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  • Author or Editor: C. Wayne McIlwraith x
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Abstract

Objective—To assess the clinical, biochemical, and histologic effects of topically administered diclofenac liposomal cream (DLC) in the treatment of horses with experimentally induced osteoarthritis.

Animals—24 horses.

Procedures—Osteoarthritis was induced arthroscopically in 1 middle carpal joint of all horses. Eight horses treated with DLC were given 7.3 g twice daily via topical application. Eight horses treated with phenylbutazone were given 2 g orally once daily. Eight control horses received no treatment. Evaluations included clinical, radiographic, magnetic reso-nance imaging, synovial fluid, gross, and histologic examinations as well as histochemical and biochemical analyses.

Results—No adverse treatment-related events were detected. Horses that were treated with DLC or phenylbutazone had significant clinical improvement of lameness, unlike the control horses. Treatment with DLC induced significant improvement in staining and total articular glycosaminoglycan content, compared with no treatment. Treatment with phen-ylbutazone induced significant reduction in synovial fluid prostaglandin E2 concentration, compared with DLC and no treatment. Treatment with DLC induced significantly less radial carpal bone sclerosis and overall gross cartilage erosion, compared with phenylbutazone.

Conclusions and Clinical Relevance—Results indicated that DLC had both clinical sign–modifying and disease-modifying effects. Only clinical sign–modifying effects were detected in association with phenylbutazone administration. Treatment with DLC had significant beneficial effects, compared with phenylbutazone, and no detrimental effects. Results suggested that DLC is a viable therapeutic option for horses with osteoarthritis.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To assess the clinical, biochemical, and histologic effects of intra-articular administration of autologous conditioned serum (ACS) in the treatment of experimentally induced osteoarthritis in horses.

Animals—16 horses.

Procedures—Osteoarthritis was induced arthroscopically in 1 middle carpal joint of all horses. In 8 placebo- and 8 ACS-treated horses, 6 mL of PBS solution or 6 mL of ACS was injected into the osteoarthritis-affected joint on days 14, 21, 28, and 35, respectively; PBS solution was administered in the other sham-operated joints. Evaluations included clinical assessment of lameness and synovial fluid analysis (performed biweekly); gross pathologic and histologic examinations of cartilage and synovial membrane samples were performed at necropsy.

Results—No adverse treatment-related events were detected. Horses that were treated with ACS had significant clinical improvement in lameness, unlike the placebo-treated horses. Among the osteoarthritis-affected joints, ACS treatment significantly decreased synovial membrane hyperplasia, compared with placebo-treated joints; although not significant, the ACS-treated joints also appeared to have less gross cartilage fibrillation and synovial membrane hemorrhage. The synovial fluid concentration of interleukin-1 receptor antagonist (assessed by use of mouse anti–interleukin-1 receptor antagonist antibody) was increased following treatment with ACS.

Conclusions and Clinical Relevance—Results of this controlled study indicated that there was significant clinical and histologic improvement in osteoarthritis-affected joints of horses following treatment with ACS, compared with placebo treatment. On the basis of these findings, further controlled clinical trials to assess this treatment are warranted, and investigation of the mechanisms of action of ACS should be pursued concurrently.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether muscle moment arms at the carpal and metacarpophalangeal joints can be modeled as fixed-radius pulleys for the range of motion associated with the stance phase of the gait in equine forelimbs.

Sample Population—4 cadaveric forelimbs from 2 healthy Thoroughbreds.

Procedure—Thin wire cables were sutured at the musculotendinous junction of 9 forelimb muscles. The cables passed through eyelets at each muscle's origin, wrapped around single-turn potentiometers, and were loaded. Tendon excursions, measured as the changes in lengths of the cables, were recorded during manual rotation of the carpal (180° to 70°) and metacarpophalangeal (220° to 110°) joints. Extension of the metacarpophalangeal joint (180° and 220°) was forced with an independent loading frame. Joint angle was monitored with a calibrated potentiometer. Moment arms were calculated from the slopes of the muscle length versus joint angle curves.

Results—At the metacarpophalangeal joint, digital flexor muscle moment arms changed in magnitude by ≤ 38% during metacarpophalangeal joint extension. Extensor muscle moment arms at the carpal and metacarpophalangeal joints also varied (≤ 41% at the carpus) over the range of joint motion associated with the stance phase of the gait.

Conclusions and Clinical Relevance—Our findings suggest that, apart from the carpal flexor muscles, muscle moment arms in equine forelimbs cannot be modeled as fixed-radius pulleys. Assuming that muscle moment arms at the carpal and metacarpophalangeal joints have constant magnitudes may lead to erroneous estimates of muscle forces in equine forelimbs. (Am J Vet Res 2003;64:351–357)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To develop an in vitro model of cartilage injury in full-thickness equine cartilage specimens that can be used to simulate in vivo disease and evaluate treatment efficacy.

Sample—15 full-thickness cartilage explants from the trochlear ridges of the distal aspect of the femur from each of 6 adult horses that had died from reasons unrelated to the musculoskeletal system.

Procedures—To simulate injury, cartilage explants were subjected to single-impact uniaxial compression to 50%, 60%, 70%, or 80% strain at a rate of 100% strain/s. Other explants were left uninjured (control specimens). All specimens underwent a culture process for 28 days and were subsequently evaluated histologically for characteristics of injury and early stages of osteoarthritis, including articular surface damage, chondrocyte cell death, focal cell loss, chondrocyte cluster formation, and loss of the extracellular matrix molecules aggrecan and types I and II collagen.

Results—Compression to all degrees of strain induced some amount of pathological change typical of clinical osteoarthritis in horses; however, only compression to 60% strain induced significant changes morphologically and biochemically in the extracellular matrix.

Conclusions and Clinical Relevance—The threshold strain necessary to model injury in full-thickness cartilage specimens from the trochlear ridges of the distal femur of adult horses was 60% strain at a rate of 100% strain/s. This in vitro model should facilitate study of pathophysiologic changes and therapeutic interventions for osteoarthritis.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the effect of underwater treadmill exercise on static postural sway in horses with experimentally induced carpal joint osteoarthritis under various stance conditions.

Animals—16 horses.

Procedures—On day 0, osteoarthritis was induced arthroscopically in 1 randomly selected middle carpal joint of each horse. Beginning on day 15, horses were assigned to either underwater or overground (without water) treadmill exercise at the same speed, frequency, and duration. Two serial force platforms were used to collect postural sway data from each horse on study days −7, 14, 42, and 70. Horses were made to stand stationary on the force platforms under 3 stance conditions: normal square stance, base-narrow placement of the thoracic limbs, and removal of visual cues (blindfolded) during a normal square stance. The mean of 3 consecutive, 10-second trials in each condition was calculated and used for analysis.

Results—Displacement of the center of pressure differed significantly depending on the stance condition. Among horses exercised on the underwater treadmill, postural stability in both the base-narrow and blindfolded stance conditions improved, compared with findings for horses exercised on the overground treadmill. Horses exercised on the overground treadmill were only successful at maintaining a stable center of pressure during the normal square stance position.

Conclusions and Clinical Relevance—Variations in stance position had profound effects on the mechanics of standing balance in horses with experimentally induced carpal joint osteoarthritis. Underwater treadmill exercise significantly improved the horses’ postural stability, which is fundamental in providing evidence-based support for equine aquatic exercise.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine kinematic changes to the hoof of horses at a trot after induction of unilateral, weight-bearing forelimb lameness and to determine whether hoof kinematics return to prelameness values after perineural anesthesia.

Animals—6 clinically normal Quarter Horses.

Procedures—For each horse, a sole-pressure model was used to induce 3 grades (grades 1, 2, and 3) of lameness in the right forelimb, after which perineural anesthesia was administered to alleviate lameness. Optical kinematics were obtained for both forelimbs with the horse trotting before (baseline) and after induction of each grade of lameness and after perineural anesthesia. Hoof events were identified with linear acceleration profiles, and each stride was divided into hoof-contact, break-over, initial-swing, terminal-swing, and total-swing segments. For each segment, kinematic variables were compared within and between limbs by use of mixed repeated-measures ANOVA.

Results—During hoof-contact, the left (nonlame) forelimb hoof had greater heel-down orientation than did the right (lame) forelimb hoof, and during break-over, the nonlame hoof went through a larger range of motion than did the lame hoof. Maximum cranial acceleration during break-over for the lame hoof was greater, compared with that at baseline or for the nonlame hoof. Following perineural anesthesia, the sagittal plane orientation of the hoof during hoof-contact did not vary between the lame and nonlame limbs; however, interlimb differences in maximum cranial acceleration and angular range of motion during break-over remained.

Conclusions and Clinical Relevance—Results suggested that hoof kinematics may be useful for detection of unilateral, weight-bearing forelimb lameness in horses that are trotting.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine kinematic changes to the hoof of horses at a walk after induction of unilateral, weight-bearing forelimb lameness and to determine whether hoof kinematics return to prelameness (baseline) values after perineural anesthesia.

Animals—6 clinically normal Quarter Horses.

Procedures—For each horse, a sole-pressure model was used to induce 3 grades of lameness in the right forelimb, after which perineural anesthesia was administered to eliminate lameness. Optical kinematics were obtained for both forelimbs with the horse walking before (baseline) and after induction of each grade of lameness and after perineural anesthesia. Linear acceleration profiles were used to identify hoof events, and each stride was divided into hoof-contact, break-over, initial-swing, terminal-swing, and total-swing segments. Kinematic variables were compared within and between limbs for each segment by use of mixed repeated-measures ANOVA.

Results—During the hoof-contact and terminal-swing segments, the hoof of the left (nonlame) forelimb had greater sagittal-plane orientation than did the hoof of the right (lame) forelimb. For the lame limb following lameness induction, the break-over duration and maximum cranial acceleration were increased from baseline. After perineural anesthesia, break-over duration for the lame limb returned to a value similar to that at baseline, and orientation of the hoof during the terminal-swing segment did not differ between the lame and nonlame limbs.

Conclusions and Clinical Relevance—Subclinical unilateral forelimb lameness resulted in significant alterations to hoof kinematics in horses that are walking, and the use of hoof kinematics may be beneficial for the detection of subclinical lameness in horses.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To determine the effects of altering location of right forelimb and pelvic sensors on kinematic data obtained with a commonly used inertial sensor system during gait analysis of trotting horses.

DESIGN Experimental study.

ANIMALS 12 horses with mild to moderate lameness of at least 1 hind limb, with or without lameness of the forelimbs.

PROCEDURES All horses were examined while trotting on a high-speed treadmill. The right forelimb sensor was tested at 3 anatomic locations in random order: dorsal midline and 2 cm medial and lateral to that midline. During another treadmill session, the pelvic sensor was tested at 5 anatomic locations in random order: dorsal midline, 2 cm to the right and left of midline, and 2 cm cranial and caudal to the tubera sacrale on the midline. Laterality of the pelvic sensor was analyzed in 2 ways: sensor toward the right or left and sensor toward or away from the lame or lamest hind limb. Maximum and minimum differences in head and pelvic motion and vector sum values were ranked and compared with values for the midline location by means of mixed-model ANOVA.

RESULTS Altering the location of the right forelimb sensor by 2 cm medially or laterally had no significant effect on forelimb or hind limb kinematics. However, location of the pelvic sensor had a significant effect on minimum difference in pelvic motion, regardless of whether the data were analyzed by laterality (right vs left) or toward versus away from the lame hind limb.

CONCLUSIONS AND CLINICAL RELEVANCE Results of this study indicated that a 2-cm change in the location of the pelvic sensor during kinematic gait analysis had a significant effect on hind limb kinematic data of the system used. Therefore, placement of this sensor needs to be anatomically accurate.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To validate an equine inertial measurement unit (IMU) system rigidly attached to a hoof against a 3-D optical kinematics system in horses during walking and trotting.

Animals—5 clinically normal horses.

Procedures—5 swing phases of the hooves of the right forelimb and hind limb were collected via both 3-D optical and IMU systems from 5 horses during walking and trotting. Linear and angular positions, velocities, and accelerations were compared between the 2 systems.

Results—Of the 55 variables compared between the 2 systems, 25 had high correlations (r > 0.8) and 18 had moderate correlations (r > 0.5). Root mean squared errors were lowest in the sagittal plane and orientation (1.1 to 4.4 cm over a range of 1.5 to 1.9 m in the cranial-caudal direction and 2.5° to 3.5° over a range of 88° to 110° rotating around the medial-lateral axis). There were more differences between the 2 systems during small changes in motion, such as in the medial-lateral and proximal-distal directions and in the angular measures around the cranial-caudal and proximal-distal axes.

Conclusions and Clinical Relevance—The equine IMU system may be appropriate for rigid attachment to a hoof of a horse and use in examination of linear and angular motion in the sagittal plane of the hoof during the swing phase while walking and trotting. Although promising in many respects, the IMU system cannot currently be considered clinically useful for lameness evaluation because of limitations in accuracy, attachment method, and lack of stance phase evaluation.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To investigate effects of 1% hyaluronic acid–chondroitin sulfate–N-acetyl glucosamine (HCNAG) on the damage repair response in equine articular cartilage.

Sample—Articular cartilage from 9 clinically normal adult horses.

Procedures—Full-thickness cartilage disks were harvested from the third metacarpal bone. Cartilage was single-impact loaded (SIL) with 0.175 J at 0.7 m/s and cultured in DMEM plus 1 % (vol/vol) HCNAG or fibroblastic growth factor (FGF)-2 (50 ng/mL). Histologic and immunohistochemical techniques were used to identify tissue architecture and apoptotic cells and to immunolocalize type I and II collagen and proliferating nuclear cell antigen (PCNA).

Results—Type II collagen immunoreactivity increased in SIL cartilage, compared with control samples. At days 14 and 28 (day 0 = initiation of culture), control samples had significantly fewer repair cells than did other treatment groups. In control samples and SIL + HCNAG, there was a significant decrease in apoptotic cell number, compared with results for SIL and SIL + FGF-2 samples. At days 14 and 28, there was a significant increase in chondrocytes stained positive for PCNA in the control samples.

Conclusions and Clinical Relevance—1% HCNAG significantly affected apoptotic and repair cell numbers in an SIL damage-repair technique in adult equine articular cartilage. However, HCNAG had no effect on the number of PCNA-positive chondrocytes or on type II collagen immunohistochemical results. The inclusion of 1% HCNAG in lavage solutions administered after arthroscopy may be beneficial to cartilage health by increasing the number of repair cells and decreasing the number of apoptotic cells.

Full access
in American Journal of Veterinary Research