented with high amount of α-tocopherol

Aim of the study was to investigate the oxidative status during peripartum period in mares fed high amount of dietary α-tocopherol. α-Tocopherol, ferric reducing ability of plasma (FRAP) and reactive oxygen metabolites (d-ROMs) levels were measured in blood samples from 17 Thoroughbred mares at three intervals: (1) 20 days before the expected foaling date; (2) 12 h following parturition; (3) 7 days post-partum. The levels of α-tocopherol, d-ROMs and FRAP were retrospectively analysed in relation to the number of insemination services (Ins) after foaling performed per conception. The parameters α-tocopherol and d-ROMs evidenced minimal fluctuations during peripartum period while FRAP levels showed a linear decrease. The α-tocopherol did not show significant variations and was numerically higher in mares >10 years old while FRAP levels were significantly higher in older mares in the post-partum. Mares receiving three natural insemination services showed higher levels of FRAP in the pre-partum period (p = .009) and lower values of α-tocopherol (p = .015) in the postpartum compared to mares receiving one service. No d-ROMs level differences appeared among service classes. Oxidative stress is not present in periparturient mares fed 2.750 IU of supplementary α-tocopherol. Differences in redox metabolism are detectable between young and old mares. Plasma antioxidant potential is higher in older mares particularly in the post-partum period.HighlightsOxidative stress is not present in periparturient mares fed 2.750 IU of supplementary α-tocopherol.Antioxidant potential of plasma is higher in mares older than 10 years compared to younger mares.The increased plasma antioxidant potential seems related to an increase in services per conception.

Clinical signs in late pregnant mares

During the peripartal period, interpretation of basic clinical signs may be challenging. In the present study, heart rate (HR), respiratory rate (RR) and body temperature (BT) were evaluated in healthy mares of different breed types and compared to reference values for adult horses from the literature. During daily physical exams of periparturient mares, the HR, RR and BT were evaluated. Differences according to the horse's size were investigated and in large breeds, the influence of dystocia or retained placenta was analysed. During the last weeks before parturition (a. p.), the HR significantly increased and was clearly lower after parturition (p. p.; p < 0.05). In larger horses, the RR increased a. p. and decreased p. p. (p < 0.05). The BT underwent changes in all groups during the periparturient period and was higher p. p. (p < 0.05). In general, values for HR, RR and BT were highest in ponies (p < 0.05) while the lowest RR was measured in large horses (p < 0.05). There was no difference in the HR between mares with eutocia or with dystocia (p > 0.05). By contrast, the RR was significantly higher in mares with dystocia on day 1 p. p. (p < 0.05). Differences in the BT a. p. and p. p. occurred only in mares with eutocia (p < 0.05) and remained within the normal values. Mares with retained placenta did not exhibit significant changes in the HR (p > 0.05), but the BT was higher on day 1 p. p. (p < 0.05). Increased HR, RR and BT in mares during late pregnancy suggest a distinct physical performance for a prolonged period of time. Interpretation of these parameters in relation to the mare's reproductive state is essential to diagnose potential disorders and to determine whether therapy is required.

Effect of density and relative aggressiveness on agonistic and affiliative interactions in a newly formed group of horses

Abstract Group housing provides horses with social contact, a lack of which is associated with health and behavior problems. Despite the benefits of group housing for horses, horse owners are concerned about aggression and resulting injuries. This study focused on agonistic and affiliative interactions in a focal group of (originally) 12 horses with short-term and longer term changes in composition, variation in available area, and presence of periparturient mares. Age and density had no significant effect on agonistic or affiliative behavior. However, when agonistic behavior was considered within 3 subcategories, density did have a significant positive effect on contact and threat aggression but not on passive aggression (avoid and displace). When analyzing only the days without the most aggressive horse, age and density had a positive effect on agonistic interactions, and density had a negative effect on affiliative interactions. Days with and without the most aggressive horse showed no significant overall differences in either category of social interactions. Agonistic and affiliative interactions were not significantly correlated, but agonistic interactions had a significant linear and quadratic effect on affiliative interactions. Relative level of aggressiveness was used instead of a formal measure of dominance rank as aggression level is the main issue for horse owners. Comparing interactions with more and less aggressive horses, there was no overall effect for affiliative interactions. However, overall, horses in the focal group were on average 3.7 times more aggressive toward less aggressive horses, compared to more aggressive horses. Relationships between agonistic and affiliative interactions, density, age, and the role of relative aggressiveness are complicated, and more research is needed to clarify the most relevant factors under particular sets of circumstances and their contribution to intraspecific aggression in various contexts.

Changes of biochemical environment and body weight in healthy periparturient Lipizzan mares

The aims of this study were to determine the concentrations of calcium, magnesium, phosphorus, chlorine, potassium, sodium, urea, total cholesterol, triacylglycerols, non-esterified fatty acids, total protein, creatinine, total bilirubin, aspartate aminotransferase, insulin, insulin growth factor 1, and glucose in the blood serum and to monitor the body weight changes in nine clinically healthy Lipizzan mares at weekly intervals within 2 weeks before and 2 weeks after the parturition. A significant body weight loss (P &lt; 0.01) was found in the mares after the foaling. The peak of insulin growth factor 1 concentration in serum was reached at the day of parturition and similar patterns were revealed for the concentrations of insulin and glucose. After parturition, all these indices were significantly decreased. The concentrations of phosphorus and triacylglycerols were decreased, while the concentrations of potassium and sodium were increased at the day of parturition. Moreover, the concentration of non-esterified fatty acids was increased at the day of parturition (P &lt; 0.05) with a tendency to higher values even on the 7th day postpartum. Other studied indexes remained relatively stable throughout the transition period. We can conclude that periparturient mares face some degree of negative energy balance with concomitant significant homeostatic and homeorhetic changes. For this reason, our results can be used as a basis for reference values and a diagnostic tool to examine the health status in horses during the transition period.

Progestin withdrawal at parturition in the mare.

Mammalian pregnancies need progestogenic support and birth requires progestin withdrawal. The absence of progesterone in pregnant mares, and the progestogenic bioactivity of 5α-dihydroprogesterone (DHP), led us to reexamine progestin withdrawal at foaling. Systemic pregnane concentrations (DHP, allopregnanolone, pregnenolone, 5α-pregnane-3β, 20α-diol (3β,20αDHP), 20α-hydroxy-5α-dihydroprogesterone (20αDHP)) and progesterone) were monitored in mares for 10days before foaling (n=7) by liquid chromatography-mass spectrometry. The biopotency of dominant metabolites was assessed using luciferase reporter assays. Stable transfected Chinese hamster ovarian cells expressing the equine progesterone receptor (ePGR) were transfected with an MMTV-luciferase expression plasmid responsive to steroid agonists. Cells were incubated with increasing concentrations (0-100nM) of progesterone, 20αDHP and 3α,20βDHP. The concentrations of circulating pregnanes in periparturient mares were (highest to lowest) 3α,20βDHP and 20αDHP (800-400ng/mL respectively), DHP and allopregnanolone (90 and 30ng/mL respectively), and pregnenolone and progesterone (4-2ng/mL). Concentrations of all measured pregnanes declined on average by 50% from prepartum peaks to the day before foaling. Maximum activation of the ePGR by progesterone occurred at 30nM; 20αDHP and 3α,20βDHP were significantly less biopotent. At prepartum concentrations, both 20αDHP and 3α,20βDHP exhibited significant ePGR activation. Progestogenic support of pregnancy declines from 3 to 5days before foaling. Prepartum peak concentrations indicate that DHP is the major progestin, but other pregnanes like 20αDHP are present in sufficient concentrations to play a physiological role in the absence of DHP. The authors conclude that progestin withdrawal associated with parturition in mares involves cessation of pregnane synthesis by the placenta.

Leukocyte modifications during the first month after foaling in mares and their newborn foals.

During early post-partum period both neonatal foals and peripartum mares are most susceptible to diseases. The aim of this study was to establish physiologic modifications of leukogram during the first month after foaling in mares and their newborn foals. To this end blood samples were collected from nine mares and nine foals (T0-T10), every three days from the 1st day until the 30th day after foaling. Samples were analysed for white blood cell (WBC) count and differential leucocyte counts. Two-way repeated measure analysis of variance (ANOVA) showed, in postpartum mares WBC showed significant higher values at T0 (9.02±0.76) in respect to other time points, and at T2 (8.08±0.53) and T3 (7.92±0.59) compared to T1 (6.98±0.43), whereas in foals lower WBC values at T0 (6.11±0.49) compared to other experimental periods except T1 (6.90±0.94), and at T1 compared to T8 (7.95±0.61) and T10 (7.90±0.36) were observed. The differential leucocyte counts showed significant modifications in the percentage of neutrophils (π<0.001) and lymphocytes (p<0.001) both in postpartum mares and in foals during the experimental period. Furthermore ANOVA showed significant differences between postpartum mares and foals (P<0.01) in all studied parameters, and between postpartum mares and control mares in WBC and neutrophils values. The obtained results provide suitable information about the influence of foaling on leukogram of periparturient mares and reveal WBC dynamics in newborn foals during the first month post-partum.

Increased serum nonesterified fatty acid and low ionised calcium concentrations are associated with post partum colic in mares.

Increased serum nonesterified fatty acids (NEFA) and decreased serum electrolytes are linked to abdomasal displacements in post partum dairy cattle. Post partum colic in mares may be associated with metabolic changes specific to pregnancy and the periparturient period. To determine if fluctuations in serum NEFA, ionised calcium (iCa) and magnesium (iMg) occurred in periparturient mares and if these alterations were associated with post partum colic. Longitudinal observational study. Mares from 3 farms in central Kentucky were enrolled. Blood samples were collected 14 days prior to the estimated foaling date, within 4 days post parturition, and 14 and 28 days after foaling for batch analysis of serum NEFA, iCa and iMg. Health information was provided by farm managers and veterinarians. Data were analysed using Kruskal-Wallis χ(2) statistic for nonparametric data and a matched case/control approach. Repeated measures logistic regression models were developed. Serum NEFAs were higher at 14-1 day before foaling (mean ± s.d., mmol/l), 0.28 ± 0.12, P = 0.04 and from foaling to 4 days after foaling, 0.29 ± 0.20 (P = 0.05) in mares that developed colic compared with those that did not colic, 0.19 ± 0.05 and 0.21 ± 0.14, respectively. Ionised calcium was lower at 15-28 days post foaling in mares that showed colic, 1.50 ± 0.17 compared to mares that did not colic, 1.60 ± 0.12, P = 0.02. Risk of colic in post partum mares increased 38% for each 0.1 mmol/l increase in serum NEFA (odds ratio = 1.38, 95% confidence interval 1.06-1.81, P = 0.02). Mares with post partum colic had significantly higher serum NEFA and lower iCa prior to the colic episode compared with mares that did not develop colic. Monitoring these metabolic alterations may lead to predictive and preventive colic strategies for post partum mares.

Physiological adjustments of haematological profile during the last trimester of pregnancy and the early post partum period in mares

The aim of the study was to assess changes in some haematological parameters of periparturient mares from the last three months of pregnancy until the third week after foaling. The study was carried out on 15 healthy pregnant mares (Group A) and 7 healthy non-pregnant non-lactating mares (Group B). Blood samples were collected by jugular venipuncture into EDTA tubes and tested for Haematocrit (Hct), Red Blood Cell (RBC), Haemoglobin (Hb), Platelets (Plt) and White Blood Cell (WBC). Peripheral blood smears were also performed to assess changes in the leucocyte differential count. Group A showed a progressive reduction in Hct and Hb levels over the experimental period, whereas Plt and WBC (P<0.05) peaked at parturition. Among WBC, neutrophils increased until parturition when lymphocytes reached the lowest values. The statistical analysis also revealed significant interactions time×pregnancy on Hb (P<0.001), WBC (P<0.001), neutrophils (P<0.001) and lymphocytes (P<0.001). Analysing the last trimester of pregnancy and the first post partum period the present study provides suitable information about the influence of peripartum on mares’ haematological parameters.

Hemostatic profile during late pregnancy and early postpartum period in mares

Hemostasis is a physiological process that prevents excessive blood loss and represents a protective mechanism at the time of delivery. Peripartum hemorrhage is a recurring hazardous condition to mare's health; therefore, we aimed to study mares' hemostatic profile to investigate whether physiological adjustments occur during late pregnancy and early postpartum. Fifteen pregnant mares have been monitored from the 34th week of pregnancy until the third week after foaling. Fifteen nonpregnant mares were used as control group. Jugular blood samples were analyzed for platelet count (Plt), prothrombin time (PT), activated partial thromboplastin time (aPTT), and fibrinogen (Fb). Platelet count showed significant changes at foaling (P < 0.05) and a negative correlation (r = −0.968; P = 0.032) with postpartum. Prothrombin time changed (P < 0.05) showing a significant correlation (r = 0.675; P = 0.016) with late pregnancy. Fibrinogen concentrations changed throughout the experimental period (P < 0.0001). The linear regression model revealed a positive correlation (r = 0.9210; P < 0.0001) between Fb and late pregnancy and a negative correlation (r = −0.9583; P = 0.042) between Fb and early postpartum. The shortening in PT recorded in the imminence of parturition along with the increase in Plt and Fb at foaling might reflect a physiological hypercoagulable state that constrains excessive bleeding, enhancing mares' odds of surviving. Our research improves the knowledge about blood coagulation in periparturient mares providing specific information on routine coagulation tests that may support in monitoring mare's hemostatic profile during late pregnancy and early postpartum.

Hematologic and biochemical profiles in Standardbred mares during peripartum

The purposes of this study were to determine physiological changes occurring in hematologic and biochemical parameters in mares between the last month of gestation and the first week after parturition. If a significant change was observed with respect to the reference interval of an adult horse, a further aim of the study was to establish different reference intervals. Blood samples were collected from 62 healthy pregnant Standardbred mares. Seventeen nonpregnant and nonlactating mares were used as a control group. In pregnant mares, blood sampling was conducted every three days from 1 month before the expected foaling date (335 days after the last mating), at parturition, and 7 days after foaling. The barren mares in the control group were sampled once. Results from samples collected 20 and 10 days before parturition, at parturition, and 7 days after were considered in the statistical analysis. A parametric method for all the parameters studied was used to establish reference intervals. Results were compared by repeated measures ANOVA. When significant differences were observed in relation to sampling time, a post hoc analysis was performed (Tukey test). The one-way ANOVA test followed by Dunnett's test was performed to evaluate the presence of a significant difference between each sampling time and the control group. Any significant difference in the blood count parameters at different sampling times was observed by repeated measure ANOVA. Hemoglobin (P < 0.01) and hematocrit (P < 0.01) 7 days after parturition and white blood cell count (P < 0.01) at parturition were significantly different from the control group. Erythrocyte indices and platelet count were within the normal reference intervals as established in the control group. In the biochemical panel, gamma-glutamyltransferase, creatinine, glucose, biliar acids, total protein, albumin-to-globulin ratio, and calcium were significantly different at different sampling times. Moreover, serum concentration of creatine kinase, aspartate aminotransferase, creatinine, blood urea nitrogen, glucose, lactate, total protein, albumin, albumin-to-globulin ratio, calcium, magnesium, sodium, chloride, potassium, and total, direct, and indirect bilirubin was different from that of the control group. Remarkable changes were not observed in alkaline phosphatase, triglyceride, and fibrinogen concentrations. Temporal changes in the hematologic and biochemical parameters observed in the present study in the peripartum and the differences with reference intervals made up for nonpregnant and nonlactating mares could be used to better evaluate the conditions of periparturient mares.

Serum amyloidAconcentration in healthy periparturient mares and mares with ascending placentitis

Placentitis is a prevalent cause of abortion, premature delivery and neonatal death in mares. Early diagnosis is paramount for the survival of the fetus and delivery of a live foal. To determine: 1) Serum amyloid A (SAA) profile in healthy mares during late gestation; 2) if placentitis affects SAA concentrations and 3) the effects of therapy on SAA concentrations and pregnancy outcome in mares with placentitis. In Experiment I, 15 healthy pregnant mares were evaluated from 280 days of gestation to 60 h post partum. In Experiment II, pregnant mares were inoculated intra-cervically with Streptococcus zooepidemicus (Day 280-295) and assigned to control (n = 5) and treatment (n = 9) groups. Treatment was initiated at the onset of clinical signs. Serum amyloid A concentrations were determined prior to inoculation and then weekly until abortion or delivery. Serum amyloid A remained at low concentrations (95% confidence interval [CI]: 3.2-8.1 mg/l) during late gestation followed by a significant increase within 36 h post partum; SAA returned to basal concentrations by 60 h post partum. In Experiment II, SAA significantly increased within 96 ± 56 h of inoculation in control mares followed by abortion. Therapy was effective (P<0.05) in preventing the rise in SAA in 66% (6/9) of mares and only one out of 3 mares with increased SAA aborted. Overall, the incidence of abortion was higher in mares with increased SAA concentrations (75%; 6/8) compared with mares in which SAA remained at baseline concentrations (0/6). Mares with placentitis had significant increased SAA within 96 h post inoculation and concentrations remained increased until abortion in untreated mares. Successful treatment either prevented the rise of SAA concentration or decreased its concentration to baseline concentrations, followed by delivery of a live foal. Serum amyloid A may be used as a prognostic indicator in cases of ascending placentitis in the mare.

Identification of periparturient mare and foal associated predictors of post parturient immunoglobulin A concentrations in Thoroughbred foals

Prior to the start of endogenous production of immunoglobulins (Igs), absorption of maternal Igs is important to protect against pathogens in the early neonatal period. It is possible that mare- or foal-associated factors may influence neonatal IgA concentrations. The temporal relationships among serum and milk IgA concentrations in Thoroughbred mare-foal pairs were explored to determine if periparturient mare- and foal-associated factors contribute to the prediction of foal serum IgA concentrations. Blood and milk samples as well as complete veterinary records, were collected for 84 Thoroughbred mare-foal pairs from one month before to 2 months after parturition. Samples were tested using enzyme-linked immunosorbent assay (ELISA) for concentrations of IgA. Pairwise correlation coefficients were estimated (P < 0.01) and simple linear regression used to investigate unconditional associations between mare IgA levels, mare and foal risk factors and foal serum IgA concentration at 12 h. Backwards, stepwise elimination of nonsignificant factors was used to create a final model. There were significant temporal relationships among mare serum IgA and among colostrum and milk IgA concentrations within mares (P < 0.01). Mare serum IgA concentrations up to one month before parturition were associated with foal serum IgA concentrations at all time points and with colostrum and milk IgA concentrations. Mare serum IgA at -28 days and parity were associated with foal serum IgA concentration at 12 h (P < 0.001). Mare serum IgA concentrations up to 28 days before parturition, together with mare parity, are indicative of neonatal foal serum IgA concentrations. Mare serum and colostrum IgA concentrations may be useful peripartum predictors of neonatal mucosal immune status, enabling earlier intervention to prevent the consequences of mucosal infections.