Publications by authors named "Yasuo Nambo"

Article Synopsis
  • Equine testicular arteritis can result from nematode larvae migration or equine arteritis virus (EAV) infection, but cases without these infections exist, and their causes are not fully understood.
  • A 3-year-old male heavy draft horse exhibited scrotal enlargement due to testicular arteritis that was not linked to known infections, showing significant edema in the pampiniform plexus.
  • Histological examination revealed non-suppurative and necrotizing arteritis, with lymphocyte infiltration and arterial wall damage, yet the underlying reason for the condition remained undetermined.
View Article and Find Full Text PDF
Article Synopsis
  • - Ultrasound is a key tool for tracking potential pregnancy risks in horses, and this case report illustrates the rare occurrence of an enlarged bladder in an equine fetus.
  • - An 8-year-old Hokkaido pony, pregnant via embryo transfer, showed bladder abnormalities at 215 days, with a second bladder detected by 257 days, while kidney function remained normal.
  • - Throughout gestation, maternal progesterone levels were monitored, showing elevated levels leading up to successful foaling at 363 days, marking the first documentation of equine fetal enlarged bladder development alongside ultrasound findings.
View Article and Find Full Text PDF
Article Synopsis
  • Japanese native horses, comprising 8 breeds, are at risk of extinction, prompting the use of embryo transfer (ET) to aid in their reproduction.
  • The study involved transporting non-cryopreserved embryos from Kiso ponies in Nagano to Hokkaido, covering a distance of 1500 km over 9 hours in controlled conditions.
  • Successful transfer resulted in one mare giving birth to a healthy foal, indicating that this method could help increase the population of Japanese native horses.
View Article and Find Full Text 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.

View Article and Find Full Text PDF

We performed a standing hand-assisted laparoscopic ovariectomy in a draft mare that presented with high serum anti-Müllerian hormone (AMH) level and had an enlarged single cystic ovary. Histopathological examination revealed no tumor cell proliferation in the ovary, but the presence of a large ovarian cyst was confirmed. In the diagnosis of abnormal ovaries in mares, a comprehensive assessment should be performed, including the monitoring of ovarian morphology and biomarkers over time, to determine the disease prognosis and treatment plan.

View Article and Find Full Text PDF

The objective of this study was to examine the effect of prostaglandin F2 (dinoprost) and oxytocin administration on uterine polymorphonuclear neutrophil counts in the Japanese heavy draft mare. To compare polymorphonuclear neutrophil (PMN) counts in the endometrium, a total of 162 samples were collected from 54 estruses of 47 mares (before ovulation, day 0, and day 2) using a double-guarded cytology brush. Dinoprost (PG; 5 mg) was administered intramuscularly (i.

View Article and Find Full Text PDF
Article Synopsis
  • A proper vascular network is critical for the placenta's function, and abnormalities in this network can lead to pregnancy issues.
  • Researchers hypothesized that estrogens play a key role in the growth of placental blood vessels during equine pregnancy, and used letrozole to inhibit estrogen production in mares during early gestation.
  • Results showed that decreased estrogen levels led to reduced fetal weight, fewer blood vessels in the placenta, and changes in gene expression related to blood vessel formation, highlighting the importance of estrogen for placental vascular development in horses.
View Article and Find Full Text PDF

Equine-Assisted Therapy (EAT) is gaining popularity. Ultrasound examination is used to decrease the abortion rate in horses. In this study, to monitor fetal well-being throughout the gestation for EAT, we measured fetal heart rate (FHR), fetal eye orbit (FEO), fetal gonad length (FGL), fetal kidney length (FKL), and the combined thickness of the uterus and placenta (CTUP) by ultrasonography in pony mares.

View Article and Find Full Text PDF

The main difficulty of large equine embryo cryopreservation is the replacement of blastocoel fluid with cryoprotectant solution. The objective of this study was to improve the cryopreservation of large equine embryos with PMAP and/or LAP. Embryos were collected via the non-surgical transcervical procedure and divided into three groups based on their size (A ≤ 300 µm, 300 µm View Article and Find Full Text PDF

Granulosa cell tumor (GCT) is a benign tumor which affects the mare's ovaries. In this report, a case of unilateral GCT in an ovary, which weighed 17.04 kg, of a 9-year-old Breton draft mare is described.

View Article and Find Full Text PDF
Article Synopsis
  • Researchers studied how exercise and emotional stress impact hormone levels in Thoroughbred horses.
  • They conducted two experiments: one focusing solely on exercise stress and the other combining exercise with emotional stress from a loud racetrack video.
  • Results showed that both types of stress increased the secretion of prolactin and growth hormone, with exercise causing a quick rise that lasted after the workout, while emotional stress also boosted prolactin levels.
View Article and Find Full Text PDF

Although equine gestation is unique from the standpoint of fetal gonadal enlargement and regression, the activator of this process is still unknown. The present study aimed to show a possible role of activin during equine gestation. In the first experiment, weekly plasma samples from six pregnant mares were used to measure activin A.

View Article and Find Full Text PDF
Article Synopsis
  • The study investigated the expression of surfactant proteins A and D (SP-A and SP-D) in the uterine and placental tissues of 13 pregnant mares using specific antibodies.
  • Strong positive reactions for both proteins were found in the placenta's trophoblasts during the later stages of gestation, while weaker reactions were noted in the uterine epithelial cells.
  • This research is the first to document changes in SP-A and SP-D expression levels in mare endometrium throughout pregnancy, with increased levels observed after the second trimester.
View Article and Find Full Text PDF

Insulin-like peptide 3 (INSL3) is an important hormone for testicular descent during embryonic development and a factor for assessing functional status of Leydig cells of testes, but there is limited number of equine studies. Anti-Müllerian hormone (AMH) is a useful diagnostic marker for cryptorchidism in horses. This study aimed to compare serum concentrations and testicular expression intensity of INSL3 and AMH in intact and cryptorchid male horses.

View Article and Find Full Text PDF

The purpose of this study was to elucidate the colostral and foal serum immunoglobulin G (IgG) concentration values in heavy draft horses in Japan and to examine the effects of peripartum mare condition on colostral immunity. Colostrum was obtained 1 hr after foaling (pre-suckling; n=178). Blood was collected from the jugular vein of the foals (n=147) at 24 to 48 hr after birth.

View Article and Find Full Text PDF

Until now, there have been no reports of foals born through embryo transfer after artificial insemination using frozen semen in Japan. The aims of this study were to develop a riding crossbred horse and evaluate the prospects of embryo transfer technology in multiplying horse population. In both donor and recipient mares, luteolysis was induced by the administration of 0.

View Article and Find Full Text PDF

The peripheral blood concentrations of insulin-like peptide 3 (INSL3) have been detected in many mammalian species, but the level of INSL3 in horse remains unknown. The objectives were to develop a time-resolved fluorescence immunoassay (TRFIA) to detect INSL3 concentrations from horse blood as well as to determine the age-related and seasonal changes of plasma concentrations of INSL3 and testosterone from birth to early-puberty in Thoroughbred male horse (n = 11). Monthly blood sample and measurement of body weight, height, chest and cannon bone size were done from birth until 16 mo.

View Article and Find Full Text PDF

There has been no report of equine embryo transfer in Japan for the last 24 years. Our objective was to establish an effective protocol for embryo transfer in domestic horse. A Hokkaido native pony was bred by deep-horn artificial insemination with frozen semen from a Connemara pony.

View Article and Find Full Text PDF
Article Synopsis
  • Activin is a crucial hormone secreted by equine uterine glands, essential for pregnancy establishment and maintenance in mares.
  • The study focused on identifying activin receptors (ActRs) in uteroplacental tissues from seven pregnant Thoroughbred mares at various stages of pregnancy.
  • All four isoforms of ActR were found expressed in key uteroplacental tissues, indicating activin's likely important role throughout the entire pregnancy process.
View Article and Find Full Text PDF
Article Synopsis
  • The study examined the combined thickness of the uterus and placenta (CTUP) in 35 pregnant heavy draft horses during the last months of pregnancy, categorizing them into three groups based on health conditions of the placenta and fetus.
  • CTUP measurements significantly increased as pregnancy progressed, with the normal group showing higher values than other horse breeds, while both the placentitis and abnormal groups displayed CTUP values above the normal range.
  • Ultrasonographic findings indicated signs of placental separation and abnormalities in all groups, highlighting that increased CTUP can be a marker for detecting placentitis and complications in pregnancies of heavy draft horses.
View Article and Find Full Text PDF
Article Synopsis
  • * The torsion cases included varied directions: four clockwise, two counterclockwise, and one undetermined, with all torsions corrected via surgery.
  • * Hormone levels were monitored in two mares, showing elevated progesterone that was treated, and all mares that left the hospital with live fetuses could continue to carry them successfully.
View Article and Find Full Text PDF

The purpose of this study was to evaluate foaling rates of mares that were rebred after the pregnancy loss in same reproductive season and to examine factors influencing them in Hidaka, Japan. The study included 82 Thoroughbred mares that had experienced pregnancy loss. The foaling rate of the mares that were rebred after pregnancy loss was 57.

View Article and Find Full Text PDF
Article Synopsis
  • The study focused on insulin-like growth factor 2 (IGF2) and its role in fetal development and adult physiology, specifically in horses.
  • Researchers identified a new variant of equine IGF2 mRNA that includes untranslated regions but shares the same amino acid sequence as the canonical form.
  • The findings revealed a specific genetic variation in Thoroughbred horses and established a baseline for IGF2 expression patterns in equine fetal tissues, indicating conserved functions across species.
View Article and Find Full Text PDF

Problems associated with the proximal metacarpal region, such as an osseous injury associated with tearing of Sharpey's fibers or an avulsion fracture of the origin of the suspensory ligament (OISL), are important causes of lameness in racehorses. In the present study, four Thoroughbred racehorses (age range, 2-4 years) were diagnosed as having forelimb OISL and assessed over time by using standing magnetic resonance imaging (sMRI). At the first sMRI examination, all horses had 3 characteristic findings, including low signal intensity within the trabecular bone of the third metacarpus on T1-weighted images, intermediate-to-high signal intensity surrounded by a hypointense rim on T2*-weighted images, and high signal intensity on fat-suppressed images.

View Article and Find Full Text PDF
Article Synopsis
  • The study compared the effects of different climate conditions and light supplementation (LS) on the growth and hormonal changes in trained Thoroughbred yearling horses in Japan, focusing on those from Hokkaido (north) and Miyazaki (south).
  • Yearlings were divided into two groups (control and LS) with LS groups receiving extended daylight.
  • Findings indicated that Hokkaido yearlings had higher basal metabolism and lower initial growth parameters, but with LS, their hormone levels and growth metrics improved, aligning more closely with those from warmer Miyazaki.
View Article and Find Full Text PDF