Journal of Equine Science
Online ISSN : 1347-7501
Print ISSN : 1340-3516
ISSN-L : 1340-3516
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  • Naoki SASAKI, Yasunobu NISHI, Yumi FUJIWARA, Tetsuya TAKEYAMA, Hayata ...
    Type: —Full Paper—
    2021 Volume 32 Issue 2 Pages 27-30
    Published: 2021
    Released: June 18, 2021
    JOURNALS OPEN ACCESS

    Gastric ulcers cause appetite loss, poor body condition, and colic in horses. This study investigated the protective effect of a rice fermented extract on the gastric mucosa in 17 healthy Thoroughbreds. For one month, horses in the rice fermented extract (nine horses) and control (eight horses) groups were orally administered a rice fermented extract (100%; 0.2 ml/kg, SID) and tap water (0.2 ml/kg), respectively. Gastric endoscopic images were obtained before and one month after rice fermented extract administration. The gastric ulcer score was lower after administration (median, 1; maximum, 2; minimum, 1) than before administration (median, 4; maximum, 4; minimum, 3) in the rice fermented extract group (P<0.05). In conclusion, the administration of a rice fermented extract for one month improves gastric mucosal lesions in Thoroughbreds with gastric ulcers.

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  • Jeffrey A. FAWCETT, Hideki INNAN, Takeru TSUCHIYA, Fumio SATO
    Type: —Full Paper—
    2021 Volume 32 Issue 2 Pages 31-37
    Published: 2021
    Released: June 18, 2021
    JOURNALS OPEN ACCESS

    Many studies have reported that advancing age in broodmares has a negative impact on the reproductive performance of horses. However, although the ages at first and last mating vary among broodmares, it is unknown how this variation affects the correlation between age and reproductive performance in mares. Here, in order to examine the effects of the ages at first and last mating, we analyzed all recorded mating events for Thoroughbreds in Japan from 1997 to 2017. We found that the live foal birth rate of mares with a younger age at first mating indeed declined at an earlier age than those with an older age at first mating and that the number of years since the first mating also contributes to the decline in the birth rate. We also found that the live foal birth rate and mean earnings of the produced foals are much higher for mares with an older age at last mating compared with mares with a younger age at last mating. Our results should aid breeders in assessing the value of broodmares and designing breeding strategies.

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  • Pramod DHAKAL, Nobuo TSUNODA, Yasuo NAMBO, Hiroyuki TANIYAMA, Kentaro ...
    Type: —Full Paper—
    2021 Volume 32 Issue 2 Pages 39-48
    Published: 2021
    Released: June 18, 2021
    JOURNALS OPEN ACCESS

    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. In the second experiment, eight pregnant mares carrying female (gestational days 110, 140, 180, and 270) and male fetuses (gestational days 120, 180, 225, and 314) were used for immunohistochemistry of activin receptors (IA, IB, IIA, IIB), and their intracellular mediators (Smad2, Smad3, Smad4). Activin A levels in maternal circulation remained low until fourth weeks of gestation, thereafter, started to increase, and peaked first at 11 weeks of gestation. The second significant peak was observed on the day of parturition. Activin receptors type IA, IB, IIA, and IIB were immunostained in interstitial and germ cells of fetal ovaries and testes along with utero-placental tissues. Smad2, Smad3, and Smad4 were also immunolocalized in all these organs. These results demonstrated the activin-producing capacity of utero-placental tissues, and also evidenced the existence of activin receptors and functional signaling molecules in these organs. The first increment in circulating activin A in maternal circulation coinciding with the timing of initiation of fetal gonadal enlargement suggests that activin from the utero-placental tissues may have a stimulatory role in fetal gonad enlargement and utero-placental development in mares, whereas the second peak could be important to follicular development in the maternal ovary for foal heat.

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Note
  • Tomoki KITAURA, Fumio SATO, Testuro HADA, Mutsuki ISHIMARU, Rumi KODAM ...
    Type: —Note—
    2021 Volume 32 Issue 2 Pages 49-53
    Published: 2021
    Released: June 18, 2021
    JOURNALS OPEN ACCESS

    The secretion of prolactin and growth hormone in response to exercise and emotional stresses was investigated in Thoroughbreds. Two experiments were performed: one with loading of only exercise stress and one with simultaneous loading of exercise and emotional stresses. Exercise stress was loaded in 4 steps using a treadmill for horses: pre-exercise period (5 min), walking period (6.5 min), galloping period (3 min), and cooling down period (10 min). Emotional stress was loaded by showing a loud video of an audience at a racetrack during the walking period. The results clearly demonstrated that exercise stress rapidly increased the secretion of prolactin and growth hormone and that secretion of them persisted for a specific period after the exercise. In addition, emotional stress promoted prolactin secretion.

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  • Metha CHANDA, Chanikarn PUANGTHONG, Watcharapol PATHOMSAKULWONG, Tawan ...
    Type: —Note—
    2021 Volume 32 Issue 2 Pages 55-60
    Published: 2021
    Released: June 18, 2021
    JOURNALS OPEN ACCESS

    Two horses diagnosed with underrun heels leading to navicular syndrome were fitted with Z-bar shoes. They occasionally showed moderate lameness on the affected legs after the sixth and tenth consecutive farrier adjustments. The affected hooves were sensitive to compression of the frog and sole in their palmar regions. Modified Z-bar shoes were created and shod on the lame legs based on previous with regional anaesthesia and recent clinical examination. The lameness scores were slightly improved at the first shoeing with the modified Z-bar shoes but were markedly improved at four and eight weeks aftershoeing, without medication. The modified Z-bar shoes in this report could potentially protect the palmar structure damaged by usual Z-bar shoes and contribute to reducing pathogenic impacts deriving from underrun heels and navicular syndrome.

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  • Aesha A. OTHMAN, Murad A. HIBLU, Mohamed Salah ABBASSI, Yousef M. ABOU ...
    Type: —Note—
    2021 Volume 32 Issue 2 Pages 61-65
    Published: 2021
    Released: June 18, 2021
    JOURNALS OPEN ACCESS

    The present study investigated the colonization rates and antimicrobial susceptibility of Staphylococcus species isolated from the nostrils of healthy horses. A nonselective laboratory approach was applied, followed by confirmation using a Phoenix automated microbiological system. Among the 92 horses included in the study, 48.9% (45/92) carried Staphylococcus species of mostly the coagulase-negative staphylococci (CoNS) type yielding 70 Staphylococcus strains. Of these strains, 37.1% (26/70; 24 CoNS and 2 coagulase-positive staphylococci; CoPS) were identified as methicillin-resistant staphylococci (MRS) expressing significant resistance to important antimicrobial classes represented mainly by subspecies of CoNS. This is the first study reporting a high prevalence of various Staphylococcus species, particularly strains of CoNS expressing multidrug resistance patterns of public health concern, colonizing healthy horses in Libya.

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  • Munkhtuul TSOGTGEREL, Masaaki TAGAMI, Kenichi WATANABE, Harutaka MURAS ...
    Type: —Note—
    2021 Volume 32 Issue 2 Pages 67-72
    Published: 2021
    Released: June 18, 2021
    JOURNALS OPEN ACCESS

    Granulosa cell tumor (GCT) is a benign tumor which affects the mareʼs 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. A transrectal ultrasonography exam revealed a unilateral multi-cystic enlarged ovary. Laparoscopic ovariectomy was difficult due to enlargement of blood vessels in the ovarian broad ligament. The mare was necropsied, and the pathological changes in the GCT-affected ovary and unaffected ovary were evaluated. The ovarian mass in the GCT-affected ovary had a cribriform pattern and was positive for anti-Müllerian hormone (AMH) and its receptor (AMHR2). The contralateral ovary showed no follicular development and was negative for AMH. AMHR2 was positively expressed in stromal cells. The AMH concentration in plasma was 4,210 ng/ml. This is the first report showing the presence of AMH (2,210 ng/ml) in ascites fluid, and it also shows that laparoscopic ovariectomy might not be suitable for larger ovaries affected by a GCT. Ultrasonographic, endocrine, and histopathological analyses were helpful for making a definitive diagnosis of GCT in this mare.

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