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 characterize and compare gait variables in Doberman Pinschers with and without cervical spondylomyelopathy (CSM). ANIMALS 18 Doberman Pinschers (9 clinically normal dogs and 9 CSM-affected dogs). PROCEDURES A neurologic examination was performed on all dogs. The diagnosis of CSM was confirmed with MRI. Temporospatial and kinetic gait variables were measured by use of a pressure-sensitive walkway. Temporospatial variables evaluated included stance phase duration, swing phase duration, gait cycle duration, stride length, and gait velocity. Kinetic variables evaluated included peak vertical force and vertical impulse. Random-effects linear regression was used to determine the difference between CSM-affected and clinically normal dogs for each of the 7 variables. RESULTS Values for temporospatial variables were significantly smaller in the thoracic limbs of CSM-affected dogs, compared with values for the thoracic limbs of clinically normal dogs. For the kinetic variables, peak vertical force was significantly higher in the thoracic limbs than the pelvic limbs for all dogs. Vertical impulse values were higher in the thoracic limbs than the pelvic limbs. There were significant differences in mean vertical impulse between the thoracic and pelvic limbs for both groups. CONCLUSIONS AND CLINICAL RELEVANCE In this study, significant differences in temporospatial variables were identified between the thoracic limbs of clinically normal and CSM-affected dogs, with the values being smaller for the CSM-affected dogs than for the clinically normal dogs. A pressure-sensitive walkway may provide a valid, practical option for rapid, objective assessment of gait and response to treatment in dogs with CSM.

OBJECTIVE To develop a model of hip joint synovitis on the basis of intra-articular injection of a sodium urate suspension in dogs and to characterize associated gait changes. ANIMALS 6 healthy adult dogs. PROCEDURES Each dog was sedated, and synovitis was induced by injection of 1 mL of a sodium urate suspension (20 mg/mL) into the right hip joint under ultrasonographic guidance. Observational and instrumented gait analyses to determine temporospatial, kinetic, and kinematic variables were performed prior to and 4, 8, and 24 hours after sedation and synovitis induction. RESULTS Injection of a sodium urate suspension into the hip joint of healthy dogs resulted in lameness of the ipsilateral pelvic limb as determined by observational and instrumented gait analyses. For all dogs, lameness was clinically detectable within 1.5 to 2 hours after injection, reached its maximum intensity at 4 hours after injection, and had subsided by 24 hours after injection. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that injection of a sodium urate suspension into the hip joint of healthy dogs reliably induced synovitis and signs of pain and lameness in the ipsilateral pelvic limb that lasted 24 hours. This model can be used in conjunction with instrumented gait analysis to provide information on gait changes associated with hip joint disease and might be useful for evaluating the efficacy of analgesics or other interventions for the treatment of hip joint disease in dogs.