Journal of Equine Veterinary Science最新文献

Equine insulin dysregulation (ID) is a significant metabolic problem because the hyperinsulinaemia that develops increases the animal's risk of developing laminitis, a debilitating foot condition. The role of gastrointestinal factors, such as incretin hormones, in the pathogenesis of ID and hyperinsulinaemia in horses is poorly understood, particularly in comparison to other species. Glucagon-like peptide-2 (GLP-2) is an intestinotrophic peptide released from L cells in the gastrointestinal tract and is implicated in metabolic dysfunction in other species. The aim of this study in vitro was to establish basic physiological understanding about intestinal secretion of GLP-2 in horses. Basal and glucose-stimulated GLP-2 secretion was measured in post-mortem tissue samples from the duodenum, jejunum, and ileum. We observed that GLP-2 secretion was minimal in samples from the duodenum compared to the jejunum and ileum (5-9-fold higher; P < 0.05). Furthermore, GLP-2 secretion was not responsive to glucose stimulation in the ileum or duodenum but was responsive to glucose in the jejunum. This effect in the jejunum was inhibited by 30 % (P = 0.02) using phlorizin, a selective sodium-glucose cotransporter-1 (SGLT-1) inhibitor, and by 38 % (P = 0.04) using phloretin, a non-selective SGLT-1/GLUT-2 inhibitor. The localisation of glucose-responsive GLP-2 secretion in the jejunum might be relevant to the development of post-prandial hyperinsulinaemia. This study has provided data on GLP-2 secretion from the equine small intestine that will enable more complex and dynamic studies on the pathogenesis of ID.

A 4.5-month-old Standardbred colt presented for neck swelling and fever. Endoscopy and contrast radiography identified a full thickness esophageal perforation. Surgical intervention with fasciotomies and placement of an esophageal feeding tube was elected. Intensive postoperative treatment was carried out with broad-spectrum antibiotics, gastroprotectants and probiotics, calculated feeding plan, esophagostomy and fasciotomy site lavages, care, and cleaning. Complications included recurrent bilateral pneumothorax and development of an incomplete fistula at the esophagostomy site following removal of the feeding tube, necessitating primary closure. One year following presentation, the colt appears to have made a full recovery with an excellent body and muscle condition score and undergoing athletic training. Anticipated price of sale as a yearling was achieved. This study highlights a viable treatment route for youngstock with esophageal perforation that necessitate an esophagostomy. Despite intensive dietary needs of growing foals, appropriate nutritional requirements and normal growth rates can be achieved in such cases.

The equine digital cushion (DC) has been a poorly understood structure regarding its mechanical properties and composition. The objective of this study was to develop a sampling technique and to compare the biomechanical and histologic properties of DC between lame and non-lame forelimbs. Both forefeet from horses with induced carpal lameness were radiographed prior to humane euthanasia. Radiographs were used to guide sample collection of two, post-mortem, midline DC samples, palmar and dorsal, via an 8mm biopsy punch. Samples were subjected to compressive testing to determine elastic modulus. Histological evaluation was used to quantify collagen, adipose, ground substance, elastic fibers, and blood vessels. Comparisons of variables between palmar and dorsal DC sites and lame and non-lame limbs were made using student's t-tests or Wilcoxon signed rank tests with P < 0.05. There were no differences in histologic or biomechanical properties in DCs of lame and non-lame forelimbs. The dorsal DC sampling site had a significantly higher median elastic modulus (median: 0.054 MPa, range: 0.001 – 2.110 MPa) and a larger median percentage of ground substance (median: 15 %, 95 % CI: 3 – 30 %) compared to the palmar DC site (elastic modulus: median: 0.023 MPa, range: 0 – 0.576 MPa; ground substance: median 5 %, 95 % CI: 3 – 25 %) (P = 0.03, <0.001; respectively). This study demonstrated that adequate samples could be collected from the DC for biomechanical and histological analysis. Differences in elastic modulus and ground substance between palmar and dorsal samples may reflect different roles of these sites within the DC.

In international equestrian sport, visual inspections assess gait and lameness to protect the welfare of performance horses during competition. Horses competing internationally in three-day eventing must pass two mandatory inspections (pre-competition and post-cross country) before attempting the final phase: the jumping test (JT). We hypothesized that digitally quantifying objective gait parameters captured during the two mandatory inspections will identify locomotor characteristics that predict success during the jumping test. Utilizing the DeepLabCut (DLC) software package for labeling of anatomical landmarks and a custom analysis pipeline we calculated gait parameters for 194 competition horses at the trot. During the pre-competition inspection, relative trot speed was significantly associated (P = 0.0060, GLMM), and the forelimb travel trended towards significance (P =0.0800, GLMM), with achieving a clear round in the later jumping test. Post-cross country, the forelimb travel significantly predicted JT results (P = 0.0188, GLMM). As our parameters are scaled for body size, these parameters may indicate conformational characteristics for superior jumping ability and overall athletic fitness. Within each competitive effort, comparisons of the post-cross country and pre-competition observations revealed that the change in speed and duty factor were significantly different in the group that accrued jumping faults (P = 0.00376 and P = 0.02430, GLMM), perhaps capturing locomotor signs of exercise fatigue. Further work employing these approaches to better understand competition performance will encourage the use of objective measures to protect sport horse welfare, as well as provide an advantageous tool for gait evaluation in the horse.

Indoor arenas do not always include mechanical ventilation or stirring fans and occupancy by horses and humans can be sporadic and inconsistent, which creates a challenging space for understanding and predicting variations in temperature, moisture, and airflow. To understand the interior environment within indoor arenas, monitoring was conducted at 15 facilities within 200 kilometres of Lexington, KY. Environmental monitoring of dry bulb temperature, relative humidity, dew point temperature, air speeds, and solar radiation took place over 7 days in the winter and summer to examine temporal variability. Environmental data was collected every 5 minutes using the HOBO RX3000 Remote Monitoring Station with the HOBOnet Temp/RH Sensor, HOBOnet Solar Radiation (Silicon Pyranometer) Sensor, and HOBOnet Ultrasonic Wind Speed and Direction Sensor. Clear seasonal differences and diurnal patterns were evident in all environmental conditions, but the relative humidity. The relative humidity and dew point temperatures indicated moisture could be an issue in many of the indoor arenas. High relative humidity and excess moisture can negatively impact horse and human health as well as the lifespan of the facility. Similar results to previous spatial variability indoor arena characterizations were observed during the environmental monitoring with air speeds being below the threshold for still air in livestock facilities (0.51 m s^-1). Sensor technology and implementation provides a better understanding of the interior environment and how indoor arena design can impact it.

This study aimed to investigate the effect of mitochondria-targeted antioxidants (Mitoquinone, MitoQ) on the quality of frozen-thawed stallion semen. Semen samples collected from three fertile stallions aged 10 - 13 years, were filtered, centrifuged in a skimmed milk-based extender, and diluted to a final concentration of 50 × 106 sperm/mL in freezing medium. Diluted semen was divided into five experimental groups supplemented with MitoQ at concentrations of 0 (control), 25, 50, 100, and 200 nM and then subjected to freezing after cooling and equilibration. After thawing, semen was evaluated for motility and kinetics at different time points. Sperm viability, plasma membrane, acrosome, DNA integrity, mitochondrial membrane potential, apoptosis, and intracellular reactive oxygen species (ROS) concentrations were evaluated. The results revealed that MitoQ at concentrations of 25, 50, and 100 nM improved (P< 0.01) the total sperm motility after 30 minutes of incubation. In addition, 25 nM MitoQ improved the sperm amplitude of lateral head displacement values (P< 0.01) after 30 minutes of incubation. Conversely, negative effects on sperm motility, kinetics, and viability were observed with the highest tested concentration of MitoQ (200 nM). The various concentrations of MitoQ did not affect the plasma membrane, acrosome, and DNA integrity, or the mitochondrial membrane potential and intracellular ROS concentrations. In conclusion, supplementation of MitoQ during cryopreservation, had a mild positive effect on sperm motility and kinetics especially at a concentration of 25 nM, while the highest concentration (200nM) has a detrimental effect on motility and viability parameters of frozen-thawed stallion sperm.

Historically, 8 × 0.5 ml straws, containing approximately 800 million sperm and 250 million progressively motile sperm were provided as a single ‘breeding dose’ of cryopreserved stallion semen. With the use of deep horn artificial insemination, there is a trend to reduce the number of 0.5 ml straws sold as a breeding dose, sometimes down to as little as one straw. Our aims were to determine if the number of straws provided as a breeding dose, as well as other mare, stallion and management factors, have an impact on pregnancy outcome in mares inseminated with cryopreserved semen. Unexpectedly, we identified no effect of the number of 0.5 ml straws on pregnancy outcome. We also identified no difference in pregnancy outcome for those mares inseminated once post-ovulation compared to mares inseminated once pre- and once post- ovulation. Additionally, for mares inseminated once post-ovulation, we identified no benefit of breeding 0-3 hours post-ovulation vs. breeding 0-6 hours post-ovulation. Other factors not associated with pregnancy outcome included: whether an endometrial sample was obtained for bacteriologic culture, whether the endometrial sample produced bacterial growth, whether a mare developed fluid after breeding, whether a mare was treated for bacterial endometritis and/or uterine fluid, and post-thaw progressive sperm motility. These results suggest the existence of an effective industry self-selection process in which only semen from the most fertile stallions is marketed in these ‘ultra-low’ doses and that breeding mares within 3 hours post- ovulation provides no benefit to pregnancy outcome compared to breeding mares within 6 hours post-ovulation.

Transrectal and transabdominal ultrasonography is an established method to monitor pregnancy, fetal growth and wellbeing in different species. Growth charts with multiple bio-morphometric parameters to estimate days of gestation and days before parturition exist in small companion animals, sheep and goats, riding type horses and large ponies but not in small horse breeds like Shetland ponies. The aim of this study was to apply fetal biometric assessment and detailed description of physiologic fetal development to mid and late term pregnancies in Shetland mares and to generate reference data for clinical practice and for future research. Fetal parameters were collected starting on day 101 of pregnancy in five Shetland mares. The fetal biometric parameters determined consisted of aortic diameter, eye diameter, combined rib and intercostal distance (CRID), stomach length and width and different heart morphology parameters in sagittal and frontal plane. Additionally, fetal activity and organ development in terms of differentiation and changes in echogenicity were recorded. Considering reliably assessable parameters, fetal CRID was the best predictor for gestational age with ± 13.6 days and fetal aortic diameter the most accurate for prediction of days until parturition with ± 16.2 days.

Endometritis is the leading cause of mare subfertility. Most mares respond to standard therapy, but alternative therapies have been developed for mares failing to respond. This study aimed to investigate a commercially available, yet unassessed, product labeled as a uterine sanitizer to determine the in vitro antimicrobial activity against microorganisms associated with endometritis and its in vitro stability to dilute antibiotics. In experiment 1, the microdilution broth technique and antimicrobial effects were assessed against Escherichia sp, Staphylococcus sp., Klebsiella sp., Pseudomonas sp., and Candida sp. Percentage inhibition was calculated by comparing the optical density. The minimum inhibitory concentration (MIC) 100% was determined using the resazurin dye technique. MIC 50% and 90% were determined using a dose-response non-linear regression. In experiment 2, the uterine sanitizer was used to dilute commonly used antibiotics achieving a final volume of 90 mL at 5°C, 21°C, and 37°C. The pH was measured at 0, 1, 3, 6, and 24 h after dilution. The uterine sanitizer had inhibitory properties against all microorganisms; Escherichia sp. being the most susceptible, and Pseudomonas sp. the most resistant. The uterine sanitizer had an acidic pH=4; however, when combined with the antibiotics, the pH of the antibiotic remained unchanged with the different temperatures and did not precipitate. In conclusion, the uterine sanitizer showed antimicrobial effects against endometritis-causing microorganisms. The dilution of antibiotics in the uterine sanitizer was stable and this association could potentiate the antimicrobial effects. Uterine sanitizer's safety and clinical efficacy in vivo remain to be tested.