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- Author or Editor: René van Weeren x
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Abstract
Objective—To determine effects of microcurrent electrical tissue stimulation (METS) on equine tenocytes cultured from the superficial digital flexor tendon (SDFT).
Sample Population—SDFTs were collected from 20 horses at slaughter.
Procedure—Tenocytes were isolated following outgrowth from explants and grown in 48-well plates. Four methods of delivering current to the tenocytes with a METS device were tested. Once the optimal method was selected, current consisting of 0 (negative control), 0.05, 0.1, 0.5, 1.0, or 1.5 mA was applied to cells (8 wells/current intensity) once daily for 8 minutes. Cells were treated for 1, 2, or 3 days. Cell proliferation, DNA content, protein content, and apoptosis rate were determined.
Results—Application of microcurrent of moderate intensity increased cell proliferation and DNA content, with greater increases with multiple versus single application. Application of microcurrent of moderate intensity once or twice increased protein content, but application 3 times decreased protein content. Application of current a single time did not significantly alter apoptosis rate; however, application twice or 3 times resulted in significant increases in apoptosis rate, and there were significant linear (second order) correlations between current intensity and apoptosis rate when current was applied twice or 3 times.
Conclusions and Clinical Relevance—Results of the present study indicate that microcurrent affects the behavior of equine tenocytes in culture, but that effects may be negative or positive depending on current intensity and number of applications. Therefore, results are far from conclusive with respect to the suitability of using METS to promote tendon healing in horses.
Abstract
Objective—To determine the relationship between the output of an electrical treatment device and the effective field strength in the superficial digital flexor tendon of horses.
Sample Population—Cadaver horse forelimbs without visible defects (n = 8) and 1 live pony.
Procedure—Microcurrents were generated by a microcurrent electrical therapy device and applied in proximodistal, dorsopalmar, and mediolateral directions in the entire forelimbs, dissected tendons, and the pony with various output settings. Corresponding field strengths in the tendons were measured.
Results—A linear relationship was detected between current and field strength in all conditions and in all 3 directions. In dissected tendons, significant differences were detected among all 3 directions, with highest field strength in the proximodistal direction and lowest in the dorsopalmar direction. In the entire forelimbs, field strength in the proximodistal direction was significantly lower than in the mediolateral direction. Results in the pony were similar to those in the entire forelimbs.
Conclusions and Clinical Relevance—Electrode placement significantly affected field strength in the target tissue. Many surrounding structures caused considerable reduction of field strength in the target tissue. These factors should be taken into account when establishing protocols for electrical current–based therapeutic devices if these devices are proven clinically effective.
Abstract
Objective—To determine movements of the vertebral column of horses during normal locomotion.
Animals—5 young Dutch Warmblood horses that did not have signs of back problems or lameness.
Procedure—Kinematics of 8 vertebrae (T6, T10, T13, T17, L1, L3, L5, and S3) and both tuber coxae were determined, using bone-fixated markers. Measurements were recorded when the horses were trotting on a treadmill at a constant speed of 4.0 m/s.
Results—Flexion-extension and axial rotation were characterized by a double sinusoidal pattern of motion during 1 stride cycle, whereas lateral bending was characterized by 1 peak and 1 trough. Ranges of motion for all vertebrae were: flexion-extension, 2.8o to 4.9o; lateral bending, 1.9° to 3.6°; axial rotation, 4.6° to 5.8°, except for T10 and T13, where the amount of axial rotation decreased to 3.1° and 3.3°, respectively.
Conclusion and Clinical Relevance—During locomotion, 3 types of rotations are evident in the thoracolumbar vertebrae. Regional differences are observed in the shape and timing of the rotations. These differences are related to actions of the limbs. The method described here for direct measurement of vertebral column motion provides insights into the complex movements of the thoracolumbar portion of the vertebral column in trotting horses. Information on normal kinematics is a prerequisite for a better understanding of abnormal function of the vertebral column in horses. (Am J Vet Res 2001;62:757–764)
Abstract
Objective—To determine whether serum concentrations of biomarkers of skeletal metabolism can, in conjunction with radiographic evaluation, indicate severity of osteochondrosis in developing horses.
Animals—43 Dutch Warmblood foals with varying severity of osteochondrosis.
Procedure—24 foals were monitored for 5 months and 19 foals were monitored for 11 months. Monthly radiographs of femoropatellar-femorotibial and tibiotarsal joints were graded for osteochondral abnormalities. Serial blood samples were assayed for 8 cartilage and bone biomarkers. At the end of the monitoring period, foals were examined for macroscopic osteochondrosis lesions.
Results—Temporal relationships were evident between certain serum biomarkers and osteochondrosis severity in foals during their first year. Biomarkers of collagen degradation (collagenasegenerated neoepitopes of type-II collagen fragments, type-I and -II collagen fragments [COL2-3/4Cshort], and cross-linked telopeptide fragments of type-I collagen) and bone mineralization (osteocalcin) were positive indicators of osteochondrosis severity at 5 months of age. In foals with lesions at 11 months of age, osteochondrosis severity correlated negatively with COL2-3/4Cshort and osteocalcin and positively with C-propeptide of type-II procollagen (CPII), a collagen synthesis marker. Radiographic grading of osteochondrosis lesions significantly correlated with macroscopic osteochondrosis severity score at both ages and was strongest when combined with osteocalcin at 5 months and CPII at 11 months.
Conclusions and Clinical Relevance—The ability of serum biomarkers to indicate osteochondrosis severity appears to depend on stage of disease and is strengthened with radiography. In older foals with more permanent lesions, osteochondrosis severity is significantly related to biomarker concentrations of decreased bone formation and increased cartilage synthesis. (Am J Vet Res 2004;65:143–150)
Abstract
Objective—To investigate the effects of moderate short-term training on K+ regulation in plasma and erythrocytes during exercise and on skeletal muscle Na+,K+-ATPase concentration in young adult and middle-aged horses.
Animals—Four 4- to 6-year-old and four 10- to 16-yearold Dutch Warmblood horses.
Procedure—The horses underwent a 6-minute exercise trial before and after 12 days of training. Skeletal muscle Na+,K+-ATPase concentration was analyzed in gluteus medius and semitendinosus muscle specimens before and after the 12-day training period. Blood samples were collected before and immediately after the trials and at 3, 5, 7, and 10 minutes after cessation of exercise for assessment of several hematologic variables and analysis of plasma and whole-blood K+ concentrations.
Results—After training, Na+,K+-ATPase concentration in the gluteus medius, but not semitendinosus, muscle of middle-aged horses increased (32%), compared with pretraining values; this did not affect the degree of hyperkalemia that developed during exercise. The development of hyperkalemia during exercise in young adult horses was blunted (albeit not significantly) without any change in the concentration of Na+,K+-ATPase in either of the muscles. After training, the erythrocyte K+ concentration increased (7% to 10%) significantly in both groups of horses but did not change during the exercise trials.
Conclusions and Clinical Relevance—In horses, the activation of skeletal muscle Na+,K+-ATPase during exercise is likely to decrease with age. Training appears to result in an increase in Na+,K+-ATPase activity in skeletal muscle with subsequent upregulation of Na+,K+-ATPase concentration if the existing Na+,K+-ATPase capacity cannot meet requirements. (Am J Vet Res 2005;66:1252–1258)
Abstract
Objective—To determine kinematic movements of the vertebral column of horses during normal locomotion.
Animals—5 Dutch Warmblood horses without apparent lameness or problems associated with the vertebral column.
Procedure—Kinematics of 8 vertebrae (T6, T10, T13, T17, L1, L3, L5, and S3) and both tuber coxae were determined, using bone-fixated markers. Horses were recorded while walking on a treadmill at a constant speed of 1.6 m/s.
Results—Flexion-extension was characterized by 2 periods of extension and flexion during 1 stride cycle, whereas lateral bending and axial rotation were characterized by 1 peak and 1 trough. The range of motion for flexion-extension was fairly constant for vertebrae caudal to T10 (approximately 7°). For lateral bending, the cranial thoracic vertebrae and segments in the pelvic region had the maximal amount of motion, with values of up to 5.6°. For vertebrae between T17 and L5, the amount of lateral bending decreased to < 4°. The amount of axial rotation increased gradually from 4° for T6 to 13° for the tuber coxae.
Conclusions—This direct measurement method provides 3-dimensional kinematic data for flexion-extension, lateral bending, and axial rotation of the thoracolumbar portion of the vertebral column of horses walking on a treadmill. Regional differences were observed in the magnitude and pattern of the rotations. Understanding of the normal kinematics of the vertebral column in healthy horses is a prerequisite for a better understanding of abnormal function. (Am J Vet Res 2000;61:399–406)
Abstract
Objective—To quantify and compare biochemical characteristics of the extracellular matrix (ECM) of specimens harvested from tensional and compressive regions of the superficial digital flexor tendon (SDFT) of horses in age classes that include neonates to mature horses.
Sample Population—Tendon specimens were collected on postmortem examination from 40 juvenile horses (0, 5, 12, and 36 months old) without macroscopically visible signs of tendonitis.
Procedure—Central core specimens of the SDFT were obtained with a 4-mm-diameter biopsy punch from 2 loaded sites, the central part of the midmetacarpal region and the central part of the midsesamoid region. Biochemical characteristics of the collagenous ECM content (ie, collagen, hydroxylysylpyridinoline crosslink, and pentosidine crosslink concentrations and percentage of degraded collagen) and noncollagenous ECM content (percentage of water and glycosaminoglycans, DNA, and hyaluronic acid concentrations) were measured.
Results—The biochemical composition of equine SDFT was not homogeneous at birth with respect to DNA, glycosaminoglycans, and pentosidine concentrations. For most biochemical variables, the amounts present at birth were dissimilar to those found in mature horses. Fast and substantial changes in all components of the matrix occurred in the period of growth and development after birth.
Conclusions and Clinical Relevance—Unlike cartilage, tendon tissue is not biochemically blank (ie, homogeneous) at birth. However, a process of functional adaptation occurs during maturation that changes the composition of equine SDFT from birth to maturity. Understanding of the maturation process of the juvenile equine SDFT may be useful in developing exercise programs that minimize tendon injuries later in life that result from overuse. (Am J Vet Res 2005;66:1623–1629)
Abstract
Objective—To evaluate quantitative ultrasonography for objective monitoring of the healing process and prognostication of repair quality in equine superficial digital flexor (SDF) tendons.
Animals—6 horses with standardized surgical lesions in SDF tendons of both forelimbs.
Procedures—Healing was monitored for 20 weeks after surgery by use of computerized ultrasonography. Pixels were categorized as C (intact fasciculi), B (incomplete fasciculi), E (accumulations of cells and fibrils), or N (homogenous fluid or cells). Four scars with the best quality of repair (repair group) and 4 scars with the lowest quality (inferior repair group) were identified histologically. Ratios for C, B, E, and N in both groups were compared.
Results—During 4 weeks after surgery, lesions increased 2- to 4-fold in length and 10-fold in volume. Until week 3 or 4, structure-related C and B ratios decreased sharply, whereas E and N ratios increased. After week 4, C and B ratios increased with gradually decreasing E and N ratios. At week 12, C and B ratios were equivalent. After week 12, C ratio increased slowly, but B ratio more rapidly. At week 20, C ratio remained constant, B ratio was substantially increased, and E and N ratios decreased. Values for the inferior repair group were most aberrant from normal. Ratios for C differed significantly between repair and inferior repair groups at weeks 16 and 18 and for B beginning at 14 weeks.
Conclusions and Clinical Relevance—Computerized ultrasonography provided an excellent tool for objective monitoring of healing tendons in horses and reliable prognostication of repair quality.
Abstract
Objective—To investigate the effects of early training for jumping by comparing the jumping technique of horses that had received early training with that of horses raised conventionally.
Animals—40 Dutch Warmblood horses.
Procedure—The horses were analyzed kinematically during free jumping at 6 months of age. Subsequently, they were allocated into a control group that was raised conventionally and an experimental group that received 30 months of early training starting at 6 months of age. At 4 years of age, after a period of rest in pasture and a short period of training with a rider, both groups were analyzed kinematically during free jumping. Subsequently, both groups started a 1-year intensive training for jumping, and at 5 years of age, they were again analyzed kinematically during free jumping. In addition, the horses competed in a puissance competition to test maximal performance.
Results—Whereas there were no differences in jumping technique between experimental and control horses at 6 months of age, at 4 years, the experimental horses jumped in a more effective manner than the control horses; they raised their center of gravity less yet cleared more fences successfully than the control horses. However, at 5 years of age, these differences were not detected. Furthermore, the experimental horses did not perform better than the control horses in the puissance competition.
Conclusions and Clinical Relevance—Specific training for jumping of horses at an early age is unnecessary because the effects on jumping technique and jumping capacity are not permanent. (Am J Vet Res 2005;66:418–424)
Abstract
Objective—To quantify variation in the jumping technique within and among young horses with little jumping experience, establish relationships between kinetic and kinematic variables, and identify a limited set of variables characteristic for detecting differences in jumping performance among horses.
Animals—Fifteen 4-year-old Dutch Warmblood horses.
Procedure—The horses were raised under standardized conditions and trained in accordance with a fixed protocol for a short period. Subsequently, horses were analyzed kinematically during free jumping over a fence with a height of 1.05 m.
Results—Within-horse variation in all variables that quantified jumping technique was smaller than variation among horses. However, some horses had less variation than others. Height of the center of gravity (CG) at the apex of the jump ranged from 1.80 to 2.01 m among horses; this variation could be explained by the variation in vertical velocity of the CG at takeoff ( r, 0.78). Horses that had higher vertical velocity at takeoff left the ground and landed again farther from the fence, had shorter push-off phases for the forelimbs and hind limbs, and generated greater vertical acceleration of the CG primarily during the hind limb pushoff. However, all horses cleared the fence successfully, independent of jumping technique.
Conclusions and Clinical Relevance—Each horse had its own jumping technique. Differences among techniques were characterized by variations in the vertical velocity of the CG at takeoff. It must be determined whether jumping performance later in life can be predicted from observing free jumps of young horses. ( Am J Vet Res 2004;65:938–944)
