Placental abnormalities associated with Leptospira interrogans infection in naturally infected mares.

The reproductive features of equine leptospirosis are often neglected. Equine genital leptospirosis is characterized as a silent chronic syndrome, and besides abortions, leads to placental abnormalities, stillbirths, and birth of weak foals. This study aimed to study the occurrence of placental abnormalities associated with Leptospira interrogans infection in naturally infected mares under field conditions. The studied herd had a high occurrence of placentitis and abortions. Ten pregnant mares, eight with placental abnormalities on ultrasonography and were selected. Serum and cervicovaginal mucus (CVM) samples were collected for serology and PCR, respectively. Positive samples in lipL32-PCR were submitted to the sequencing of the secY gene. In lipL32-PCR of CVM, five out of 10 (50%) mares were positive and all were characterized as Leptospira interrogans. Our results highlight the presence of placental abnormalities in the reproductive subclinical leptospirosis syndrome. We encourage field veterinarians to include leptospirosis testing in their reproductive management.

Characterization of the equine placental microbial population during nocardioform placentitis.

Nocardioform placentitis is a poorly understood disease of equine late gestation. The presence of nocardioform, filamentous branching gram-positive bacteria, has been linked to the disease, with Crossiella equi, Amycolatopsis spp., and Streptomyces spp. being the most frequently identified bacteria. However, these bacteria are not found in all clinical cases in addition to being isolated from healthy, normal postpartum placentas. To better understand this form of placentitis, we analyzed the microbial composition in the equine placenta (chorioallantois) of both healthy postpartum (control; n = 11) and nocardioform-affected samples (n = 22) using 16S rDNA sequencing. We found a lower Shannon index in nocardioform samples, a higher Chao1 index in nocardioform samples, and a difference in beta diversity between control and nocardioform samples (p < 0.05), suggesting the presence of dysbiosis during the disease. In the majority of the NP samples (77 %), one of the following genera-Amycolatopsis, Crossiella, Lentzea, an unidentified member of the Pseudonocardiaceae family, Mycobacterium, or Enterococcus -represented over 70 % of the relative abundance. Overall, the data suggest that a broader spectrum of potential opportunistic pathogens could be involved in nocardioform placentitis, extending beyond the traditionally recognized bacteria, resulting in a similar histomorphological profile.

Infectious Causes of Equine Placentitis and Abortion.

A variety of infectious agents including viral, bacterial, and fungal organisms can cause equine abortion and placentitis. Knowledge of normal anatomy and the common pattern distribution of different infectious agents will assist the practitioner in evaluating the fetus and/or placenta, collecting appropriate samples for further testing, and in some cases, forming a presumptive diagnosis. In all cases, it is recommended to confirm the diagnosis with molecular, serologic, or microbiological testing. If a causative agent can be identified, then appropriate biosecurity and vaccination measures can be instituted on the farm.

Gut microbiota changes in preeclampsia, abnormal placental growth and healthy pregnant women.

BACKGROUND: Preeclampsia (PE) is a condition of high blood pressure that is usually concurrent with proteinuria in pregnancy. PE complicates the management of both maternal and fetal health and contributes to most adverse pregnancy outcomes, but the mechanism underlying the development of PE remains unclear. In this study, we performed a case-control study to compare the gut microbiota of PE (n = 26), abnormal placental growth (APG, n = 25) and healthy pregnant women (n = 28) and analyzed the potential pathogenic role of gut microbiota in PE progression. RESULTS: The clinical pathophysiological state did not affect the bacterial diversity, while the compositions of the gut microbiota were significantly altered in both the PE and APG groups compared with healthy pregnant women. At the phylum level, TM7 was significantly increased in women with APG. Heterogeneity was observed at the genus level, especially in genera with positive LDA scores, suggesting the stage-dependent effect of gut microbiota on the development of PE. The beneficial bacterium Lactobacillus was markedly depleted in the PE and APG groups but was only correlated with blood pressure (BP) and proteinuria levels in the PE group. Two different bacterial taxa belonged to Lactobacillus showed different correlations (OTU255 and OTU784 were significantly related to PE and APG, respectively). CONCLUSIONS: Our results indicated that shifts in the gut microbiota might occur from the early stages of the development of PE, which is of possible etiological and therapeutic importance.

Serum amyloid A, Serum Amyloid A1 and Haptoglobin in pregnant mares and their fetuses after experimental induction of placentitis.

Serum amyloid A (SAA) and Haptoglobin (Hp) are acute phase proteins, produced during inflammation, such as placentitis. In horses, SAA and SAA1 are protein coding genes. Objectives were to analyze SAA and Hp concentrations and relative abundance of SAA, SAA1 and Hp mRNA transcript in maternal and fetal tissues after experimental induction of placentitis or mares of a control group. Serum Amyloid A family proteins were in marked abundance in the stroma of the endometrium and chorioallantois associated with inflammatory cells. Maternal plasma SAA concentrations were greater (P = 0.01) in mares with experimentally induced placentitis compared to those of the control group. Maternal Hp from the groups were not different, but fetal Hp concentrations of mares with experimentally induced placentitis were greater (P = 0.02). Maternal plasma SAA and Hp concentrations were greater than fetal plasma concentrations in mares with experimentally induced placentitis (P < 0.05). Relative abundance of SAA mRNA transcript was greater in the maternal, fetal liver and chorioallantois of mares with experimentally induced placentitis (P < 0.05) compared to those in the control group. Interestingly, relative abundance of SAA1 mRNA transcript was greater in the chorioallantois of mares with experimentally induced placentitis (P < 0.05). The SAA and Hp concentrations, therefore, were greater in mares with induced placentitis. Furthermore, relative abundance of SAA1 mRNA transcript is specifically greater in the chorioallantois of mares with placentitis, which warrants further studies to elucidate the immunological response of SAA1 in the chorioallantois of mares with placentitis.

Salmonella Enteritidis foodborne infection induces altered placental morphometrics in the murine model.

INTRODUCTION: Salmonella foodborne disease during pregnancy causes a significant fetal loss in domestic livestock and preterm birth, chorioamnionitis and miscarriage in humans. These complications could be associated with alterations in placental structure. This study was aimed to determine how a low dose of Salmonella Enteritidis during late gestation affects placental histomorphometric in mice. METHODS: We used a self-limiting enterocolitis murine model. BALB/c pregnant animals received a low dose of Salmonella Enteritidis (3-4 x 102 CFU/mouse) on gestational day (GD) 15. At day 3 post infection bacterial loads, serum cytokines expression and placental histomorphometrics parameters were analyzed. RESULTS: We found that a sub-lethal infection with Salmonella induced a significant drop in fetal weight -to-placental weight-ratio and an increase in the placental coefficient. After bacterial inoculation maternal organs were colonized, inducing placental morphometric alterations, including increased placental thickness, reduced surface area, and diminished major and minor diameters. Also, foci of necrosis accompanied by acute leukocyte infiltration in decidual zone, reduction of vascular spaces and vascular congestion in labyrinth zone, were also evident in placentas from infected females on GD 18. Our data shows that placentas from infected mothers are phenotypically different from control ones. Furthermore, expression of IFN-gamma and IL-6 was up regulated in response to Salmonella in maternal serum. DISCUSSION: Our findings demonstrate that a low dose of Salmonella during late gestation alters the placental morphometry leading to negative consequences on pregnancy outcome such as significant reduction in fetal body weight.

Massive Perivillous Fibrin Deposition Associated With Placental Syphilis: A Case Report.

Massive perivillous fibrin deposition (MPFD) and the related entity of maternal floor infarction (MFI) are uncommon placental disorders of unknown etiology, associated with adverse obstetric outcome and a significant risk of recurrence. We describe a 19-year-old mother with untreated syphilis who delivered a male neonate with low birth weight, skin desquamation, and pneumonia. Placenta examination showed the expected changes for syphilis but unexpectedly, also showed MPFD. To our knowledge, this is the first report of MPFD associated with placental syphilis, thus expanding the list of etiologies that may be related to MPFD/MFI. It is postulated that the syphilis infection in our case led to a hypercoaguable state, eventually resulting in MPFD. In the right clinical setting, syphilis might be considered in the differential diagnosis when MPFD/MFI is observed on placental examination. The recurrence risk of MFPD/MFI associated with infections is believed to be lower than idiopathic cases and, by extrapolation, this lower risk should apply to syphilis as well.

Gardnerella vaginalis promotes group B Streptococcus vaginal colonization, enabling ascending uteroplacental infection in pregnant mice.

BACKGROUND: Group B Streptococcus is a common vaginal bacterium and the leading cause of invasive fetoplacental infections. Group B Streptococcus in the vagina can invade through the cervix to cause ascending uteroplacental infections or can be transmitted to the neonate during vaginal delivery. Some studies have found that women with a "dysbiotic" polymicrobial or Lactobacillus-depleted vaginal microbiota are more likely to harbor group B Streptococcus. Gardnerella vaginalis is often the most abundant bacteria in the vaginas of women with dysbiosis, while being detected at lower levels in most other women, and has been linked with several adverse pregnancy outcomes. Mouse models of group B Streptococcus and Gardnerella vaginalis colonization have been reported but, to the best of our knowledge, the two have not been studied together. The overarching idea driving this study is that certain members of the dysbiotic vaginal microbiota, such as Gardnerella vaginalis, may directly contribute to the increased rate of group B Streptococcus vaginal colonization observed in women with vaginal dysbiosis. OBJECTIVE: We used a mouse model to test the hypothesis that vaginal exposure to Gardnerella vaginalis may facilitate colonization and/or invasive infection of the upper reproductive tract by group B Streptococcus during pregnancy. STUDY DESIGN: Timed-pregnant mice were generated using an allogeneic mating strategy with BALB/c males and C57Bl/6 females. Dams were vaginally inoculated at gestational day 14 with group B Streptococcus alone (using a 10-fold lower dose than previously reported models) or coinoculated with group B Streptococcus and Gardnerella vaginalis. Bacterial titers were enumerated in vaginal, uterine horn, and placental tissues at gestational day 17. The presence (Fisher exact tests) and levels (Mann-Whitney U tests) of bacterial titers were compared between mono- and coinoculated dams in each compartment. Relative risks were calculated for outcomes that occurred in both groups. Tissue samples were also examined for evidence of pathophysiology. RESULTS: Inoculation of pregnant mice with 107 group B Streptococcus alone did not result in vaginal colonization or ascending infection. In contrast, coinoculation of group B Streptococcus with Gardnerella vaginalis in pregnant mice resulted in a 10-fold higher risk of group B Streptococcus vaginal colonization (relative risk, 10.31; 95% confidence interval, 2.710-59.04; P=.0006 [Fisher exact test]). Ascending group B Streptococcus infection of the uterus and placenta occurred in approximately 40% of coinoculated animals, whereas none of those receiving group B Streptococcus alone developed uterine or placental infections. Immunofluorescence microscopy revealed group B Streptococcus in both the maternal and fetal sides of the placenta. Histologic inflammation and increased proinflammatory cytokines were evident in the setting of group B Streptococcus placental infection. Interestingly, placentas from dams exposed to group B Streptococcus and Gardnerella vaginalis, but without recoverable vaginal or placental bacteria, displayed distinct histopathologic features and cytokine signatures. CONCLUSION: These data suggest that Gardnerella vaginalis vaginal exposure can promote group B Streptococcus vaginal colonization, resulting in a greater likelihood of invasive perinatal group B Streptococcus infections. These findings suggest that future clinical studies should examine whether the presence of Gardnerella vaginalis is a risk factor for group B Streptococcus vaginal colonization in women. Because Gardnerella vaginalis can also be present in women without bacterial vaginosis, these findings may be relevant both inside and outside of the context of vaginal dysbiosis.

Serum cortisol and thyroid hormone concentrations and survival in foals born from mares with experimentally induced ascending placentitis.

BACKGROUND: There are few publications on occurrence of nonthyroidal illness syndrome in foals and on the prognostic value of cortisol and thyroid hormone (TH) concentrations in newborn foals. OBJECTIVES: To determine serum cortisol and TH concentrations (total and free thyroxine: T4 and F T4 ; total and free triiodothyronine: T3 and F T3 ) in foals born from mares with placentitis, to determine their association with survival, and their use as prognostic markers. ANIMALS: A cohort of 29 newborn foals comprising 5 Control, 14 Low-risk, and 10 Sick foals were evaluated over the first week of life. METHODS: In this prospective study foals born to mares with experimentally-induced placentitis were assigned to Low-risk or Sick groups while foals born to control mares were classified as Control based on clinical findings. Foals were also classified as Term (n = 13), Dysmature (n = 7), or Premature (n = 9), and survival rate was recorded. Serum cortisol and TH hormone concentrations were measured at 0, 12, 24, 48, and 168 hours of life. RESULTS: Sick non-surviving foals had lower (P < .05) T3 : cortisol ratio at 12 (3.68 ± 1.06 versus 18.58 ± 2.78), 24 (5.47 ± 2.34 versus 23.40 ± 3.82), and 48 (10.47 ± 6.29 versus 26.6 ± 2.90) hours of life when compared to Sick surviving foals and lower (P < .05) T4 : cortisol ratio at 12 (75.12 ± 21.71 versus 414.47 ± 58.47) and 24 hours (127.83 ± 55.21 versus 430.87 ± 80.31) after birth than Sick surviving foals. CONCLUSION AND CLINICAL IMPORTANCE: Placental infections can impair fetal thyroid function. Low T3 : cortisol and T4 : cortisol ratios seem to be good prognostic markers in newborn foals.

Analysis of the capacity of Salmonella enterica Typhimurium to infect the human Placenta.

INTRODUCTION: Salmonella species are gram-negative facultative intracellular bacteria that are common causes of foodborne illness in North America. Infections by Salmonella during pregnancy are a significant cause of fetal loss in domestic livestock, and fetal and maternal mortality in mice. Furthermore, Salmonella infection is associated with miscarriage, stillbirth and preterm birth in pregnant women. Despite these collective associations, the extent to which Salmonella can infect the human placenta has not been investigated. METHODS: Human placental villous explants from several gestational ages were exposed to Salmonella enterica serovar Typhimurium (STm) ex vivo. Infection was assessed by colony forming unit assay and whole mount immunofluorescence (WMIF). RESULTS: Viable bacteria were recovered from placental villous explants of all gestational ages tested, but the bacterial burden was highest in 1st trimester explants. Bacterial numbers did not change appreciably with time post-infection in explants from any gestational age examined, suggesting that STm does not proliferate in placental villi. Exposure of villous explants to STm strains defective for the type III secretion systems revealed that Salmonella pathogenicity island 1 is essential for optimal invasion. In contrast to placental explants, STm infected and proliferated within villous cytotrophoblast cells isolated from term placentas. WMIF demonstrated that STm was restricted primarily to the syncytiotrophoblast layer in infected placentas. DISCUSSION: Our study demonstrates that STm can invade into the syncytiotrophoblast but does not subsequently proliferate. Thus, the syncytiotrophoblast may function as a barrier to STm infection of the fetus.

Placental and pulmonary cryptococcosis associated with fungemia in patient with acquired immunodeficiency syndrome.

Cryptococcosis is a systemic mycosis with a chronic or subacute progression caused by the inhalation of dehydrated yeasts or basidiospores. The causative agents are C. gattii and C. neoformans. The latter is more commonly associated with cellular immunodeficiency and is not rare in patients with Acquired Immunodeficiency Syndrome (AIDS). Cryptococcosis is common in pregnant women with AIDS; however, it is uncommon for the placenta to be affected, with few reported cases in the literature. We present the case of a pregnant woman with AIDS who had placental and pulmonary cryptococcosis associated with fungemia, with a satisfactory clinical outcome obtained after therapy.

Microorganisms in the Placenta: Links to Early-Life Inflammation and Neurodevelopment in Children.

Prenatal exposure to various stressors can influence both early and later life childhood health. Microbial infection of the intrauterine environment, specifically within the placenta, has been associated with deleterious birth outcomes, such as preterm birth, as well as adverse neurological outcomes later in life. The relationships among microorganisms in the placenta, placental function, and fetal development are not well understood. Microorganisms have been associated with perinatal inflammatory responses that have the potential for disrupting fetal brain development. Microbial presence has also been associated with epigenetic modifications in the placenta, as well other tissues. Here we review research detailing the presence of microorganisms in the placenta and associations among such microorganisms, placental DNA methylation, perinatal inflammation, and neurodevelopmental outcomes.

Pro- and anti-inflammatory effects of sulforaphane on placental cytokine production.

Placental inflammation increases the risk of adverse pregnancy outcomes and possibly neurodevelopmental disorders in the offspring. Previous research suggests it may be possible to modulate the placental immune response to bacteria to favor an anti-inflammatory phenotype with dietary factors. Sulforaphane (SFN) is a dietary supplement with known anti-inflammatory activities, however, its effects on placental cytokine production are unclear. Therefore, we evaluated the effects of SFN on biomarkers of inflammation and neurodevelopment under basal conditions and a setting of mild infection. Placental explant cultures were established and treated with up to 10 µM SFN in the presence and absence of 107 CFU/ml heat-killed E. coli. Concentrations of IL-1ß, TNF-α, IL-6, sgp130, HO-1 and BDNF in conditioned medium were quantified by immunoassay. SFN increased antioxidant HO-1 expression in the absence, but not the presence, of infection. SFN inhibited IL-1ß and IL-10, but tended to promote, TNF-α production by bacteria-stimulated cultures. IL-6 and BDNF were inhibited by SFN irrespective of co-treatment with E.coli. A negative regulator of IL-6 signaling, sgp130, was increased by SFN under basal conditions, but not in E. coli-stimulated cultures. These results suggest that SFN has mixed effects on the placenta inhibiting both pro-inflammatory (IL-1ß) and anti-inflammatory factors (IL-10) but promoting regulators of oxidative stress and inflammation (HO-1 and sgp130) in an infection-dependent manner.

Cortisol, progesterone, 17αOHprogesterone, and pregnenolone in foals born from mare's hormone-treated for experimentally induced ascending placentitis.

This study aimed to evaluate steroid hormones in foals born from mares treated for ascending placentitis with different combinations of trimethoprim-sulfamethoxazole (TMS), flunixin meglumine (FM), long-acting altrenogest (ALT) and estradiol cypionate (ECP) for ten consecutive days, starting two days after experimental induction of placentitis with Streptococcus zooepidemicus. Fourty-six pregnant mares and respective foals were assigned as healthy group (Control, n = 8) or treated groups as follows: TMS+FM (n = 8), TMS+FM+ALT (n = 8), TMS+FM+ALT+ECP (n = 6), TMS+FM+ECP (n = 6) and no treatment (NO TREAT n = 10). At delivery, foals were classified as high-risk or low-risk based on clinical and hematologic findings, and survival rates were recorded during the first week of life for comparisons across groups. Cortisol, progesterone, 17αOHprogesterone, and pregnenolone concentrations were determined via immunoassays in 31 of the 46 foals immediately after foaling (0 h), at 12, 24, 48 h, and seven days post-partum (168h). At birth, serum cortisol concentrations were higher in Control and TMS+FM+ECP foals than in remaining groups (p < 0.05). Foals in TMS+FM+ALT and TMS+FM groups had higher 17αOHprogesterone concentrations at 24 h and 48 h, respectively (p < 0.05). Pregnenolone concentrations were higher in TMS+FM than TMS+FM+ALT+ECP foals at 7 days (p < 0.05). High-risk and non-surviving foals had decreased concentrations of cortisol at parturition, but increased concentrations of progesterone from 0 h to 48 h. Pregnenolone and 17αOHprogesterone concentrations were increased and pregnenolone after 12 h in high-risk and non-surviving foals (p < 0.05). In conclusion, adding ECP to the treatment of experimentally-induced placentitis appears to improve foal viability and endocrine response. Cortisol and progestogen profiles were abnormal in high-risk and non-surviving foals, and those treated with ALT or TMS+FM only.

Spectrum of Changes Seen With Placental Intravascular Organisms.

Fetal bacterial infections are a common cause of fetal/neonatal morbidity and mortality. The pathologic correlates of congenital bacterial infection include acute chorioamnionitis, acute villitis, and acute intervillositis. The strength of the association of congenital bacterial infection differs among these pathologies. Acute chorioamnionitis results usually from an ascending infection, and damage to the fetus is thought to be cytokine driven rather than damage secondary to bacteremia. Acute villitis is strongly associated with fetal sepsis due to congenital infections. A much less common variant on acute villitis pattern has been described with additional presence of bacteria in the fetal capillaries of the chorionic villi. We describe the spectrum of bacteria that would induce this unique pattern. The histological archives were searched from 2 institutions for cases with intravascular bacteria present in the villous capillaries of the placenta. Thirteen cases were identified, of which 11 cases had acute chorioamnionitis and all cases showed an acute villitis. Eight cases had Escherichia coli identified and 3 cases had Group B Streptococcus. All cases were associated with fetal death. In 9 cases, the mother showed signs of a significant infection including 1 maternal death. We conclude that finding intravascular bacteria is a serious complication of congenital infection with serious fetal and maternal sequela.

Changes in maternal pregnane concentrations in mares with experimentally-induced, ascending placentitis.

The objectives of this study were to compare via liquid chromatography-tandem mass spectrometry (LC-MS/MS) progesterone (P4), 5α-dihydroprogesterone (DHP), allopregnanolone, 3ß-hydroxy-5α-pregnan-20-one (3ß5P), 20α-hydroxy-5α-pregnan-3-one (20α5P), 5α-pregnan-3ß,20α-diol (ßα-diol), and 5α-pregnan-3ß,20ß-diol (ßß-diol) concentrations in plasma of mares with experimentally-induced, ascending placentitis compared to gestationally age-matched control mares. Placentitis was induced via intracervical inoculation of Streptococcus equi spp. zooepidemicus between 260 and 280 days of gestation. Placentitis mares were subdivided into those which aborted in less than eight days (n = 6; acute) and those that aborted at ≥ 8 days after inoculation (n = 9; chronic). Ten pregnant mares at similar gestational ages served as healthy controls. Pregnanes were measured for days (-8), -6, -4, -3, -2, -1, and 0 days preceding abortion in the treated mares, and for the matched days of gestation in the control mares by LC-MS/MS and by immunoassay for immunoreactive (ir) P4. In mares with chronic placentitis, concentrations of DHP and its downstream metabolites (allopregnanolone, 3ß5P, 20α5P, ßα-diol) increased at 2-8 days prior to abortion compared to control mares. Of these pregnanes, 20α5P and ßα-diol increased at eight days prior to abortion and demonstrated the largest increase (approximately 3 to 4×) in mares with chronic placentitis compared to control mares. Concentrations of P4 determined by LC-MS/MS were at or below the limit of detection (0.5 ng/mL) for control mares and did not increase significantly in mares with chronic placentitis. Immunoreactive-P4 was increased at two days prior to abortion in mares with chronic placentitis but was not different from controls in mares with acute placentitis. In mares with acute placentitis, concentrations of DHP, allopregnanolone, 3ß5P, 20α5P, and ßα-diol decreased within 0-3 days prior to abortion. In mares with chronic placentitis, the patterns of increased pregnanes metabolized by the placenta was similar to changes in maternal pregnanes noted in normal mares beyond Day 300 of gestation and likely represent the effects of fetal stress and adrenal activation on pregnane metabolism by the fetus and placenta. Decreases in these same pregnanes in mares with acute cases likely reflect extreme fetal or placental compromise.

Survey for Placental Disease and Reproductive Pathogens in the Endangered Hawaiian Monk Seal ( Neomonachus schauinslandi).

There is considerable temporal and spatial variability in the reproductive rates of Hawaiian monk seals (HMS; Neomonachus schauinslandi). Poor reproductive performance limits the recovery of this endangered species; however, causal factors are not fully understood. There is serologic evidence that HMS are exposed to pathogens that can impact reproductive success, but the prevalence of placental infections in HMS has not been evaluated. Placental tissues ( n=50), including tissues from 25% of known HMS births, were opportunistically collected in 2011 from six Northwestern Hawaiian Islands and three main Hawaiian Islands. Reproductive histories of the sampled females were representative of the breeding population, as determined through comparisons in age of primiparity and mature reproductive rate. Placental tissues were examined histologically and screened by PCR for Coxiella burnetii, Brucella spp., Chlamydia spp., Leptospira spp., herpesviruses, and Toxoplasma gondii. There was no histologic evidence of placental pathology, and molecular analyses were negative. These negative results can be used to estimate pathogen prevalence in the nonsampled population. For an approximate population size of 1,300 HMS, we can estimate with 99% confidence that the prevalence of each pathogen tested is 9% or less. This is low relative to other pinnipeds and indicates that factors other than reproductive pathology, such as resource limitation, may drive variability in HMS reproductive rates. Further investigation into the cumulative impacts of resource limitation and other stressors on HMS reproduction is warranted.

Estradiol cypionate aided treatment for experimentally induced ascending placentitis in mares.

The overall goal of this study was to assess the efficacy of various therapeutic combinations of estradiol cypionate (ECP, a long-acting estrogen) and altrenogest (ALT, a long-acting progestin) in addition to basic treatment for placentitis with trimethoprim-sulfamethoxazole (TMS) and flunixin meglumine (FM). Specific outcomes measured in this experiment were (i) time from induction of bacterial placentitis to delivery, and foal parameters (high-risk, survival, and birth weight); and (ii) serum steroid concentrations (progesterone, 17α-hydroxyprogesterone, 17ß-estradiol, and cortisol) in response to treatment. Pregnant mares (∼300 days gestation, n = 46) were randomly assigned into healthy mares (control group, CONT, n = 8) and mares with experimentally induced ascending placentitis (n = 38). Placentitis was induced via intracervical inoculation of Streptococcus equi subspecies zooepidemicus. Thereafter, placentitis induced mares were randomly assigned into: (1) basic treatment, TMS+FM (n = 8); (2) basic treatment with ALT supplementation, TMS+FM+ALT (n = 8); (3) basic treatment with ECP supplementation, TMS+FM+ECP (n = 6); (4) basic treatment with ALT and ECP supplementation TMS+FM+ALT+ECP (n = 6); and (5) no treatment (INOC, n = 10). Treatments were started 48 h after bacterial inoculation and carried out for ten consecutive days. Blood samples were collected daily, and mares were assessed for signs of placentitis until the mare delivered, or for ten consecutive days after onset of treatment. Steroids were analyzed via RIA. Continuous data were analyzed by ANOVA, and categorical data analyzed by Fisher's exact test. Significance was set at p < 0.05. Foal survival at parturition and seven days post-delivery were similar across treated groups (66.7-100%), and to the CONT group. Similar to CONT group, mares in the TMS+FM+ECP group had no high-risk foals while mares in the other groups had higher incidences (50-75%) (p < 0.05). The inclusion of ECP in the treatments resulted in foals with body weight similar to CONT group (p > 0.05). There were no group effects or time by group interactions on concentrations of steroids assessed herein (p > 0.05). In conclusion, in addition to basic treatment TMS+FM, mares with experimentally induced ascending placentitis benefited from ECP supplementation. Conversely, ALT did not appear to make a difference in outcomes. The immunoassays used for measurements of steroid concentrations did not appear useful to assess treatment response.