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application/pdf, Late-term fetal loss in horses is a major problem in the horse-breeding industry globally. Abnormal pregnancies should be diagnosed as early as possible to prevent abortions and other gestational problems. According to our previous longitudinal study in healthy pregnant mares, the plasma activin A concentration increases as pregnancy progresses. The aim of the present study was to compare plasma activin A concentrations in healthy pregnant Thoroughbred mares (n=40) with those in pregnant mares that suffered fetal loss or showed abnormal symptoms (n=30) during late gestation. This field study found that plasma activin A concentrations were higher in the abnormal group (pregnancy loss, red bag delivery, premature udder development, and vaginal discharge) than the normal group (P < 0.001; cutoff value: ≥ 138.2 pg/mL; sensitivity, 74.4%; specificity, 77.5%). More specifically, plasma activin A concentrations in the “symptom” and “abnormal delivery” subgroups were higher than those in gestational-age-matched normal groups (P < 0.001). Nevertheless, the plasma activin A concentration in the “normal delivery” subgroup was not different from that in the “abnormal delivery” subgroup in samples collected within 10 days before delivery. In conclusion, this study is the first to demonstrate a significantly earlier increase in plasma activin A concentration in abnormal pregnancies of Thoroughbred mares during late gestation. © 2022 Elsevier Inc.

Granulosa cell tumor (GCT) is a sex-cord stromal tumor in mares and causes infertility. The objective of this study was to localize anti-Mullerian hormone (AMH) and its receptor, anti-Mullerian hormone receptor type 2 (AMHR2), in ovarian tissue samples obtained from 11 Thoroughbred mares diagnosed with GCT. Immunohistochemistry revealed positive immunostaining for both AMH and AMHR2 in the granulosa-like cells of GCT. Furthermore, double immunofluorescence staining revealed the presence of colocalization of AMH and AMHR2 in granulosa-like cells of GCT in mares. These findings suggest that granulosa-like cells of GCT are a target of AMH, suggesting that AMH may have paracrine and autocrine function on granulosa-like cells of GCT in mares. Moreover, this is the first report to demonstrate the colocalization of AMH and its receptor, AMHR2, in GCT-affected ovaries of mares by using double immunofluorescence staining.

Recently, anti-Mullerian hormone (AMH) has been reported as a useful diagnostic marker for equine granulosa cell tumors (GCTs). The aim of this study was to examine and compare serum AMH and immunoreactive (ir)-inhibin concentrations in mares with ovarian abnormalities other than GCT compared to mares with known GCT in order to determine more useful diagnostic criteria. Mares with a possible GCT based upon history were subsequently classified into those with GCT confirmed by histopathology and mares with other abnormal ovaries (AO) without a GCT based on follow-up fertility information. Median concentrations of AMH were 72.6 ng/mL (quartiles: 20.6–458.5 ng/mL) in GCT and 0.70 ng/mL (0.26–1.44 ng/mL) in AO mares, and median concentrations of ir-inhibin were 2.36 ng/mL (1.65–3.79 ng/mL) in GCT versus 0.93 ng/mL (0.69–1.46 ng/mL) in AO mares. The cutoff values based on receiver operating characteristic (ROC) analysis were 4.70 ng/mL for AMH and 1.65 ng/mL for ir-inhibin. These cutoff values were slightly higher than the traditional value based on the normal reference range. The sensitivity, specificity, accuracy, and area under the ROC curve of AMH were higher than those of ir-inhibin. In conclusion, we demonstrated the diagnostic criterion of serum AMH concentration for equine GCT. Anti-Mullerian hormone is a more useful marker for diagnosis of equine GCT than ir-inhibin.

DNA parentage testing using microsatellite markers confirmed that a Thoroughbred foal conceived from a mare that was bred with two different stallions at an interval of 22 days in successive normal estrus cycles was not sired by the last mated stallion. The results of the stallions were confirmed by retesting DNA parentage test and video recording during the mating sessions. Clinical examinations excluded the absence of an embryo in the uterus after the first mating but confirmed the presence of twin embryos after the last mating, despite confirmation of only one ovulation. One of the twin embryos was crushed by hand, and the other embryo was normally delivered at 332 days after the last mating (354 days after the first mating). Furthermore, to identify similar cases in Thoroughbred mares, we retrospectively reviewed all breeding records over the previous 16 years in Japan and identified three similar cases among 7,787 foaled mares by stallion change. Because the mating interval was approximately one estrus cycle in these cases, pregnancy seemed unlikely to have resulted from prolonged survival of the sperm. Embryonic diapause characterized by delayed implantation of an embryo after the first mating should be strongly considered for proper identification in Thoroughbred lines.

The effects of dietary supplementation with astaxanthin and L-carnitine on serum markers and clinical incidence rate of exercise-induced muscle damage were studied in training horses. Sixty-three healthy Thoroughbred horses were randomly assigned to two groups and received the same base diet and exercise training throughout this study. The supplement (supp.) group (n = 31) received daily supplementation with astaxanthin (75 mg) and L-carnitine (3,000 mg) for 8 weeks, and the control (cont.) group (n = 32) received no supplementation. Blood samples were collected after high-intensity exercise training at 5 weeks before supplementation, 3 days (3d), and 8 weeks (8w) after the start of the supplementation. The blood samples were analyzed for creatine kinase (CK) activity and lactate dehydrogenase isoenzyme-5 (LDH-5), and a retrospective study was carried out by analyzing medical records for symptoms of exercise-induced muscle damage in both groups. Five horses (two of supp. group and three of cont. group) were excluded from this study for other disease. In the cont. group, CK activity at 8w was significantly increased compared with 3d, whereas the supp. group showed no significant change. After 8w, the CK activity of the supp. group was significantly lower than that of the cont. group. Additionally, the LDH-5 concentration of the supp. group also tended to be lower as compared with that of the cont. group. The incidence rate of exercise-induced muscle damage was significantly lower in the supp. group compared with the cont. group. These results suggest that continuous dietary administration of astaxanthin and L-carnitine attenuates exercise-induced muscle damage in horses.

This study aimed to examine fertility at foal heat and its relevance to body condition score (BCS) and blood nutritional metabolites in Thoroughbred mares. Thoroughbred mares foaled from 2006 to 2009 were included and classified into two groups: group C (conception; n = 34), which included mares that conceived during foal heat (within 3 weeks after foaling), and group NC (nonconception; n = 39), which included mares that did not conceive despite mating during their foal heat. BCS and blood samples were obtained 1 month before the expected foaling date and 1, 2, 3, and 4 weeks after foaling. Total protein (TP), albumin (Alb), blood urea nitrogen (BUN), aspartate aminotransferase (AST), gamma-glutamyltransferase (GGT), total cholesterol (T-Cho), triglyceride (TG), nonesterified fatty acid (NEFA), calcium (Ca), inorganic phosphate (iP), and magnesium (Mg) levels were measured using an automatic clinical chemistry analyzer. Repeated measures analysis of variance (ANOVA) and Student t-test were used to examine the differences between the two groups. No significant differences were observed between the two groups in any of the above-mentioned parameters at 1 month before the expected foaling date (Student t-test). Furthermore, no significant differences were observed between the two groups in serum levels of TP, Alb, AST, GGT, T-Cho, NEFA, Ca, and Mg and BCS at postpartum periods (repeated measures ANOVA). Serum TG, BUN, and iP levels remained lower in group NC than in group C after foaling (P

The purpose of this study was to investigate the changes in serum concentrations of prolactin (PRL), progestagens, and estradiol-17β and biochemical parameters during peripartum in an agalactic mare, as well as to study the periparturient indices of the foal. A 4-year-old Thoroughbred, primiparous, pregnant mare was diagnosed as agalactic from clinical conditions such as absence of observable udder development and weight loss of her foal after parturition. Serum PRL concentrations of the agalactic mare during prepartum tended to be lower than those of the control mares (19.5 ng/mL and 67.0 ± 15.0 ng/mL on the day of parturition, respectively). The progestagens and estradiol-17β concentrations were not markedly different between the agalactic mare and the control mares. Concentrations of γ-glutamyl transferase of the agalactic mare were higher than those of the control mares (P

s / Journal of Equine Veterinary Science 34 (2014) 232 232 Fig. 1. Progestin (ng/mL) and estrogen (pg/mL) levels in mares with surviving (n1⁄4408) and dead (n1⁄451) foals at 20-day intervals of gestation. Significant differences *P