Loss In Mares Research Articles

Comparison of serum amyloid A concentrations in mares with experimentally induced placentitis to normal, pregnant mares using a commercially available, stall-side device

Ascending bacterial placentitis, a significant cause of pregnancy loss in mares, is challenging to diagnose. Diagnostic tools for ascending placentitis include detection of premature mammary development, vulvar discharge, and ultrasonographic changes to the caudal fetal membranes. These tools have limited sensitivity. Changes in serum biomarkers (ie, serum amyloid A, SAA) provide useful, adjunct information for diagnosing placentitis, but point-of-care assays are limited. The goal of this study was to evaluate a quantitative, stall-side test (Stablelab®, Zoetis, NJ, USA) to measure SAA concentrations in plasma from mares with experimentally induced placentitis compared to normal pregnant mares. We hypothesized that SAA concentrations in mares with placentitis would be higher than normal pregnant mares and that changes in SAA would be predictive of placentitis. Placentitis was induced in 12 mares (270-300 days gestation) with trans-cervical deposition of 1 × 107 Streptococcus zooepidemicus directly onto the chorioallantois. Infected mares were randomly assigned to: infected/untreated (UNTREATED; n=6); or infected/firocoxib (FIRO; n=6; administered firocoxib two days prior to infection until abortion/delivery). Gestationally age-matched, normal pregnant mares were assigned to NORM (n=6). Plasma samples were obtained from mares prior to the study (Day 0) and daily until abortion/delivery. Mares from NORM were sampled similarly to infected, gestation-matched mares. Duplicate plasma samples from post-infection Days 0-9, and peripartum, were evaluated for SAA concentrations using a Stablelab® system, permanufacturer's instructions. SAA concentrations from mares were compared between groups (UNTREATED, FIRO, NORM). To normalize distribution, data were log-transformed and groups compared (geometric means ± SE) using a two-sided t-test. Differences were not identified between infected mares (UNTREATED/FIRO), so SAA concentrations from all infected mares were grouped (INFECT; n=12) and compared to NORM (n=6). Significance was set at P < 0.05. SAA concentrations were significantly higher in INFECT than NORM by Day 4 post-infection (17.81µg/mL± 10.44 v. 0.76µg/mL± 0.62) and remained significantly higher through Day 9 post-infection (412.32µg/mL± 306.67 v. 0.40µg/mL± 0.04). Prior to foaling, SAA concentrations for INFECT were significantly greater than NORM at -48h (34.72 µg/mL± 23.07 v. 0.41µg/mL± 0.31); -24h (85.32 µg/mL± 48.09 v. 0.6µg/mL± 0.58); at foaling (130.19 µg/mL± 68.97 v. 0.41µg/mL± 0.31); and 24h after foaling (468.25 µg/mL± 224.15 v. 7.63 µg/mL± 4.95). These data showed that mares with experimentally induced placentitis had higher concentrations of SAA than normal foaling mares, early after infection and prior to foaling. Differences in SAA concentrations were detectable using a commercially available, stall-side product (Stablelab®, Zoetis). Monitoring SAA, with a point-of-care assay, may provide useful, adjunct information for diagnosing bacterial placentitis in mares. Funding: Grayson Jockey Club; Zoetis; Merial; Kentucky Thoroughbred Breeders, University of Florida

Effects of firocoxib, trimethoprim sulfamethoxazole and altrenogest on inflammation and foal survival after administration to mares with experimentally induced placentitis

Bacterial placentitis is a leading cause of pregnancy loss in mares. Infection, inflammation and prostaglandin production induce preterm delivery leading to poor foal survival. Treatment strategies for placentitis that control infection and inhibit inflammation are vital. The goals of this study were: 1. Assess the anti-inflammatory effects of firocoxib, trimethoprim sulfamethoxazole (TMS) and altrenogest administered to mares with placentitis; 2. Determine the efficacy of firocoxib, TMS and altrenogest for improving foal outcome in mares with placentitis. We hypothesized that this treatment would significantly decrease pro-inflammatory mediators in fetal fluids and tissues when compared to untreated, infected mares and would also improve foal survival. Placentitis was induced in 13 pregnant mares (270-300 days gestation; via intracervical inoculum of Streptococcus zooepidemicus). Mares were randomly assigned to: infected/untreated (UNTREATED; n=6); or infected/treated groups (TREATED; n=7; administered firocoxib, TMS, and altrenogest from the onset of clinical signs of placentitis until abortion/delivery). Fetal fluids, membranes and tissue samples were obtained at abortion/delivery for quantification of TNF-α, IL-1β, IL-10, IL-6, IL-8, PGE2, PGF2α, and matrix metalloproteinases (MMP) -1, -3, -9 using ELISA (fluids) and real-time PCR (tissues). P < 0.05 was considered significant. Gestation length and foal survival were significantly higher in TREATED (mean days post-infection = 40; 7/7 live foals) than UNTREATED (mean days post-infection = 14; 2/6 live foals). Administration of firocoxib, TMS andaltrenogest resulted in significantly lower amniotic fluid concentrations of IL-1β, IL-6, PGE2 and PGF2α in TREATED than UNTREATED. Amniotic fluid IL-10 concentration tended (P < 0.1) to be lower in TREATED than UNTREATED. Cytokine and prostaglandin concentrations in allantoic fluid were not different between groups except PGE2 which tended (P < 0.1) to be lower in TREATED than UNTREATED. The relative quantity of cytokine and MMP mRNA expression in fetal membranes and foal tissues (non-survivors) was log-transformed and estimated marginal means determined. Fetal membranes from TREATED had significantly lower mRNA expression for IL-8 and TNFα compared to membranes from UNTREATED. mRNA expression of IL-1β, IL-6 and MMP3 tended (P < 0.1) to be lower in membranes from TREATED than UNTREATED. mRNA expression of IL-1β, IL-8, IL-10, TNFα, MMP1, 3 and 9 were significantly different between fetal membrane sites. In non-surviving foals, IL-8 mRNA expression was significantly lower in liver than lung while MMP3 expression was significantly higher in liver than lung or spleen. These data provide physiologic evidence that administration of firocoxib, TMS and altrenogest to mares with placentitis has broad anti-inflammatory effects and may improve foal survival. Research funding: Grayson Jockey Club Research Foundation; Merial Animal Health; Kentucky Thoroughbred Breeders Association, University of Florida, University of Georgia.

Additional effects using progestins in mares on levels of thyroid hormones and steroids in neonates.

The risk of pregnancy loss in mares leads to the use of exogenous hormones to help pregnancy maintenance. The objective was to evaluate the proportion of thyroid hormones and steroids in neonates, in the following postpartum period, born to mares fed with synthetic progesterone and to verify the existence of a correlation between the level of progesterone between mother and neonate. Twenty-seven mares and their foals were used. The animals were divided into 5 experimental groups: group 1 (control, without hormonal supplementation), group 2 (random samples fed to 120 days of pregnancy with long-term progesterone), group 3 (mares fed with short-term progesterone as of 280.º day of pregnancy), group 4 (mares fed with long-term progesterone as of 280.º day of pregnancy) and group 5 (mares fed with synthetic hormone [altrenogest] as of 280.º day of pregnancy). The animal's blood collection took place immediately after parturition for the hormonal measurement. The hormones measured in neonates were total T3, free T4, TSH, progesterone and cortisone. In mares, only levels of progesterone. The groups of neonates showed no difference on levels of total T3, free T4, TSH and progesterone. There was no difference on levels of progesterone in mares among the groups. Neonates from groups 4 and 5 had higher and lower cortisone levels, respectively. No neonate showed clinical change. There was also no correlation between levels of progesterone in mares and foals. Thus, hormonal supplementation with long-term progesterone as of 280 days of pregnancy leds to an increase in the neonate's cortisone levels, in the meantime, supplementation with altrenogest as of 280 days of pregnancy caused a decrease on cortisone levels in foals, despite clinical signs have not been observed on these animals.

One clone to rule them all: Culture-independent genomics of Chlamydia psittaci from equine and avian hosts in Australia.

Chlamydia psittaci is an avian pathogen with zoonotic potential. In Australia, C. psittaci has been well reported as a cause of reproductive loss in mares which subsequently have been the source of infection and illness in some in-contact humans. To date, molecular typing studies describe the predominant and clonal C. psittaci sequence type (ST)24 strains in horse, psittacine, and human infections. We sought to assess the clonality between ST24 strains and the emergence of equine ST24 with a comprehensive genomics approach. We used culture-independent probe-based and metagenomic whole-genome sequencing to investigate 13 C . psittaci genomes from horses, psittacines, and a pigeon from Australia. Published genomes of 36 C . psittaci strains were also used to contextualise our Australian dataset and investigate lineage diversity. We utilised a single-nucleotide polymorphism (SNP) based clustering and multi-locus sequence typing (MLST) approach. C. psittaci has four major phylogenetic groups (PG1-4) based on core-genome SNP-based phylogeny. PG1 contained clonal global and Australian equine, psittacine, and human ST24 genomes, with a median pairwise SNP distance of 68 SNPs. PG2, PG3, and PG4 had greater genomic diversity, including diverse STs collected from birds, livestock, human, and horse hosts from Europe and North America and a racing pigeon from Australia. We show that the clustering of C. psittaci by MLST was congruent with SNP-based phylogeny. The monophyletic ST24 clade has four major sub-lineages. The genomes of 17 Australian human, equine, and psittacine strains collected between 2008 and 2021 formed the predominant ST24 sub-lineage 1 (emerged circa 1979). Despite a temporal distribution of 13 years, the genomes within sub-lineage 1 had a median pairwise SNP distance of 32 SNPs, suggesting a recent population expansion or potential cross-host transmission. However, two C. psittaci genomes collected in 2015 from Victorian parrots clustered into distinct ST24 sub-lineage 4 (emerged circa 1965) with ovine strain C19/98 from Germany. This work describes a comprehensive phylogenomic characterisation of ST24 and identifies a timeline of potential bird-to-equine spillover events.

Nocardioform placentitis in a sample population of mares foaling in southeastern Pennsylvania and northeastern Maryland in 2020

Nocardioform placentitis (NP) has been associated with mid to late pregnancy loss in mares. To date, disease outbreaks have been described only in central Kentucky, although sporadic, isolated cases have been reported globally. This study describes a series of cases of NP that occurred in a sample population of 299 mares foaling in southeastern Pennsylvania and northeastern Maryland in 2020. These cases coincided with an outbreak of NP that occurred in Kentucky that same year. On farms that reported information on both normal and abnormal foalings, nocardioform organisms/DNA were isolated from 6.3% of placental samples based on aerobic culture and/or PCR. In cases with characteristic gross lesions of the chorion, 41% of cases were positive on aerobic culture and/or PCR. NP was confirmed in 16 mares that had not resided in Kentucky for breeding or any part of gestation. Characteristics of mares confirmed positive for NP, including age, gestation length, and problems during gestation are described. Standardbred mares bred by artificial insemination were less likely to be affected than Thoroughbred mares bred by natural cover. Affected mares had prolonged Stage III labor compared with normal mares. These findings suggest that regional increases in NP may occur outside of Kentucky, potentially in parallel with Kentucky outbreaks.

Supplemental Nicotinic Acid Elevates NAD+ Precursors in the Follicular Fluid of Mares.

Simple SummaryMiscarriage and embryonic death have been associated with a deficiency in NAD+ resulting from a lack of dietary niacin in women and mice. Mares often suffer from high rates of early embryonic loss, but the dietary requirement of niacin in pregnant mares remains unknown. The aim of this study was to determine the effect of supplementing nicotinic acid, a form of niacin often supplemented in horse diets, on the elevation of other NAD+ precursors in the blood and follicular fluid of mares. We orally administered nicotinic acid to mares over consecutive days and collected blood and follicular fluid at the end of the feeding period. The results show that multiple examined NAD+ precursors were elevated in the follicular fluid of mares at the end of the feeding period, which we propose will aid in reducing early embryonic loss in the mare by promoting good quality oocytes.A deficiency in NAD+ has previously been linked with increased occurrences of congenital abnormalities and embryonic death in humans and mice. Early embryonic death is a major factor involved in pregnancy loss in mares, and very little is known regarding the NAD+ requirements for optimum reproductive function in horses. The aim of this study was to determine the effect of supplementing the diet of mares with nicotinic acid (NA) on the composition of NAD+ metabolites in the blood and follicular fluid. Vehicle alone or NA (3 g per os) were administered to seven mares over a minimum of 3 consecutive days during the follicular phase of the oestrous cycle. Blood samples were collected immediately prior to supplemental feeding and follicular fluid aspiration. Follicular fluid was collected from the dominant follicle through transvaginal ultrasound-guided aspiration. Blood and follicular fluid samples were processed and analysed by mass spectrometry. The concentration of nicotinamide mononucleotide (NMN) in the follicular fluid of NA-fed mares was 4-fold greater than that in the corresponding plasma and 10-fold greater than that in the follicular fluid of vehicle-fed mares. The concentrations of NA, nicotinamide (NAM) and nicotinuric acid (NUR) tended to be greater in the follicular fluid of NA-supplemented mares than in the corresponding plasma. The results show that NA supplementation increased the bioavailability of NAD+ precursors in the follicular fluid of the dominant follicle, which is proposed to better promote the maturation of good quality oocytes, especially in older mares.

No increase in pregnancy rate of mares after preovulatory deep uterine horn application of misoprostol

A potential source of fertility loss in mares is oviductal dysfunction, potentially caused by masses or debris in the lumen, that may prevent either sperm from reaching the fertilization site or the embryo from reaching the uterus. Recently a novel therapeutic method leading to increased pregnancy results was described by infusing misoprostol, a synthetic prostaglandin E1, in the uterus of mares with unexplained fertility problems. In this study, we aimed, after examining the compatibility of misoprostol with semen, to evaluate the pregnancy rate after routine preovulatory deep uterine horn application of misoprostol in clinically normal oestrous mares, which were inseminated in the same cycle. In experiment 1, ejaculates of 10 stallions diluted with INRA 96™ were mixed with different concentrations of misoprostol (0.01 mg/mL, 0.001 mg/mL, 0.0001 mg/mL, and 0.00001 mg/mL) and total semen motility was evaluated immediately, 12, 24, 48, and 72 h later, and compared with a control sample (mixed with NaCl 0.9%). In experiments 2 and 3, 33 privately-owned clinically normal oestrous mares were each allocated to a treatment or control group. Ovulation was then induced with intramuscularly 2.25 mg deslorelin acetate. At the moment of ovulation induction (experiment 2) and 24 h earlier (experiment 3), 0.2 mg misoprostol diluted in 2 mL NaCl 0.9% were applied deep in the uterine horn (treatment groups) and pure 2 mL NaCl 0.9% in the mares of the control groups. Mares were then inseminated 24 h after deslorelin administration and prior to ovulation with commercial chilled-warmed or frozen-thawed semen, as well as immediately after ovulation detection (both types of semen) maximally 48 h after ovulation induction. In experiment 1, regardless of time and compared with the control groups, all solutions with different concentrations of misoprostol had a negative effect on total motility of semen, which was significant for the highest concentrations (0.01 mg/mL: 18.0% reduction, CI = 22–13%, p = < 0.01). We found no beneficial effect of preovulatory uterine treatment with misoprostol on pregnancy rate (OR = 0.45, CI = 0.15–1.31, p = 0.14): in experiment 2, 2/11 (18.2%) mares of the treatment group became pregnant vs. 12/22 (54.5%) mares in the control group (OR = 0.19, CI = 0.03–1.06, p = 0.07), in experiment 3, 5/14 (35.7%) mares in the treatment group vs. 7/19 (36.8%) mares in the control group (OR = 0.95, CI = 0.23–4.02, p = 0.95), respectively. In conclusion, pregnancy rate was not increased in reproductively normal mares with routine preovulatory deep uterine horn application of misoprostol.

A Diagnostic Survey of Aborted Equine Fetuses and Stillborn Premature Foals in Denmark.

Background: Loss of pregnancy in mares can have many different causes, including both infectious and non-infectious conditions. Extrapolation of findings from other studies is often uncertain as the significance of each cause varies across regions. Causes of pregnancy loss in mares have never been thoroughly studied in Denmark, so a prospective cross-sectional cohort study targeting the entire Danish population of pregnant mares was performed over a period of 13 months to obtain knowledge of the significance of individual causes. Fifty aborted or prematurely delivered stillborn fetuses were submitted for necropsy and examined by a panel of diagnostic laboratory methods.Results: Overall, a cause of fetal loss was established for 72% of the examined cases. Most cases (62%) were lost due to a non-infectious cause, of which obstruction of the feto-placental blood circulation due to severe torsion of the umbilical cord was most prevalent. Pregnancy loss due to a variety of opportunistic bacteria, including bacteria not previously associated with abortion in mares, accounted for 12%, while equid alphaherpesvirus (EHV) type 1 was the cause of pregnancy loss in 8% of the cases. EHV type 4 and Chlamydiaceae species were identified in some cases, but not regarded as the cause of fetal loss.Conclusion: Umbilical cord torsion was found to be the most prevalent cause of fetal loss in Danish mares, while infectious causes such as EHV type 1 and streptococci only accounted for a minor proportion of the losses. The study highlights the need for defined criteria for establishing an abortion diagnosis in mares, particularly in relation to EHV types 1 and 4.

Nicotinic acid supplementation at a supraphysiological dose increases the bioavailability of NAD+ precursors in mares.

NAD+ deficiency has recently been linked with increased occurrences of congenital abnormalities and embryonic death in human and animal subjects. Early embryonic death is a major component of pregnancy loss in mares and very little is known regarding the requirement for NAD+ in horses. The aim of this study was to quantify NAD+ and its metabolites in the plasma and urine of mares after orally administering an acute dose of nicotinic acid and determine the absorption, metabolism and excretion of this essential precursor for NAD+ biosynthesis. Nicotinic acid (5g per os) was administered to four mares via a dosing syringe. Blood samples were collected at 0, 0.25, 0.5, 1, 2, 4, 6 and 22h, and urine samples were collected at 0, 3, 6 and 22h. The samples were processed and analysed by mass spectrometry. A general additive model was applied to all metabolite concentration values followed by a post-hoc multiple comparisons test. Nicotinic acid was rapidly absorbed into peripheral blood within 15min of administration and the concentrations of nicotinic acid, nicotinamide (NAM), nicotinuric acid, nicotinic acid mononucleotide and nicotinic acid adenine dinucleotide (NaAD) increased significantly in plasma at 30min. The concentrations of NAM, nicotinic acid riboside and NaAD increased significantly in urine at 3h. The levels of NAM and NaAD remained significantly elevated in plasma at 22h, sixfold and ninefold greater, respectively, than the basal levels at 0h. While the extracellular levels of NAD+ in the samples remained undetected, the large, sustained elevation of NaAD levels in plasma indicates that the NAD+ levels were boosted within the cellular compartments. The results show that nicotinic acid supplementation increases the bioavailability of NAD+ precursors in mares, which is proposed to be beneficial during periods of peak NAD+ demand, such as during early embryo development.

Effect of Timing of Postovulatory Insemination Relative to Human Chorionic Gonadotropin/Buserelin Treatment With 1 Straw of Frozen-Thawed Semen on Mare Fertility

The reproductive management of mares for frozen semen artificial insemination (AI) can be costly and labor intensive. Predicting the exact time of ovulation can be challenging even when ovulation-inducing drugs are used. The main objective of this retrospective study was to determine whether there was an effect of interval between examinations to detect ovulation on likelihood of pregnancy and early embryonic loss in mares after postovulatory breeding with a single straw of frozen/thawed semen. The second objective was to determine the efficacy of two different drugs (human chorionic gonadotropin vs. buserelin) for timely induction of ovulation. The length of the interval from penultimate check to ovulation had no significant effect on pregnancy or embryo loss rates (4 hours: 34.1% and 13.3% vs. 8 hours: 26.1% and 0% and 16 hours: 34.5% and 10%, respectively) nor did the ovulation-inducing drug used, number of the cycle, or the stallion. In conclusion, there appears to be no advantage of checking mares for ovulation during the late evening and night hours when using a postovulatory AI protocol and ovulation-inducing drugs.

Uterine responses and equine chorionic gonadotropin concentrations after two intrauterine infusions with kerosene post early fetal loss in mares

Pregnancy loss during the normal lifespan of endometrial cups (∼37-120-150 days of gestation) may affect a mare’s ability to conceive again in the same breeding season, as equine chorionic gonadotropin (eCG) secretion by retained endometrial cups can lead to abnormal ovulations and follicular growth. While intrauterine kerosene infusion has anecdotally been proposed as a treatment for endometrial cup retention, there are no controlled studies evaluating kerosene’s ability to enhance endometrial cup regression following abortion. The objectives of this study were to assess uterine response, systemic side effects, and efficacy of intrauterine kerosene infusions after abortion. We hypothesized that kerosene infusions would hasten regression of endometrial cups without detrimental effects on the endometrium and the mare’s general health. Twelve light-breed mares were enrolled in the study after an experimentally induced abortion with cloprostenol (n = 12) by 60 ± 2 days of gestation. Mares were randomly allocated to receive an intrauterine infusion with 500 mL of kerosene (n = 6) or 500 mL saline (n = 6) on days 21 and 35 after pregnancy termination. Uterine biopsies were collected at days 7, 21, 35, and 49 post-abortion to evaluate the degree of endometrial fibrosis with Picrosirius Red Stain and to be graded according to the Kenney & Doig 1986 classification. Furthermore, histomorphometry analysis of the endometrium lining, glandular epithelium and glandular density was performed. Endometrial lymphocyte B CD20+, lymphocyte T CD3+, and macrophage IBA-1+ cell populations were characterized by immunohistochemistry. Physical examinations, blood cell counts, and serum biochemistry were performed before, and for 2 days after each uterine infusion. Serum samples were collected for assessment of eCG concentrations. Continuous data were analyzed with MIXED procedure with repeated measures in SAS, categorical data with LOGISTIC procedure of SAS. Significance was set at p < 0.05. Kerosene infusion did not affect complete blood cell counts, serum chemistry parameters, or physical examinations. Concentrations of eCG decreased over time (p < 0.001), but there were no differences between groups or time by group interactions (p = 0.72). Histological evaluation of the uterus showed no signs of increased fibrosis or degeneration in the treatment group. In conclusion, while kerosene infusions did not appear to have detrimental effects on mare health, our findings suggest that the use of kerosene in the uterus does not enhance the regression of endometrial cups by 49 days post-abortion.

Hexokinase 2 drives glycogen accumulation in equine endometrium at day 12 of diestrus and pregnancy

BackgroundSecretion of histotroph during the prolonged pre-implantation phase in mares is crucial to pregnancy maintenance, manifested as increased embryonic loss in mares with age-related endometrial degeneration. Glycogen content of uterine histotroph is higher during the progesterone-dominated phase of the estrous cycle in mares, but regulatory mechanisms are not well understood.MethodsmRNA expression of glycogen-metabolizing enzymes (HK1, HK2, GSK3B, GYS1, PEPCK, PKM, PYGM) in endometrial samples were compared among mares in anestrus, estrus, and at Day 12 of diestrus and pregnancy. In addition, hexokinase 2 (HK2) activity was assessed using a colorimetric assay.ResultsHK2 was the key regulator of glycogen accumulation during diestrus and pregnancy; hexokinase transcript abundance and enzyme activity were significantly higher during diestrus and pregnancy than estrus and anestrus. In addition, despite similar relative transcript abundance, hexokinase activity was significantly greater in the pregnant versus diestrous endometrium. Therefore, we inferred there was regulation of hexokinase activity through phosphorylation, in addition to its regulation at the transcriptional level during early pregnancy. Based on immunohistochemistry, HK2 was localized primarily in luminal and glandular epithelial cells, with weaker staining in stromal cells.ConclusionAmong glycogen metabolizing enzymes identified, expression of HK2 was significantly greater during the progesterone-dominated phase of the cycle.

Success rates of various techniques for reduction of twin pregnancy in mares.

Twinning is an important cause of pregnancy loss in mares and is often associated with economic loss. Most twin pregnancies can be expected to result in early gestational death, late-term abortions, or delivery of small foals with retarded growth. These foals can be more susceptible to infections and slower to develop after birth, compared with singletons. 1,2 Abortion in late gestation and the birth of twins often involve dystocia and trauma to the reproductive tract and are associated with poor rebreeding potential. 3 Prior to 1997, reported incidence rates of twinning-associated spontaneous abortion in mares ranged from 112 of 516 (22%) 4 to 689 of 1,788 (38.5%). 5 Results of a 9-year study 6 undertaken between 1988 and 1997 in the United Kingdom have shown that the rate of spontaneous abortion in mares was as low as 75 of 1,252 (6%). Although the direct effect of increased availability of ultrasound scanning on twin-associated spontaneous abortions has not been studied, it is possible that routine early scanning practices have contributed to this reduction. A report in 1973 indicated that only 9 of 62 (15%) twin pregnancies produced 2 live foals and that foals born alive were usually emaciated. 4 In that study, 4 13 of 31 (42%) foals born of twin pregnancies had died by 7 days of age, compared with 15 of 1,665 (0.9%) singleton foals. Mares that give birth to twins are also likely to have an oversized uterus, which delays postpartum involution and has been associated with reduced live foaling rates in subsequent breeding seasons. 1,7 Undetected and unmanaged twin pregnancies have important implications, with negative effects on animal health and economic loss being the principle detriments. Reduction of twin pregnancies without subsequent loss of the remaining foal is particularly important in animals with high economic value, mares with poor subsequent breeding potential, cases where the diagnosis is made late in gestation or late in the breeding season, and situations where a stallion is not available for rebreeding. Twin births in mares can and should be avoided,

Serum amyloid A and haptoglobin concentrations are increased in plasma of mares with ascending placentitis in the absence of changes in peripheral leukocyte counts or fibrinogen concentration.

Currently, placentitis, an important cause of late pregnancy loss in mares, is diagnosed by clinical signs and ultrasonography. Acute phase proteins (APP) are mainly produced and secreted by the liver in response to acute inflammatory stimuli. We hypothesized that APP are increased in mares with placentitis. Concentrations of serum amyloid A (SAA), haptoglobin (Hp), fibrinogen (Fb), and white blood cell counts (WBC) were determined in plasma of mares with experimentally induced placentitis and gestationally age-matched control mares. Placentitis was induced via intracervical inoculation of Streptococcus equi subspecies zooepidemicus, a common isolate from clinical cases of bacterial placentitis. Concentrations of SAA and Hp were also determined in the 10days pre-partum in normal mares. Mares with placentitis aborted within 5-25days after inoculation. Concentrations of SAA and Hp rapidly increased subsequent to experimental induction of placentitis and remained increased until abortion. Neither Fb nor WBC appeared to be useful markers for placentitis. Parturition did not trigger increase in either SAA or Hp in normal foaling mares.

Exposure of mares to processionary caterpillars (Ochrogaster lunifer) in early pregnancy: An additional dimension to equine amnionitis and fetal loss

Equine amnionitis and fetal loss (EAFL) is an unusual form of abortion in mid- to late-gestation mares, first identified in Australia in 2004. It has been shown that both whole processionary caterpillars (Ochrogaster lunifer) and their shed exoskeletons can induce abortion in mares during midgestation. These abortions exhibited gross pathology and bacteriology results consistent with field cases of EAFL. To determine whether exposure of mares to the shed exoskeletons of processionary caterpillars can induce abortion in the preplacentation (<35 days' gestation) and early placentation (45-60 days) stages of pregnancy. In vivo experimental study. Mares less than 35 days' gestation and between 45 and 60 days' gestation were exposed to a slurry of shed processionary caterpillar exoskeletons by nasogastric intubation. Mares were monitored by clinical examination daily. Transrectal ultrasonography was performed daily (control and treated preplacentation mares, treated early placentation mares) or every second day (control early placentation mares). Uterine swabs were collected from mares that aborted. All live foals underwent a clinical examination. Placentas were examined, with sampling for bacteriology and histopathology if appropriate. Abortions occurred in treated mares in both experiments without signs of impending abortion. One mare aborted in the embryonic stage experiment and 2 in the early placentation experiment. Embryonic and fetal death was detected on transrectal ultrasonography prior to abortion. In the early placentation experiment, one foal was born 5 weeks preterm and was very small, with laxity of the tendons in all limbs. Enteric or environmental bacteria, consistent with EAFL, were isolated from the mares that aborted. Focal mucoid placentitis lesions were present on the placentas of 2 treated mares, one from each experiment. Processionary caterpillar exposure may be associated with EAFL-related embryonic and early fetal loss in mares. Processionary caterpillars may also play a role in the occurrence of focal mucoid placentitis.

Factors Influencing the Frequency of Pregnancy Loss among Thoroughbred Mares in Hidaka, Japan

Pregnancy loss in mares is thought to be a main problem associated with reproductive efficiency. To clarify the situation of pregnancy loss in Thoroughbred mares in Japan, the occurrence of pregnancy loss before and after 35 days of gestation was investigated with 1,476 Thoroughbred mares in Hidaka, Japan, from 2007 to 2009. Pregnancy loss on days 17-35 was determined by ultrasound examination between 17 and 35 days after the last mating. Follow-up surveys were conducted between 35 days and foaling to determine pregnancy loss on day 35 until foaling in 843 of these mares. Using multiple logistic regression analysis, we assessed the influence of mare age, reproductive status, twin pregnancy reduction, body condition score (BCS), estrus type in foaling mares (foal heat or not), progesterone therapy, and endometrial cysts on pregnancy loss rates on days 17-35 and on day 35 until foaling in this population of mares. The pregnancy loss rates on days 17-35 and on day 35 until foaling were 5.8% and 8.7%, respectively. The overall pregnancy loss rate (day 17 until foaling, including parturient losses) was 14.7%. Risk factors for pregnancy loss included decrease in BCS between 17 and 35 days, <5 BCS at day 35, mating during foal heat, and endometrial cysts. In all, 14.7% of pregnancies were lost between day 17 and birth, contributing significantly to reduced reproductive efficiency in Thoroughbred mares in Japan. These observations indicate that mares should be maintained at high BCS and should be prevented from mating in foal heat to decrease the pregnancy loss rates.

HORSE SPECIES SYMPOSIUM: A novel approach to monitoring pathogen progression during uterine and placental infection in the mare using bioluminescence imaging technology and lux-modified bacteria1,2

Uterine and placental infections are the leading cause of abortion, stillbirth, and preterm delivery in the mare. Whereas uterine and placental infections in women have been studied extensively, a comprehensive examination of the pathogenic processes leading to this unsatisfactory pregnancy outcome in the mare has yet to be completed. Most information in the literature relating to late-term pregnancy loss in mares is based on retrospective studies of clinical cases submitted for necropsy. Here we report the development and application of a novel approach, whereby transgenically modified bacteria transformed with lux genes of Xenorhabdus luminescens or Photorhabdus luminescens origin and biophotonic imaging are utilized to better understand pathogen-induced preterm birth in late-term pregnant mares. This technology uses highly sensitive bioluminescence imaging camera systems to localize and monitor pathogen progression during tissue invasion by measuring the bioluminescent signatures emitted by the lux-modified pathogens. This method has an important advantage in that it allows for the potential tracking of pathogens in vivo in real time and over time, which was hitherto impossible. Although the application of this technology in domestic animals is in its infancy, investigators were successful in identifying the fetal lungs, sinuses, nares, urinary, and gastrointestinal systems as primary tissues for pathogen invasion after experimental infection of pregnant mares with lux-modified Escherichia coli. It is important that pathogens were not detected in other vital organs, such as the liver, brain, and cardiac system. Such precision in localizing sites of pathogen invasion provides potential application for this novel approach in the development of more targeted therapeutic interventions for pathogen-related diseases in the equine and other domestic species.

Diagnosis and management of twinning in mares

TWIN and triplet births are common in sheep and goats, but multiple births occur less frequently in uniparous species such as cattle and horses. Twinning is an important non-infectious cause...

Equine endometrial fibrosis correlates with 11β-HSD 2, TGF-β 1 and ACE activities

Endometrial periglandular fibrosis (EPF) contributes to embryonic and fetal loss in mares. Equine EPF correlates inversely with conception and successful gestation. In the modified Kenney endometrial biopsy classification system, EPF categories I, IIA, IIB, and III correspond to minimal, mild, moderate, and severe fibrosis (±inflammation), respectively. Paraffin sections of biopsy specimens were stained with H&E, and picrosirius red (specific for fibrillar collagens types I and III), to determine %EPCVF. Endometrial ACE-binding activity, TGF-β 1 and 11β-HSD 2 activities were also measured. Ultrastructural changes in EPF categories IIB and III endometria strongly suggested myofibroblastic transformation. ACE-binding activity was highest in EPF category IIB; however, endometrial TGF-β 1 and 11β-HSD 2 activities were significantly correlated to the severity of EPF ( P < 0.05). We conclude that, locally generated angiotensin II initiates the expression of TGF-β 1 resulting in myofibroblastic transformation. 11β-HSD 2 in concert appears to modulate the severity of endometrial fibrosis.

Progesterone and equine chorionic gonadotropin concentrations around the time of pregnancy loss in mares impregnated by donkeys or stallions

The objective of this study was to compare the incidence of pregnancy loss of mares carrying a mule embryo with that of mares carrying a horse embryo. The possible causes of such mortality were evaluated through serial ultrasonographic evaluations and hormonal monitoring, paying special attention to the role of premature regression of the endometrial cups and its relation to inadequate luteal function. Twenty-eight mares impregnated by stallions and 19 mares impregnated with donkey semen were evaluated ultrasonographically every week from day 20 to day 150 of pregnancy. The viability of the product was assessed each time, and the diameter of the embryonic vesicle was measured from day 25 to day 60. Blood samples for progesterone and equine chorionic gonadotropin (eCG) determination were taken every week. Both progesterone and eCG concentrations during normal pregnancies wegre significantly lower in the mares inseminated with donkey semen than in the mares impregnated by stallions (P<.05). In 7 of the mares carrying mule conceptuses to term, the concentrations of eCG remained basal throughout the study. In the other animals from this group, the levels of this hormone did increase but returned to baseline much earlier (on day 77 of pregnancy) than in the mares served by stallions (on day 126 day of pregnancy). There was no significant difference between the growth rate of embryonic vesicles of mares carrying mule embryos and that of mares carrying horse embryos (P>.05). The incidence of pregnancy loss was significantly higher (P<.05) in mares carrying a mule embryo (36.8 %) than in mares carrying a horse embryo (21.4%); it occurred on average on day 93 of pregnancy in mares carrying mule embryos and on day 43 on mares carrying horse embryos. There was only 1 case in which pregnancy loss was associated with concentrations of both eCG and progesterone that were much lower than the average for the normal pregnancies of the same group, and this was in a mare carrying a horse embryo. The most frequent cause of pregnancy loss was premature luteal regression due to primary luteolysis, as evaluated via peripheral progesterone concentrations. This occurred in 2 mares carrying horse embryos and in 4 mares carrying mule embryos. Three mares carrying mule embryos and 1 carrying a horse embryo had abortions that were not preceded or accompanied by any alteration in progesterone or eCG levels and were thus classified as fetal deaths of non-endocrine origin. It is concluded that the incidence of pregnancy loss is higher in mares carrying a mule embryo than in mares carrying a horse embryo. However, this is not due to the low progesterone concentrations associated with the premature regression of the endometrial cups that occurs in mares with interspecific pregnancy.