Pressure pain mapping of equine distal joints: feasibility and reliability.

Background: Osteoarthritis is a prevalent degenerative joint disease initiating chronic pain and lameness in horses. While several objective gait analysis systems have been developed and validated to quantify lameness severity in horses, methods to evaluate whether peripheral sensitization contributes to the pain experienced are missing. Objectives: To evaluate whether periarticular pressure pain mapping could be proposed as an auxiliary assessment tool in horses. Specific aims were to evaluate the feasibility and intra- and inter-rater reliability of pressure pain thresholds (PPT) determination at sites overlying the distal thoracic limb joints of clinically healthy horses. Study design: Prospective, randomized validation study. Methods: For feasibility assessment, PPT were measured with a hand-held digital algometer at six periarticular landmarks (2 sites per joint, 3 joints) bilaterally on the distal thoracic limb of 40 healthy horses (20 warmblood and 20 Freiberger). The joints tested were the metacarpophalangeal, on the latero-palmar and dorsal aspects (L-MCP and D-MCP), the proximal interphalangeal, on the dorsal and palmar aspect (D-PIP and P-PIP) and the distal interphalangeal, on the dorsal and lateral aspect (D-DIP and L-DIP). A feasibility score, ranging from 0 to 5, was attributed to each testing session. For intra- and inter-rater reliability assessment, L-MCP and D-MCP were selected to be tested again at 2 weeks intervals in 20 out of the 40 horses. Data were analyzed using a mixed-effect linear model to test differences in threshold per site and limb. Intra- and inter-rater correlation was calculated. Bland-Altman plots were performed to evaluate the variability of the measures. Results: The procedure was considered feasible (score <2) in 95% of horses (95% CI 88%-100%). Overall, median [interquartile range (IQR)] PPT was 9.4 (7.5-11.3) N. No significant side differences were found. P-PIP and D-DIP recorded significantly lower PPT (p < 0.001 and p = 0.002, respectively) than L-MCP. Median (IQR) were 9.9 (7.3-12.4) N, 8.4 (6.1-10.5) N and 9.0 (7.4-10.6) N for L-MCP, P-PIP and D-DIP, respectively. The intra-rater agreement was 0.68 (95% CI 0.35-0.86) for L-MCP, and 0.50 (95% CI 0.08-0.76) for D-MCP. Inter-rater agreement was 0.85 (95% CI 0.66-0.94) for L-MCP and 0.81 (0.57, 0.92) for D-MCP. Main limitations: Evaluation of feasibility was performed only for distal thoracic limbs joints; no data are provided for hind limbs or proximal joints. Only warmblood and Freiberger horses were included. Intra- and inter-rater reliability assessments were performed exclusively on data collected at the MCP joint. Conclusion: Pressure pain mapping of distal thoracic limb joints was feasible in horses. Local sensitivity differed among sites and no side differences were noticed. Data collected from the MCP joint suggest highly variable, subject dependent intra-rater reliability, ranging from poor to good, and good to excellent inter-rater reliability. Further studies evaluating pathologic vs. healthy joints are needed before recommendations can be made about clinical usability and diagnostic validity.

Validation of Alogo Move Pro: A GPS-Based Inertial Measurement Unit for the Objective Examination of Gait and Jumping in Horses.

Quantitative information on how well a horse clears a jump has great potential to support the rider in improving the horse's jumping performance. This study investigated the validation of a GPS-based inertial measurement unit, namely Alogo Move Pro, compared with a traditional optical motion capture system. Accuracy and precision of the three jumping characteristics of maximum height (Zmax), stride/jump length (lhorz), and mean horizontal speed (vhorz) were compared. Eleven horse-rider pairs repeated two identical jumps (an upright and an oxer fence) several times (n = 6 to 10) at different heights in a 20 × 60 m tent arena. The ground was a fiber sand surface. The 24 OMC (Oqus 7+, Qualisys) cameras were rigged on aluminum rails suspended 3 m above the ground. The Alogo sensor was placed in a pocket on the protective plate of the saddle girth. Reflective markers placed on and around the Alogo sensor were used to define a rigid body for kinematic analysis. The Alogo sensor data were collected and processed using the Alogo proprietary software; stride-matched OMC data were collected using Qualisys Track Manager and post-processed in Python. Residual analysis and Bland-Altman plots were performed in Python. The Alogo sensor provided measures with relative accuracy in the range of 10.5-20.7% for stride segments and 5.5-29.2% for jump segments. Regarding relative precision, we obtained values in the range of 6.3-14.5% for stride segments and 2.8-18.2% for jump segments. These accuracy differences were deemed good under field study conditions where GPS signal strength might have been suboptimal.

Simulated Kick Injury to the Mandible in Horses: Study of Fracture Configurations and Physical Parameters of the Impact.

OBJECTIVE: The goal of this study was to generate mandibular fractures in three regions of the diastema using a metal impactor to simulate a kick from a horse and to determine the mean deceleration in the initial phase of the impact event, the maximum contact force, the impact energy necessary to create a fracture and the duration of the impact. STUDY DESIGN: Thirty heads of horses aged between 5 and 20 years and euthanatized for various reasons were used. The heads were attached to a steel bar at the occiput at an axial angle of 45 degrees so that the body of the mandible was positioned horizontally and directly under the trajectory of the impactor. A 2 kg solid impactor was dropped with velocities of 6 to 14 m/s to simulate a kick from a horse. The impact was recorded using a high-speed video camera with a frame rate of 30,000 frames per second. Radiographs of the heads were obtained before and after the simulated kick. RESULTS: Mandibular fractures with configurations similar to those seen in clinical practice were generated at all three locations. The mean deceleration increased with impact velocity and with more cranially located impact positions. Absorbed energy increased with increasing impact velocity when no fracture was generated. CONCLUSION: The susceptibility to experimental fracture of the diastema increased from rostral to caudal locations, which is most probably caused by decreasing mandibular bone strength and an increase in the curvature at the lateroventral aspect of the mandible in that region. Physical parameters depended on fracture occurrence and type.

Long-term clinical and radiographic results after lag screw ostheosynthesis of short incomplete proximal sagittal fractures of the proximal phalanx in horses not used for racing.

OBJECTIVE: To determine long term outcomes of nonracing equines athletes treated for short incomplete proximal sagittal fractures of the proximal phalanx (SIPSFP1) by lag screw fixation. STUDY DESIGN: Retrospective study. SAMPLE POPULATION: Thirty-one horses. METHODS: Medical records from horses with an SIPSFP1 (2008-2014) were reviewed. Long-term (≥12 months) outcomes were assessed with telephone interviews and clinical and radiographic examinations. RESULTS: Warmblood was the predominant breed in cases included in the study. Among horses with long-term interview information, 27 of 31 returned to previous athletic activity level. In total, 15 horses with 19 fractures had clinical and radiographic assessment after a minimum of 12 months. Among those, nine of 15 horses were sound at the trot, and six of 15 were mildly lame. Complete radiographic healing was confirmed in six limbs, and the facture line was evident in 13. The position of the proximal screw was not associated with radiographic fracture healing or return to soundness. CONCLUSION: Most horses treated for SIPSFP1 with lag screw fixation returned to previous activity levels, although radiographic fracture healing remained incomplete 12 months or more after surgery. CLINICAL SIGNIFICANCE: Lag screw fixation is a valid treatment for horses not used for racing that are experiencing an SIPSFP1 and results in a high rate of return to intended use, although complete radiographic fracture healing cannot be expected.