OBJECTIVE To evaluate the analgesic and tissue effects of liposomal bupivacaine administered SC as an abaxial sesamoid nerve block in horses with experimentally induced lameness. ANIMALS 6 healthy mature light-breed horses. PROCEDURES In a randomized crossover study, a circumferential hoof clamp was applied to a forelimb to induce reversible lameness. An abaxial sesamoid nerve block of the lame forelimb was performed by SC perineural injection of 10 mg of liposomal bupivacaine or bupivacaine HCl/site. Quantitative gait data were objectively obtained with a body-mounted inertial sensor system before (baseline) and at 30-minute intervals after treatment. Time to return to 85% of baseline lameness was determined. After a minimum 4-day washout period, procedures were repeated with the alternate limb and treatment. Lastly, the palmar digital nerves and perineural tissues were collected and examined histologically. RESULTS SC perineural injection of liposomal bupivacaine ameliorated forelimb lameness in 5 of 6 horses. The median duration of analgesia was not significantly different between liposomal bupivacaine (4.5 hours) and bupivacaine HCl (3.0 hours). Histologically, mild inflammation was noted in 3 of 10 sites injected with liposomal bupivacaine and in none of the sites injected with bupivacaine HCl. CONCLUSIONS AND CLINICAL RELEVANCE SC perineural injection of 10 mg of liposomal bupivacaine/site ameliorated experimentally induced forelimb lameness in some horses. At milligram-equivalent doses, liposomal bupivacaine had a similar duration of analgesia to that of bupivacaine HCl. Further investigation is required before recommending clinical use of liposomal bupivacaine for nerve blocks in horses.

OBJECTIVE To use the small data approach of the Clinical and Laboratory Standards Institute (CLSI) to evaluate the transferability of reference intervals (RIs) for kinetic variables obtained with instrumented gait analysis (IGA) in dogs from an RI-originator laboratory to another laboratory that used the same data acquisition and analytic techniques for IGA in walking dogs. ANIMALS 27 adult client-owned dogs without evidence of lameness. PROCEDURES Dogs were individually walked at their preferred velocity on a pressure-sensing walkway for IGA at the Colorado State University Animal Gait Laboratory (CSU-AGL), and 6 valid trials were analyzed for each dog. The small data approach of the CLSI was then used to evaluate transferability of RIs previously established at the Purdue University Animal Gait Laboratory (PU-AGL). A linear model was used to establish weight-dependent RIs for peak vertical force (PVF). RESULTS Results indicated that RIs of dynamic weight distribution (DWD), DWD symmetry index, DWD coefficient of variation, PVF symmetry index, and PVF coefficient of variation were transferable from PU-AGL to CSU-AGL, whereas the weight-dependent RIs for PVF were not. Regression slopes for PVF versus body weight were greater for all limbs in dogs tested at the CSU-AGL, compared with historic results for dogs tested at the PU-AGL. CONCLUSIONS AND CLINICAL RELEVANCE Use of the small data approach method of the CLSI to validate transference of RIs for IGA kinetic variables in walking dogs was simple and efficient to perform and may help facilitate clinical and research collaborations on gait analysis.

OBJECTIVE To compare the speed of onset and analgesic effect of mepivacaine deposited within or immediately outside the neurovascular bundle at the base of the proximal sesamoid bones in horses. ANIMALS 6 horses with naturally occurring forefoot-related lameness. PROCEDURES In a crossover study design, horses were randomly assigned to receive 1 of 2 treatments first, with the second treatment administered 3 to 7 days later. Trotting gait was analyzed with an inertial sensor–based motion analysis system immediately before treatment to determine degree of lameness. Afterward, ultrasound guidance was used to inject 2% mepivacaine hydrochloride around the palmar digital nerves of the affected forelimb at the level of the base of the proximal sesamoid bones either within the subcircumneural space or outside the circumneural sheath. After injection, gait was reevaluated at 5-minute intervals for 45 minutes. RESULTS Mepivacaine deposition outside the circumneural sheath did not resolve lameness in any horse; for 3 horses, the mean time to 70% reduction of initial vertical head movement was 13.3 minutes, and the remaining 3 horses had no such reduction at any point. Mepivacaine deposition within the subcircumneural space resulted in a mean time to 70% reduction of initial vertical head movement of 6.7 minutes and mean time to resolution of lameness of 21.7 minutes. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that when peripheral nerves of horses lie within a sheath, local anesthetic solution should be deposited within the sheath for an effective nerve block. If local anesthetic solution is deposited outside the sheath, the nerve block may yield erroneous results.

OBJECTIVE To assess effects of speed on kinematic variables measured by use of extremity-mounted inertial measurement units (IMUs) in nonlame horses performing controlled exercise on a treadmill. ANIMALS 10 nonlame horses. PROCEDURES 6 IMUs were attached at predetermined locations on 10 nonlame Franches Montagnes horses. Data were collected in triplicate during trotting at 3.33 and 3.88 m/s on a high-speed treadmill. Thirty-three selected kinematic variables were analyzed. Repeated-measures ANOVA was used to assess the effect of speed. RESULTS Significant differences between the 2 speeds were detected for most temporal (11/14) and spatial (12/19) variables. The observed spatial and temporal changes would translate into a gait for the higher speed characterized by increased stride length, protraction and retraction, flexion and extension, mediolateral movement of the tibia, and symmetry, but with similar temporal variables and a reduction in stride duration. However, even though the tibia coronal range of motion was significantly different between speeds, the high degree of variability raised concerns about whether these changes were clinically relevant. For some variables, the lower trotting speed apparently was associated with more variability than was the higher trotting speed. CONCLUSIONS AND CLINICAL RELEVANCE At a higher trotting speed, horses moved in the same manner (eg, the temporal events investigated occurred at the same relative time within the stride). However, from a spatial perspective, horses moved with greater action of the segments evaluated. The detected changes in kinematic variables indicated that trotting speed should be controlled or kept constant during gait evaluation.

OBJECTIVE To characterize clinical findings for polysaccharide storage myopathy (PSSM) in warmblood horses with type 1 PSSM (PSSM1; caused by mutation of the glycogen synthase 1 gene) and type 2 PSSM (PSSM2; unknown etiology). SAMPLE Database with 3,615 clinical muscle biopsy submissions. PROCEDURES Reported clinical signs and serum creatine kinase (CK) and aspartate aminotransferase (AST) activities were retrospectively analyzed for horses with PSSM1 (16 warmblood and 430 nonwarmblood), horses with PSSM2 (188 warmblood and 646 nonwarmblood), and warmblood horses without PSSM (278). Lameness examinations were reviewed for 9 warmblood horses with PSSM2. Muscle glycogen concentrations were evaluated for horses with PSSM1 (14 warmblood and 6 nonwarmblood), warmblood horses with PSSM2 (13), and horses without PSSM (10 warmblood and 6 nonwarmblood). RESULTS Rhabdomyolysis was more common for horses with PSSM1 (12/16 [75%] warmblood and 223/303 [74%] nonwarmblood) and nonwarmblood horses with PSSM2 (221/436 [51%]) than for warmblood horses with PSSM2 (39/147 [27%]). Gait abnormality was more common in warmblood horses with PSSM2 (97/147 [66%]) than in warmblood horses with PSSM1 (1/16 [7%]), nonwarmblood horses with PSSM2 (176/436 [40%]), and warmblood horses without PSSM (106/200 [53%]). Activities of CK and AST were similar in warmblood horses with and without PSSM2. Muscle glycogen concentrations in warmblood and nonwarmblood horses with PSSM1 were significantly higher than concentrations in warmblood horses with PSSM2. CONCLUSIONS AND CLINICIAL RELEVANCE Rhabdomyolysis and elevated muscle glycogen concentration were detected in horses with PSSM1 regardless of breed. Most warmblood horses with PSSM2 had stiffness and gait abnormalities with CK and AST activities and muscle glycogen concentrations within reference limits.

OBJECTIVE To characterize a population of Brazilian minipigs with naturally occurring syndactyly by use of plain radiographs and CT images and to evaluate kinetic and temporospatial variables by use of a pressure-sensing walkway. ANIMALS 10 Brazilian minipigs from 6 to 8 months of age (group 1, 5 healthy pigs [body weight, 10.5 to 18.5 kg]; group 2, 5 pigs with syndactyly [body weight, 7.5 to 18.0 kg]). PROCEDURES Forelimbs and hind limbs of all pigs were assessed by use of radiography and CT. Gait was analyzed by use of a pressure-sensing walkway. RESULTS All limbs of all pigs of group 2 had syndactyly. Two forelimbs had complex-1 syndactyly, and 8 forelimbs had complex-2 syndactyly. Four hind limbs had simple syndactyly, 1 hind limb had complex-1 syndactyly, and 5 hind limbs had complex-2 syndactyly. Kinetic and temporospatial values and symmetry indices did not differ between groups. Plantar and palmar surfaces of healthy pigs had 2 areas of maximum pressure, whereas plantar and palmar surfaces of pigs with syndactyly had only 1 area of maximum pressure. CONCLUSIONS AND CLINICAL RELEVANCE In this population of pigs, the most common type of syndactyly was complex-2, and comparison with the healthy group revealed no alteration in kinetic and temporospatial variables. Therefore, results suggested that syndactyly in young minipigs did not cause locomotor disturbances.

OBJECTIVE To compare gait mechanics and limb loading in Icelandic horses tölting and trotting at equal speeds and estimate their impact on orthopedic health. ANIMALS 12 orthopedically normal Icelandic horses. PROCEDURES Kinetic and kinematic gait variables were simultaneously recorded as each horse was ridden at a tölt and trot on an instrumented treadmill at 3.4 m/s and 3.9 m/s. Differences between gaits were tested via 1-factor repeated-measures ANOVA. RESULTS Horses had a higher stride rate and lower stride impulses at a tölt than at a trot. For forelimbs at a tölt, shorter relative stance duration resulted in higher peak vertical force (Fz(peak)). Conversely, for hind limbs, longer relative stance duration resulted in lower Fz(peak). The higher head-neck position at a tölt versus trot caused no weight shift to the hind limbs, but a higher forehoof flight arc and lower proretraction movement were identified. Stance durations for forelimbs were briefer than for hind limbs at a tölt, and the inverse was observed at a trot. Minimal height of the horse's trunk at the point of Fz(peak) of the respective limb suggested a spring-like mechanism for all limbs at a tölt. Hind limb measurements revealed no evidence of increased collection. Stride-to-stride limb timing varied more at a tölt than at a trot. At a trot, horses had brief or no suspension phases and a slightly 4-beated footfall rhythm was common. Post hoc energetic estimations revealed that tölting at the measured speeds was less advantageous than trotting. CONCLUSIONS AND CLINICAL RELEVANCE High forelimb action in Icelandic horses and higher head-neck position at a tölt were associated with more restricted limb proretraction, higher Fzpeak, and faster force onset than at a trot. The impact of these differences on orthopedic health needs to be investigated more in detail.

Objective - To compare accuracy of a noninvasive single-plane fluoroscopic technique with radiostereometric analysis (RSA) for determining 3-D femorotibial poses in a canine cadaver with normal stifle joints. Sample- Right pelvic limb from a 25-kg adult mixed-breed dog. Procedures- A CT scan of the limb was obtained before and after metal beads were implanted into the right femur and tibia. Orthogonal fluoroscopic images of the right stifle joint were acquired to simulate a biplanar fluoroscopic acquisition setup. Images were obtained at 5 flexion angles from 110° to 150° to simulate a gait cycle; 5 cycles were completed. Joint poses were calculated from the biplanar images by use of RSA with CT-derived beaded bone models and compared with measurements obtained by use of CT-derived nonbeaded bone models matched to single-plane, lateral-view fluoroscopic images. Single-plane measurements were performed by 2 observers and repeated 3 times by the primary observer. Results- Mean absolute differences between the single-plane fluoroscopic analysis and RSA measurements were 0.60, 1.28, and 0.64 mm for craniocaudal, proximodistal, and mediolateral translations, respectively, and 0.63°, 1.49°, and 1.58° for flexion-extension, abduction-adduction, and internal-external rotations, respectively. Intra- and interobserver repeatability was strong with maximum mean translational and rotational SDs of 0.52 mm and 1.36°, respectively. Conclusions and Clinical Relevance- Results suggested that single-plane fluoroscopic analysis performed by use of CT-derived bone models is a valid, noninvasive technique for accurately measuring 3-D femorotibial poses in dogs.

Objective-To evaluate intra-articular autologous protein solution (APS) for the treatment of osteoarthritis in horses. Animals-40 client-owned horses with naturally occuring osteoarthritis. Procedures-APS was generated from a dual-device system that concentrated plasma and WBC proteins and enriched platelet growth factors. Horses were randomly assigned to receive an intra-articular injection of 5 mL of saline (0.9% NaCl) solution (n = 20) or APS (20), exercised on a treadmill, and evaluated on the basis of lameness grades, kinetic gait analysis, joint circumference, and range of motion for 14 days. Horses that received saline solution were administered APS at termination of the study, and clients scored horses for lameness and discomfort before, 12 weeks after, and 52 weeks after the APS injection. Results-The APS group had significant improvements in lameness grade, asymmetry indices of vertical peak force, and range of joint motion by 14 days, compared with baseline or control group values. No adverse effects associated with APS treatment were evident. Clients assessed lameness and comfort as improved at 12 and 52 weeks. The APS had greater likelihood (OR, 4.3 to 30.0) of a therapeutic response in horses with a lameness score < 4, < 10% vertical force asymmetry, or absence of marked osteophyte formation, subchondral sclerosis, or joint space narrowing. Concentration of interleukin-1 receptor antagonist in APS was 5.8 times that in blood. Conclusions and Clinical Relevance-Intra-articular administration of APS can be considered an effective treatment option for equine osteoarthritis, with the potential for disease-modifying effects.

The objective of this study was to evaluate a novel accelerometer-based sensor system, the Walkabout Portable Gait Monitor (WPGM), for use in kinetic gait analysis of dogs. The accelerometer was compared to the common reference standard of force platform analysis. Fifteen client-owned, orthopedically sound dogs of various breeds underwent simultaneous force platform and accelerometer gait trials to measure peak vertical forces (PVFs). The agreement between PVF for the accelerometer and force platform was measured using concordance correlation coefficient (CCC) and was found, overall, to be moderate [CCC = 0.51; 95% confidence interval (CI): 0.46 to 0.56]. The agreement between PVF for the accelerometer and force platform for the forelimbs was positive and substantial (CCC = 0.79; 95% CI: 0.74 to 0.84) and for the hind limbs was positive and low (CCC = 0.34; 95% CI: 0.29 to 0.38). As measured by the accelerometer, PVF was systematically higher than as measured by the force platform (forelimbs 55.3 N, hind limbs 144.3 N). It was also found that, when positioned over the lumbar spine, the WPGM cannot measure PVF of the individual forelimbs and hind limbs, which limits its use as a clinical tool to measure kinetic variables in dogs.