Effect of Exercise in a Vector-Protected Arena for Preventing African Horse Sickness Transmission on Physiological, Biochemical, and Behavioral Variables of Horses.

During an African horse sickness (AHS) outbreak, horses were able to exercise daily in a net-covered arena, yet the physiological responses to exercise in a netted arena was unknown. In a cross-over study design, eight horses performed a 39-minute aerobic exercise in conventional (CA) and vector-protected arenas (VPA). Horses were slower in some gaits and covered less distance in the VPA arena (P < .01). Cortisol release, hematology, and heart rate variability (HRV) were also examined. An interaction between the riding arena and time was observed in hematocrit (P = .0013), hemoglobin (P = .0012), and red blood cell count (P = .0027) and HRV variables, including mean beat-to-beat (RR) intervals (P < .0001), mean heart rate (P < .0001), sympathetic nervous system (SNS) index (P = .0038) and parasympathetic nervous system (PNS) index (P < .0001). Cortisol concentrations increased during exercise and 30 minutes postexercise in both arenas. Hematocrit, hemoglobin, and red blood cell count increased immediately postexercise in horses in VPA while remaining high from immediate post-exercise to 60 minutes postexercise in horses in CA. HRV decreased during exercise and was not different between horses in both arenas, but a higher RR interval and PNS index, corresponding to lower heart rate and SNS index, were detected during 30 to 60 minutes postexercise in horses in the VPA compared to the CA. Riding horses in different arenas impacted hematological and HRV variables. The greater RR intervals and PNS index, coinciding with the lower SNS index and heart rate, indicated parasympathetic dominance post-exercise in horses in VPA compared to CA.

Influence of full-time housing in vector-protected facilities on equine cortisol levels, heart rate, and behavior during the African horse sickness outbreak in Thailand.

Horses were provided full-time housing in unfamiliar vector-protected facilities during the African horse sickness (AHS) outbreak in Thailand. This study aimed to investigate the impact of this housing arrangement on the equine stress response. Nine healthy horses were housed in both a traditional barn and a vector-protected barn. Equine behavior and stress response data were collected in association with the housing environment and time of day. The mean behavioral score of horses housed in the vector-protected barn was lower at night than during the day. In addition, the horses' mean heart rate at night was lower than their heart rate during the day, irrespective of housing condition. Furthermore, although blood cortisol peaked at 6:00 AM and was lowest at 6:00 PM under both housing conditions, daily fluctuations in blood cortisol levels were correlated with changes in humidity and temperature in both environments. Finally, horses housed in the traditional barn exhibited earlier decreases in cortisol levels relative to the horses in the vector-protected barn. This result indicates that housing horses in vector-protected facilities may impose stress.

The impact of strategic ventilation adjustments on stress responses in horses housed full-time in a vector-protected barn during the African horse sickness outbreak in Thailand.

The severe outbreak of African horse sickness (AHS) in Thailand has forced horses to reside full-time inside barns that are covered by a small mesh net to prevent minuscule AHS insect vectors from gaining access. However, housing in the net-covered barn induces stress in horses, which compromises their welfare. Implementing strategic airflow adjustment while retaining the vector-protection characteristics has been proposed to help alleviate this problem. The present study aimed to investigate the effect of strategic ventilation adjustment on blood cortisol levels, heart rate and behaviour in horses in a vector-protected barn. Nine horses underwent two sequential stabling conditions: vector-protected barn housing and housing in a barn in which the air ventilation was explicitly adjusted. Heart rate was higher in the afternoon in horses housed in the barn without ventilation adjustment, whereas no change was observed in the barn with ventilation adjustment. The vector-protected housing increased the horses' behavioural scores. Blood cortisol level declined over time, and an earlier decrease was detected at 1400h in the barn with ventilation adjustment. Although airflow adjustment did not appear to statistically alter the stress response in horses during housing in the vector-protected barn, an earlier decline in cortisol level alongside an unchanged heart rate in horses during the day may indicate the positive impact of ventilation adjustment within the vector-protected barn. With limited options to reduce stress or discomfort in horses, this strategic protocol could, at least in part, be applied to managing horses' welfare during the AHS outbreak.

The Use of Confined Housing in Sand Bedding and Trimming to Manage Phalangeal Rotation and Hoof Malconformation Over a 20-Week Period in Two Laminitic Stallions.

Chronic laminitis is a late stage of laminitis in horses characterised by distal phalangeal rotation and foot pain. Various trimming and shoeing methods have been implemented; however, they sometimes aggravate lameness, particularly in laminitic horses with poor hoof quality. Sand bedding confinement has alternatively been employed to relieve foot pain in laminitic horses; however, the impact of long-term confined sand bed accommodation on hoof conditions is unknown. Moreover, the time course of sand bedding housing for managing chronic laminitis has yet to be described. We report the outcome of long-term housing in sand bedding confinement on hoof architectures and the time required for appropriate management of hoof malconformation. Two stallions, diagnosed with bilateral chronic laminitis and showing severe lameness following therapeutic shoeing, were assigned barefoot to confined sand bedding accommodations. Sole depth increased starting at 8 weeks; however, heel depth did not change throughout the housing period. A decrease in hoof angles was detected at 20 weeks of housing. An increase in sole depth/heel depth ratios was strongly correlated with the reduction in hoof angles. Therefore, long-term housing in sand bedding confinement for at least 20 weeks corrected phalangeal rotation and improved hoof conformation in two stallions with bilateral chronic laminitis. Further validation with a larger sample size is needed to determine whether this strategic housing management provides an alternative approach to treating hoof problems in laminitic horses that respond poorly to shoeing management.

Z-Bar Shoeing Demonstrates Potential for Long-Term Foot Pain Management during an Exercise Training Regimen in a Show Jumping Pony with Uniaxial Palmar Pain.

Z-bar shoeing has been implemented to relieve uniaxial palmar pain arising from the structures in the affected region. However, there have been no reports on the long-term application of the z-bar shoe during exercise training regimens. A 10-year-old mixed-breed show jumping pony presented with an occasional short stride and abnormal rhythm while turning during routine exercise for three months. Gait analysis conducted by trotting off on both hard and soft surfaces showed no lameness in the straight line on both types of surfaces. However, right forelimb lameness was detected with moderate and slight pain accompanying hard surface lunging in clockwise and counterclockwise directions, respectively. Sequential examination of uniaxial perineural anaesthesia confirmed that the pony suffered from medial palmar pain on the right foreleg. Mild distal border irregularity of the navicular bone was also observed radiographically. The z-bar shoe was designed relative to the palmar digital anaesthesia and subsequently applied on the lame leg. The pony demonstrated a marked reduction in lameness severity immediately post-Z-bar shoeing. Physical exercise was resumed a few days after the shoeing practice. The pony underwent routine exercise training while continuously fitting with the Z-bar shoe for 24 weeks without recurrent lameness or complications. Application of z-bar shoe showed the potential for long-term foot pain management during an exercise training regimen in a show jumping pony with uniaxial palmar pain.

Diagnostic imaging features, cytological examination, and treatment of lymphocytic tenosynovitis of the common digital extensor tendon sheath in an eventing horse.

In horses, the structures at the dorsal aspect of the carpus, including the digital extensor tendons, their related tendon sheaths, and bones, are vulnerable to injury because of their superficial location. Injuries to these structures may result in lameness of the affected limb(s) and reduce a horse's athletic performance. A 13-year-old eventing horse that routinely underwent regular exercise exhibited dorsolateral distension of the right carpus. An effusion insensitive to compression was observed in the affected area. No lameness was detected, and the horse exhibited a negative response to the carpal flexion test. Although radiography revealed no abnormal findings in the carpal bones, ultrasonography depicted anechoic fluid and synovial cell proliferation within the common digital extensor tendon sheath. Cytological analysis of the fluid revealed numerous lymphocytes and increased proteinaceous background, suggesting lymphocytic tenosynovitis. The effusion resolved following administration of two intrathecal injections: one injection of corticosteroid combined with hyaluronic acid (HA), and one injection of HA alone. Two weeks after administration of the second injection, daily under-saddle exercise was initiated, consisting of walking and light trotting with a gradual increase in intensity. The horse returned to its habitual intensive training program six weeks following the final injection. In conclusion, the horse was diagnosed with lymphocytic tenosynovitis of the common digital extensor tendon; successful treatment was achieved with administration of corticosteroid and HA. Diagnostic imaging and cytological examination facilitated clinical interpretation and the selection of an appropriate treatment regimen.

Modified Z-bar shoe eliminates occasional frog bruising accompanying Z-bar shoeing for navicular syndrome management in underrun-heeled horses.

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.

Diagnostic Imaging and Cytological Analysis Aid the Clinical Investigation of Long Digital Extensor Tendon Subtendinous Bursitis in a Horse.

The fetlock joint is a high mobility structure that accommodates enormous loading during locomotion. An injury of the superficial constituent such as subtendinous bursitis may occur due to repeated trauma. An 8-year old school riding horse was presented with dorsomedial distension in the left hindlimb fetlock region. The lesion was noted following routine exercise. The horse demonstrated no lameness and a negative response to the fetlock flexion test. Radiographic findings revealed a smooth surface cortical thickening on the medial aspect of the distal third metatarsal bone. Furthermore, the ultrasonography showed synovial thickening and proliferation, fibrous thickening with an irregular border in the inner synovial lining, and local protuberance of the fibrous layer within the bursa beneath the long digital extensor tendon. Cytological examination of the fluid from the distended lesion discovered multiple nucleated cells, including synoviocytes, nondegenerate neutrophils, lymphocytes, and macrophages. Eventually, the horse suffered subtendinous bursitis of long digital extensor tendon in the left hindlimb fetlock region. Intrabursa administration of 10 mg triamcinolone acetate alongside 25 mg hyaluronan (HA) and subsequent pressure bandaging were performed in the affected fetlock area. The distension was substantially reduced after the 4-week recovery period post medical administration. In summary, the horse was diagnosed with long digital extensor subtendinous bursitis that can occur accidentally. The diagnostic imaging and cytological analysis of accumulated fluid benefited a critical evaluation and facilitated the selection of the appropriate therapeutic plan for this defect.

A single bout of high-intensity exercise modulates the expression of vitamin D receptor and vitamin D-metabolising enzymes in horse skeletal muscle.

BACKGROUND: The expressions of vitamin D receptor (VDR) and vitamin D-metabolising enzymes (CYP27B1 and CYP24A1) in skeletal muscle have been reported. However, the regulation of this vitamin D system in horse skeletal muscle after high-intensity exercise has not yet been elucidated. OBJECTIVES: To investigate the effect of high-intensity exercise on the expression of vitamin D system-related proteins in horse skeletal muscle and its associations with skeletal muscle stem cell (SMSC) activity and serum 25(OH)D level. STUDY DESIGN: Longitudinal study. METHODS: Six healthy ponies (5 geldings, 1 mare; age 6.3 ± 2.2 years) were studied. Serum and muscle samples were taken from the jugular vein and gluteus medius respectively. Samples were collected at pre-exercise, post-exercise, 1 and 3 weeks after a single bout of high-intensity exercise. Protein expression levels of VDR, CYP27B1, CYP24A1, OxPhos and Pax7 (SMSC marker) were determined using immunohistochemical analysis. Oxidative capacity and intramuscular glycogen content were evaluated using histochemical analysis. Blood biochemistry was analysed for lactate concentration and creatine kinase (CK), and 25(OH)D activity. RESULTS: High-intensity exercise significantly upregulated Pax7 and VDR protein expression, which correlated with significantly increased blood lactate and serum CK levels immediately post-exercise. Serum 25(OH)D2 level correlated with CYP27B1 protein expression in skeletal muscle, and it reduced significantly immediately post-exercise and at 1 and 3 weeks post-exercise. However, CYP24A1 protein expression was unchanged throughout study periods. MAIN LIMITATION: The healthy ponies could not represent a fit population of racehorses and eventers. CONCLUSIONS: The rapid increase in Pax7 and VDR protein expression along with serum CK level after high-intensity exercise demonstrated an association between SMSC activity and activation of the vitamin D system in response to muscle injury in horses. Moreover, a decrease in CYP27B1 protein expression, correlated with a reduction in serum 25(OH)D2 , may indicate a compromised vitamin D metabolism after high-intensity exercise.

Chronic Atlantoaxial Luxation Imaging Features in a Pony with Intermittent Neck Stiffness.

A 17-year-old mixed breed pony was presented with intermittent neck stiffness during regular training rides in the six months preceding its admission. All parameters were within the normal range, except for an increase in heart rate (48 bpm) during the examination. Concave areas were observed at the level between the atlas and axis vertebrae (C1-C2) on both the left and right sides of the neck. Radiographs were taken of the laterolateral, left ventrodorsal oblique, and right ventrodorsal oblique projections in the cranial cervical region. The images revealed severe structural disorders, including trauma with luxation of the atlantoaxial joint, a fusion of the atlas and axis vertebrae, and evidence of a false joint in the axis bone. Subsequent ultrasonography showed hyperechoic areas in the rectus capitis caudalis and obliquus capitis caudalis muscles. Neck mobility was improved after two weeks of stall rest, administration of oral phenylbutazone (4.4 mg/kg), and topical cold gel treatment. The overstretching of surrounding soft tissues accompanying chronic injury of cranial cervical area may result in neck stiffness in the aging pony. Radiographic and ultrasonographic findings were consistent with the presence of cranial cervical trauma leading to neck stiffness. These findings emphasized the essential role of imaging diagnostics in treating a pony with intermittent neck stiffness.

Modulating effects of exercise training regimen on skeletal muscle properties in female polo ponies.

BACKGROUND: The match play patterns in equestrian polo are unique and require specific training programs to ensure sport performance. The effect of commonly used exercise training regimens on the adaptation of skeletal muscle is unclear. The present study investigated the modulating effects of the classic training regimen, comprised of aerobic exercise training with increasing exercise intensities and varying duration combined with match play, on the properties of muscle in polo ponies. Nine healthy adult female polo ponies were subjected to four consecutive subsets of 1 year classic training regimen including basal activity (B), low intensity (L), low to moderate intensity (LM), and low to moderate intensity training plus match play during polo tournament (LMP), respectively. At the end of each training period, gluteus medius muscle samples were taken for determination of muscle fiber type distribution, muscle metabolic capacity, capillary density, and lipid and glycogen content. The expression profile of metabolic genes including succinate dehydrogenase (SDH), phosphofructokinase (PFK), glycogen phosphorylase (PYG), and glycogen synthase (GYS) were also measured. RESULTS: Among all exercise training subsets, only LMP exercise period caused an increase in the number of oxidative fibers (type IIa), along with increases in properties related to oxidative metabolism including high capillary density, intramuscular lipid content, and expression of SDH and PYG genes, with a corresponding decrease in the number of type IIx muscle fibers. CONCLUSION: The combination of low to moderate and high intensity training in LMP are only sufficient to induce changes in oxidative characteristics. As the first scientific evidence providing such insight about the classic polo training regimen, the data forms a basis for further consideration in training program design.