Journal of Equine Science
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Volume 27 , Issue 2
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Review Article
  • Atsushi HIRAGA, Shigeru SUGANO
    Type: Review Article
    Volume 27 (2016) Issue 2 Pages 37-48
    Released: June 21, 2016
    JOURNALS FREE ACCESS
    After publication of the epic report on equine exercise physiology by Matsuba and Shimamura in 1933, papers on exercise physiology of the racehorse in Japan began appearing in scientific journals and increased in number. In 1944, respiration during exercise at a walk, trot, and canter was measured by recording expiratory sounds with a microphone attached near the nostril. Respiratory frequency during cantering was synchronized with stride frequency, and expiratory sounds were found to occur during the stance phase of the trailing forelimb. Development of a radiotelemetry system in 1964 for electrocardiogram recording enabled the first recording of an equine electrocardiogram during field exercise that included fast galloping and calculation of heart rate (HR) during exercise. During low intensity exercise including walking, trotting, cantering and extended cantering, HR increased from 45 beat/min during pre-exercise to 150 beat/min at an extended canter. HR increased to 200 beat/min or more in most horses during 100 m of high-intensity sprint galloping. When blood lactate was measured after 3 days of draft work in 12 warhorses in 1934, no increase in blood lactate was found. The erythrocyte sedimentation rate (ESR) was decreased by intense exercise and also decreased as training increased. It was suggested that measuring changes in ESR and body weight in relation to training might become useful as a screening index of training, condition, and fatigue. This evaluation method was named the “ESR-body weight method.”
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Original Article
  • J.L. EDMUNDS, H.J. WORGAN, K. DOUGAL, S.E. GIRDWOOD, J.-L. DOUGLAS, N. ...
    Type: Original Article
    Volume 27 (2016) Issue 2 Pages 49-55
    Released: June 21, 2016
    JOURNALS FREE ACCESS
    The present study uses in vitro analytical techniques to investigate the effect of activated charcoal on the microbial community of the equine hindgut and the metabolites they produce. Incubations were performed in Wheaton bottles using a 50 ml incubation of a high-energy feed or a low-energy feed, plus bottles with no added food source, together with five levels of activated charcoal (0, 10, 25, 50 or 100 mg per bottle) and fecal samples as a bacterial inoculum. Using this method the rate of gas production, volatile fatty acid and ammonia concentrations, and pH values were analyzed and found to vary depending on the addition of feed, but the activated charcoal had no effect (P>0.05) on any of these. It is already believed that the effect of activated charcoal as a control for toxic substances is at its highest in the foregut or midgut of animals, and therefore should have little impact on the hindgut. The data presented here suggest that if any of the activated charcoal does reach the hindgut, then it has no significant impact on the microbial community present, nor on the major metabolites produced, and so should not have a detrimental effect on the principal site of fermentation in the horse.
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  • Daiki MURATA, Atsushi YAMASAKI, Shouta MATSUZAKI, Takafumi SUNAGA, Mak ...
    Type: Original Article
    Volume 27 (2016) Issue 2 Pages 57-65
    Released: June 21, 2016
    JOURNALS FREE ACCESS
    Dedifferentiated fat (DFAT) cells have been shown to be multipotent, similar to mesenchymal stem cells (MSCs). In this study, we aimed to establish and characterize equine DFAT cells. Equine adipocytes were ceiling cultured, and then dedifferentiated into DFAT cells by the seventh day of culture. The number of DFAT cells was increased to over 10 million by the fourth passage. Flow cytometry of DFAT cells showed that the cells were strongly positive for CD44, CD90, and major histocompatibility complex (MHC) class I; moderately positive for CD11a/18, CD105, and MHC class II; and negative for CD34 and CD45. Moreover, DFAT cells were positive for the expression of sex determining region Y-box 2 as a marker of multipotency. Finally, we found that DFAT cells could differentiate into osteogenic, chondrogenic, and adipogenic lineages under specific nutrient conditions. Thus, DFAT cells could have clinical applications in tissue regeneration, similar to MSCs derived from adipose tissue.
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  • Daisuke MIYAKOSHI, Hiroyuki SENBA, Mitsumori SHIKICHI, Masaya MAEDA, R ...
    Type: Original Article
    Volume 27 (2016) Issue 2 Pages 67-76
    Released: June 21, 2016
    JOURNALS FREE ACCESS
    This study aimed to evaluate the influence of radiographic abnormalities of 2-year-old Thoroughbred horses that were listed at in-training sales in Japan, on whether they started to race or not at 2–3 years of age. Radiographs of 850 2-year-old Thoroughbreds in the in-training sales repository from 2007 to 2010 were reviewed, and 26 categories of radiographic abnormalities were found. Forty-three horses (5.1%, 43/850) did not start a race at 2–3 years of age. In accordance with the racing results for this age category, as determined by Fisher’s exact test and multiple logistic regression analysis, none of the radiographic abnormalities were significantly related to failure to start a race. At 2 years of age, 198 horses (23.3%, 198/850) did not start a race. Horses with enlargement of the proximal sesamoid bones in the fore (9 of 19 horses) and hind limbs (5 of 9 horses) did not start a race at the age of 2 years, and fewer of these horses (fore, P=0.021; hind, P=0.030) started a race at the age of 2 years compared with the population of horses without these radiographic abnormalities. These results suggest that identification of radiographic enlargement of the proximal sesamoid bones during training sales could derail the racing debut of horses at the age of 2 years. However, this might not necessarily indicate a poor prognosis and resulting in retirement from racing at 2–3 years of age.
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Note
  • Nao TSUZUKI, Naoki SASAKI, Kanichi KUSANO, Yoshiro ENDO, Shidow TORISU
    Type: Note
    Volume 27 (2016) Issue 2 Pages 77-79
    Released: June 21, 2016
    JOURNALS FREE ACCESS
    Oxidative stress has been reported to occur during surgery. It is important to reduce intraoperative oxidative stress to improve the postoperative prognosis. However, there are no reports regarding oxidative stress related to surgery in horses. In the present study, we measured pre and postsurgical diacron-reactive oxygen metabolites (d-ROMs) and biological antioxidant potential (BAP); the oxidative stress index (OSI) was then calculated (OSI=d-ROMs/BAP × 100). d-ROMs were not significantly different between the pre and postsurgical periods. However, BAP significantly decreased after surgery (P=0.02), and OSI significantly increased after surgery (P=0.02). Based on these results, it suggested that castration surgery under inhalation anesthesia decreases the antioxidant potential and causes oxidative stress in horses.
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