Use and repeatability of 3D light-scanning to assess external profile and symmetry in horses

Equine epaxial muscle size, thoracolumbar profile and symmetry in horses is of clinical interest due to relationships with pain and pathology. A flexible-curve rulers is reliable objective measures of thoracic profile, however 3D light-scanning offers a potential non-contact alternative method to record cross sectional area (CSA) of the region. 3D light-scans of the thoracic epaxial region were taken from ten endurance horses (7 geldings, 3 mares; 8±2 years). Total CSA of the combined epaxial musculature, using proprietary software, was calculated at scapula and T18 levels (depth: 15 cm). Intra and inter-rater (n=3) reliability was assessed using Friedman’s analyses and Wilcoxon rank tests (three repeated measures). Intraclass correlation estimates (ICC±95% confidence intervals (CI)) were calculated (mean-rating, absolute-agreement, 2-way mixed-effects model). Paired t-tests assessed differences between right and left areas. No significant differences existed for transverse plane-cuts (scapula, T18 P>0.05). Right and left areas were significantly different at the withers (P<0.0004) with the right increased (60.9%, P=0.47) but not significantly different at T18 (P=0.49). No differences existed for different plane-cuts of the same horse (P=0.53; ICC: 0.76; CIs: 0.43-0.92). While reliability was reduced between all raters (P=0.02; ICC: 0.70; CIs: 0.56-0.82), no significant differences occurred between assessors (n=2) experienced in using the software (P=0.88; ICC: 0.90; CIs: 0.82-0.95). Intra-rater reliability for assessing thoracic profile and inter-rater reliability with experienced analysts was good/excellent. The results suggest 3D light-scanning is an objective, non-invasive method to record size and symmetry of the epaxial region in horses and warrants validity testing against gold-standard imaging.Characteristics of horses with impinging dorsal spinous processesR. Brassington1, R. Hardy1 and T. Bye21University Centre Bishop Burton, Bishop Burton College, York Road, HU17 8QG, United Kingdom, 2Loughborough University, Epinal Way, Loughborough, LE11 3TU, United Kingdom; [email protected] dorsal spinous processes are a common cause of pain and loss of performance in sports horses. This cross-sectional study aimed to identify factors common in horses diagnosed with IDSP. An online survey, aimed at horse owners, was circulated via social media; data were collected for 260 horses with a diagnosis of IDSP. Chi squared testing was used to determine if any characteristics (age, competitive discipline, breed type, area of spine affected) were overrepresented in the group, or had any relationship to one another. 59% of horses had pathology in the caudal thoracic (T10-T18) region, significantly more than any other region of the spine (χ2=181.5, df=3, P<0.001). There was a significant effect of age (χ2=223.4, df=5, P<0.001) with 41% of horses diagnosed between 7-10 years of age and 93% diagnosed between 3-14 years of age. There was a significant association between age at diagnosis and vertebrae affected (χ2=30.2, df=15, P=0.01); the 3-6 year age group had more cases in cranial thoracic (T1-T9) and lumbar regions, the 7-10 year group had more cases in the caudal thoracic region. Breed type was identified as a significant factor (χ2=68.9, df=4, P<0.001), with more Thoroughbreds (35%) and Warmbloods (27%) in the group than expected. The discipline the horse was used for was also a significant factor (χ2=25.7, df=4, P<0.001), with more dressage horses (28%) diagnosed than expected. The characteristics common in horses diagnosed with IDSP represent a range of factors which may contribute to the pathogenesis and progression of the condition.