Journal of Equine Science最新文献

We investigated the changes in inbreeding levels in Japanese Thoroughbred horses over the past 46 years. Our results show a significant increase in inbreeding over the past 30 years, primarily due to the influence of two sires, Northern Dancer and Sunday Silence. Northern Dancer's bloodline spread gradually through descendants like Northern Taste, leading to a slower increase in the inbreeding coefficient. In contrast, Sunday Silence was directly imported and became a leading sire, causing a rapid increase in his blood proportion and inbreeding coefficient. Our findings suggest that monitoring the trajectories of successful sires and considering historical factors can help predict and control potential inbreeding depression in the future.

Including Internet of Things (IoT) technology in horse-rearing management can potentially mitigate problems such as human resource shortages and time limitations in performing daily behavior monitoring. In this study, a small and inexpensive activity meter used to monitor dogs and cats (PLUS CYCLE^®, JARMeC, Kanagawa, Japan) was used to monitor the daily behavior of horses. A study was performed to examine the suitability of the PLUS CYCLE^® device for monitoring horses and to determine whether it could estimate horse behavior. The device was equipped with an accelerometer and was used to monitor Kiso horses in horse stalls and pastures after installing the devices at specific locations on headcollars and girths. The amount of activity from the accelerometer showed differences among the horses' behavioral types (lying, standing, walking, and feeding) in the stall, suggesting that it functions in horses. In the pasture, the amount of activity was correlated with GPS movement speed. Then, we tried to establish restricted cubic spline regression models to predict the locomotion speed in the pasture based on the amount of activity, but the prediction accuracy was low. This study showed that PLUS CYCLE^® can be used to monitor horse activity amount during the daily management of individual horses. However, to achieve higher precision in monitoring detailed behaviors, additional investigation and data pertaining to the amount of activity for each horse during rearing in different environments are needed.

A two-year-old male Japanese draft horse (known as a "Ban'ei horse") excreted eight cestodes. Based on their morphological features, they were identified as Anoplocephala perfoliata. The partial mitochondrial cytochrome c oxidase subunit 1 (COI) sequences of the worms were nearly identical to A. perfoliata isolated from horses in Europe. The results of phylogenetic analyses of COI revealed that our samples and the European isolates formed the same clade, which was separate from Chinese and Australian isolates. Ban'ei horses were developed by crossbreeding draft horses imported from European countries in the 1900s. Our results suggest that A. perfoliata was transported to Hokkaido with horses from Europe. To our knowledge, this is the first report of A. perfoliata infection in a Japanese draft horse.

We evaluated the clinical efficacy of total intravenous anesthesia (TIVA) with propofol-ketamine-xylazine (PKX) with or without remifentanil for castration in horses. Twenty-four Thoroughbred horses were premedicated with intravenous (IV) xylazine (1.0 mg/kg) and midazolam (0.02 mg/kg) and anesthetized with IV ketamine (1.5 mg/kg) and propofol (1.0 mg/kg). Surgical anesthesia was maintained with constant infusion of propofol (3.0 mg/kg/hr)-ketamine (3.0 mg/kg/hr)-xylazine (1.0 mg/kg/hr) (group PKX: n=8), PKX combined with remifentanil (3.0 µg/kg/hr) (group PKXR3: n=8), or PKX combined with remifentanil (6.0 µg/kg/hr) (group PKXR6: n=8). During anesthesia, none of the horses showed any limb movements, but five, two, and two horses in the PKX, PKXR3, and PKXR6 groups, respectively, showed cremaster muscle contractions. One horse in the PKX group required doubling the PKX infusion rate to continue surgery. Adverse effects of remifentanil (trembling of the nose tip or tongue) were observed in one and three horses in the PKXR3 and PKXR6 groups, respectively. Heart rate and arterial blood pressure were well maintained in all groups. Ventilation was assisted in four, five, and six horses in the PKX, PKXR3, and PKXR6 groups, respectively. Recovery scores in the PKX group were fair in one horse, good in three horses, and excellent in four horses, whereas recovery in all horses in the PKXR3 and PKXR6 groups was judged to be excellent. TIVA with PKX combined with remifentanil 3.0 µg/kg/hr could provide more sufficient anesthetic depth than PKX with fewer clinically significant adverse effects than that with remifentanil 6.0 µg/kg/hr.

Osteoarthritis (OA) is a prevalent condition in horses, leading to changes in trabecular bone structure and radiographic texture. Although fractal dimension (FD) and lacunarity have been applied to quantify these changes in humans, their application in horses remains nascent. This study evaluated the use of FD, bone area fraction (BA/TA), and lacunarity in quantifying trabecular bone differences in the proximal phalanx (P1) in 50 radiographic examinations of equine metacarpophalangeal joints with varying OA degrees. In the dorsopalmar view, regions of interest were defined in the trabecular bone of the proximal epiphysis, medial and lateral to the sagittal groove of P1. Lower BA/TA values were observed medially in horses with severe OA (P=0.003). No significant differences in FD and lacunarity were found across OA degrees (P>0.1). FD, BA/TA, and lacunarity were not effective in identifying radiographic texture changes in the P1 trabecular bone in horses with different metacarpophalangeal OA degrees.

A horse's body condition impacts every aspect of its life, including reproduction, performance, and health. Obesity and equine metabolic syndrome (EMS) are common in Nigeria; hence, early identification of a horse's obesity status by the owner is key to avoiding associated health issues such as EMS. Our study aimed to determine whether horse owners could effectively estimate their horses' body condition scores (BCSs) and cresty neck scores (CNSs). A total of 50 adult sedentary West African Barb horses owned by 50 different people were enrolled in the study. Body condition scores (BCSs) and cresty neck scores (CNSs) were assessed on scales of 1-9 and 0-5, respectively, by an experienced veterinarian and owners. The latter had no veterinary background, received no prior education, and assessed their horses based on provided visual aids and descriptions. The BCS estimates of the experienced veterinarian and owners were slightly in agreement (k=0.209), while there was moderate agreement (k=0.547) between the CNS estimates of the experienced veterinarian and the owners. The proportion of obesity based on the experienced veterinarian's estimation (32%) was higher than that of the owners (18%). The proportion of nuchal crest adiposity based on the experienced veterinarian's (38%) estimation was slightly lower than that of the owners (42%). A larger proportion of the owners underestimated their horses' BCSs and CNSs. We conclude that owners cannot effectively estimate their horses' BCSs and CNSs. It is imperative that they are informed about the health issues associated with obesity and are taught how to effectively estimate BCS and CNS.

Equine testicular arteritis commonly occurs as a consequence of the migration of nematode larvae or equine arteritis virus (EAV) infection. However, testicular arteritis without evidence of these infections has been reported, and the underlying pathogenesis remains unclear. We encountered testicular arteritis without evidence of nematode or EAV infection in a 3-year-old male heavy draft horse with scrotal enlargement. Grossly, the volume of the pampiniform plexus was markedly increased due to edema. Histologically, non-suppurative and necrotizing testicular arteritis, characterized by lymphocyte infiltration and fibrinoid necrosis of the arterial walls, was diffusely observed in the spermatic cord, pampiniform plexus (most severe), testis, and epididymis. We were unable to identify the cause of arteritis, such as a viral infection or autoimmune abnormality.

Although there have been advances in the technology for measuring horse body size with stereoscopic three-dimensional (3D) scanners, previously reported methods with a single scanner still face a significant challenge: the time necessary for scanning is too long for the horses to remain stationary. This study attempted to scan the horse simultaneously from four directions using four scanners in order to complete the scans in a short amount of time and then combine the images from the four scans on a computer into one whole image of each horse. This study also compared body measurements from the combined 3D images with those taken from conventional manual measurements. Nine riding horses were used to construct stereoscopic composite images, and the following 10 measurements were taken: height at the withers, back, and croup; chest depth; width of the chest (WCh), croup, and waist; girth circumference, cannon circumference (CaC), and body length. The same 10 measurements were taken by conventional manual methods. Relative errors ranged from -1.89% to 7.05%. The correlation coefficient between manual and 3D measurements was significant for all body measurements (P<0.01) except for WCh and CaC. A simple regression analysis of all body measurements revealed a strong correlation (P<0.001, R²=0.9994, root-mean-square error=1.612). Simultaneous scanning with four devices from four directions reduced the scanning time from 60 sec with one device to 15 sec. This made it possible to perform non-contact body measurements even on incompletely trained horses who could not remain stationary for long periods of time.

Plasma or serum amino acids are used to evaluate nutritional status and metabolic disorders. In this study, we aimed to set reference values of serum amino acid concentrations in the Noma horse, a Japanese native horse. Thirty-one horses were classified into six age groups: neonatal foal (0-4 days), foal (0.5-1 years), youth (5 years), middle age (10 years), old (15 years), and extra-old (>20 years). Horses >5 years of age were analyzed together as the adult group. In the adult horses, there were no significant differences among the serum amino acid concentrations of each age group. The foal group had higher concentrations of alanine, aspartic acid, glutamic acid, α-aminoadipic acid, and 3-methyl-histidine than the adult group. The neonatal foal group had higher serum concentrations of phenylalanine, lysine, alanine, proline, aspartic acid, glutamic acid, β-alanine, and β-amino-iso-butyric acid and lower tryptophan concentrations and Fischer's ratios than the adult group. The neonatal foal group had higher β-amino-iso-butyric acid concentrations and lower tryptophan and 3-methyl-histidine concentrations than the foal group. Therefore, reference values might be set separately in neonatal foals, foals, and adult horses. The data for the serum amino acid concentrations can be used for health care through physiological and pathological evaluations in Noma horses.

A pharmacokinetic/pharmacodynamic (PK/PD) approach was used to determine a dosage regimen of cephalothin (CET) after intramuscular (IM) administration in horses. CET plasma concentrations were measured in eight horses after a single IM administration of 11 mg/kg bwt of CET. The data were modeled using a nonlinear mixed-effect model, and the probability of target attainment (PTA) of the PK/PD target was calculated for 5,000 horses generated by Monte Carlo simulations. IM administrations of CET at 11 mg/kg bwt q 8 hr and q 6 hr achieved a PTA of 90% against the MIC₉₀ of S. zooepidemicus and S. aureus, respectively, and were considered to be effective dosage regimens. The total dose for the IM administration recommended in this study was lower than that for intravenous (IV) administration in previous studies.