Biomechanical data scaled to horse size

We are excited to announce a significant update to your Sleip data: anatomical scaling.  This industry-first feature factors in horse size, straight from video, when calculating asymmetry data. Here's why it matters:

Improved precision and clinical relevance

• Tailored to anatomy: Unlike previous methods, anatomical scaling considers the horse's size, providing a more intuitive correlation between measured asymmetry and horse size.
• Better consistency: The new method scales impact and push-off asymmetry to the horse's dimensions, leading to a more consistent representation of data for horses with both small and large movement patterns.
• Enhanced decision-making: With asymmetry measurements scaled to horse size, comparability of asymmetry severity increases and you can make informed decisions with greater confidence.

Towards a new standard

When performing movement asymmetry measurements of trotting horses it is common to quantify the vertical movement of the head and pelvis. To enable comparisons between large and small horses, asymmetry values shown by Sleip have been scaled based on the total vertical movement of the head and pelvis when trotting.

However, in cases of "small movers" or horses with limited vertical movement relative to their size, significant asymmetry may be observed without corresponding force compensation. In short, this results in measurements that indicate a comparatively greater asymmetry. Analysis of these horses might then indicate a more severe asymmetry than reflected by their weight redistribution from the lame limb.

With the new anatomical scaling developed by Sleip, asymmetry levels are adjusted based on horse size. This improvement makes it more intuitive to interpret gait analysis data, as the user does not have to factor in whether the horse is a big or small mover.  

Large movers versus small movers

Observe the vertical movement of the head of the two different horses. Look at the movement of the heads against the distant background to gauge the range of the movement.  The horse on the left has a more prominent vertical range of movement. 

Anatomical scaling explained

Sleip uses AI to measure asymmetry variables from horses in motion. To do this, we rely on video data recorded using the Sleip app. Since video is a dimensionless type of data, the calculated asymmetry variables need to be rescaled in order to produce repeatable and reliable data. Scaling is also needed to compare asymmetry degrees between small and large horses. 

The current gold standard for this rescaling relies on the principle that the vertical movement of a horse in trot can be divided into (at least) two main components or harmonics (Fig.1). Think about these harmonics as musical notes - they have a specific frequency and amplitude. What we measure as the vertical displacement of the horse is a sum of these two harmonics.

Fig.1

• The first harmonic, which is the “lame” component of the movement, explains the horse's lameness. 
• The second harmonic, which is the “sound” component of the movement, has an amplitude that relates to the size of the horse and is constant, independent of the lameness status of the horse. Therefore, the amplitude of this harmonic is commonly used to estimate the horse's size. 

The new scaling method developed by Sleip (Fig.2) uses the actual anatomical size of the horse to rescale the asymmetry data to provide a measurement that better correlates with the degree of observed asymmetry.

• Typically (but not always) small horses exhibit smaller movements than large horses. With the new anatomical scaling, asymmetry values become more comparable between different horse sizes.
• In the case of horses with very small vertical displacement of the head or the pelvis, a movement relative asymmetry can appear very disproportionate compared to the actual movement. The new anatomical scaling mitigates this issue.

Fig.2