Journal of Equine Science最新文献

This study aimed to evaluate the effects of packing (load carrying) on the diurnal rhythms of respiratory and heart rates in donkeys during the hot-dry season. Twenty 2- to 3-years-old donkeys weighing 93 ± 2.7 kg were divided into two groups to serve as subjects: Group 1 was subjected to packing + trekking, while group 2 was subjected to trekking only. All donkeys trekked 20 km on each experimental day. The procedure was repeated three times at one-day intervals. Thermal environmental parameters were recorded. Respiratory rate (RR) and heart rate (HR) were measured before and immediately (15 min) after the packing and/or trekking period. Continuous recordings of parameters were performed for 27 hr at 3-hr intervals beginning 16 hr after the last packing and/or trekking period. The RR rose significantly (P<0.05) immediately after packing + trekking and trekking only, from 30.15 ± 0.5 and 27.52 ± 0.5 cycles/min before packing + trekking and trekking only, respectively, to 43.78 ± 3.0 and 46.30 ± 1.8 cycles/min after them, respectively. The HR (76.63 ± 4.5 beats/min) in the packing + trekking donkeys was higher (P<0.05) than that of the trekking-only donkeys (62.33 ± 2.7 beats/min). The acrophase and bathyphase of the HR in both groups were recorded during the photophase and scotophase, respectively, with higher values (P<0.05) in the packing + trekking donkeys than in the trekking-only donkeys. The circadian rhythms of RR and HR did not differ between the groups of donkeys. In conclusion, packing + trekking was more stressful to the donkeys, significantly increasing the HR of donkeys subjected to packing + trekking, compared with trekking only.

The Taishu horse in Tsushima is one of eight Japanese native breeds. The breed is on the verge of extinction due to a rapid decrease in numbers since the 1960s owing to motorization in Japan. In this study, we aimed to confirm the pedigree information of 52 horses by genotyping 31 microsatellites in order to avoid inbreeding. Parentage verification failed to identify genetic contradictions among trios (sires, dams, and foals) registered with the Japan Equine Affairs Association (JEAA). Pedigree information registered at the JEAA was obtained and adequately understood. Additionally, the genetic diversity of the Taishu horses was evaluated and compared with those of other Japanese native breeds. The average values for the number of alleles, observed heterozygosity, expected heterozygosity, and inbreeding coefficient were 4.7, 0.643, 0.632, and -0.02, respectively. Using the Structure software, the 52 horses were classified into three subgroups based on the individuals with more than 50% of specific genetic components. The phylogenetic trees created based on neighbor-joining classification tended to be consistent among the stallions. The effective population size was 27.5 and lower than that required for maintaining 90% genetic variation in the source population over a period of 100 years (47.5). Compared with the other Japanese breeds, the Taishu horse population included in the current study exhibited moderate genetic diversity. Our study will contribute to reconsideration of the breeding strategy of Taishu horses.

Vitamin D requirements for most animals are expected to be fulfilled through daily exposure of the skin to solar ultraviolet B radiation. The synthesis of vitamin D₃ in skin depends on different factors including melanin pigmentation, the amount of UVB radiation reaching the skin, type of clothing/hair coat, latitude and altitude, season, and time of day. Alternatively vitamin D₂ may be obtained from UVB irradiated pasture species. Recent studies have shown that in unsupplemented grazing horses 25-hydroxyvitamin D₂ is the predominant form of vitamin D in plasma, and that 25OHD₃ is undetectable suggesting horses may rely on diet to obtain vitamin D. In order to mimic the natural environment of skin to sunlight exposure, five equine and two ovine devitalized skin samples were irradiated with 5 J/cm² of UVB light followed by measurement of 7-dehydrocholesterol (7-DHC) and vitamin D₃ concentrations using reverse-phase high pressure liquid chromatography (HPLC). HPLC revealed the presence of 7-DHC in the skin of both horses and sheep. Vitamin D₃ was undetectable in both ovine and equine skin prior to irradiation, but after irradiation with UVB light, ovine skin showed an increase in vitamin D₃ concentration (mean 0.16 ± 0.07 µg/g), whereas vitamin D₃ was undetectable in equine skin. These results provide additional evidence that horses make negligible quantities of vitamin D₃ in their skin after exposure to UVB light and may therefore rely on their diet as a primary source of vitamin D.

Indisputably, the use of antivenoms for the treatment of snakebite envenoming is beneficial for the victims. However, there are few studies addressing the effect of long-term hyperimmunization in inoculated horses. It is known that the injection of snake venoms and adjuvants leads to local and systemic reactions in horses, but little is known about the response of inflammatory proteins. The aim of this study was to evaluate serum proteins and the electrophoretic profile of horses undergoing crotalid venom hyperimmunization. Twenty horses were divided into two groups: an inoculated group, comprising ten horses that were already being used for production of a Crotalus sp. antivenom, and a control group, comprising ten animals that had never been used for hyperimmunization. All animals were clinically healthy and without laboratory abnormalities. Total protein and albumin concentrations were measured in serum. Serum globulins were obtained by calculation. Plasma fibrinogen estimates were determined by the heat precipitation method. Serum proteinograms were obtained using agarose gel electrophoresis. The results revealed a significant increase in the concentrations of total serum proteins, globulins, and β-globulins in the inoculated group, exceeding the reference values. There were slight increases in the α-1- and α-2-globulin subfractions in serum-producing horses, with no statistical significance. We also observed that horses used to produce hyperimmune plasma developed hypoalbuminemia, although the decrease in albumin production was not statistically significant. Our findings suggest that the continuous use of horses to produce crotalid antivenom may lead to a chronic inflammatory stimulus, with changes in plasma levels of inflammatory proteins.

Cephalothin (CET) concentrations in body fluids (plasma, synovial fluid, pleural fluid, peritoneal fluid, and aqueous humor) and tissue samples (bone, lung, jejunum, hoof, and subcutaneous tissue) were investigated to consider the treatment of infectious diseases in horses. CET 22 mg/kg body weight was intravenously administered to 12 horses. Samples were collected from four different horses at 1, 3, and 5 hr after administration. The CET concentration in body fluids other than aqueous humor was maintained above the MIC₉₀ values of Streptococcus zooepidemicus and Staphylococcus aureus until 5 hr, but it was not maintained above that of S. aureus in bone. CET (22 mg/kg twice a day) is effective for septic arthritis, pleuritis, and peritonitis caused by gram-positive bacteria but ineffective for osteomyelitis.

The objective of this study is to analyze the relationships between the age and blood test results or body sizes in Noma horses by using the results of periodical health examination. Out of 45 hematological or physical items examined, statistically significant, but loose correlations were observed in 14 items. Red blood cell count, activities of aspartate aminotransferase, alkaline phosphatase, and creatinine kinase, concentrations of calcium and inorganic phosphorus decreased with aging. Conversely, mean corpuscular volume, mean corpuscular hemoglobin, lipase activity, γ-globulin and chloride concentrations, body height, chest circumference and cannon bone circumference increased with aging. The changes in a few items seemed unique to Noma horse. However, most age-related changes found in this study might be considered as a common trend in horse breeds rather than distinctive characteristic in Noma horse.

The Wingless and Int-1 (WNT) and bone morphogenic protein/growth differentiation factor (BMP/GDF) signalling pathways contribute significantly to the development of the musculoskeletal system. The mechanism by which they contribute is as follows: BMP/GDF signalling usually promotes tendon differentiation, whereas WNT signalling inhibits it. We hypothesised that inhibiting WNT and subsequently stimulating BMP signalling may enhance the tenogenic differentiation of stem cells. The objective of this study was to determine whether a combination of WNT inhibitor (KY02111) and BMP12/GDF7 protein could enhance the differentiation of bone marrow-derived equine mesenchymal stromal cells (BM-eMSCs) into tenocytes. Cells were cultured in five treatments: control, BMP12, and three different combinations of BMP12 and KY02111. The results indicated that a 1-day treatment with KY02111 followed by a 13-day treatment with BMP12 resulted in the highest tenogenic differentiation score in this experiment. The effect of KY02111 is dependent on the incubation time, with 1 day being better than 3 or 5 days. This combination increased tenogenic gene marker expression, including SCX, TNMD, DCN, and TNC, as well as COL1 protein expression. In conclusion, we propose that a combination of BMP12 and KY02111 can enhance the in vitro tenogenic differentiation of BM-eMSCs more than BMP12 alone. The findings of this study might be useful for improving tendon differentiation protocols for stem cell transplantation and application to tendon regeneration.