Saturday, July 2, 2022, 1:52 AM
Site: Equinosis Online Learning Portal
Course: Objective Lameness Measurement with the Equinosis Q For Veterinary Students (OLM - Veterinary Students)
Glossary: Encyclopedia

Pelvic Sensor

The pelvic sensor device contains an accelerometer that tracks vertical pelvic acceleration.


Right Forelimb Sensor

The right forelimb sensor device contains a gyroscope that measures angular velocity in the sagittal plane. It is used as an event marker to determine right forelimb stance. It is also used to calculate a median stride rate.


Soft Surface

If the foot creates a depression or a divot in the ground, the surface should be considered soft.  Soft preset surfaces = loose sand, grass/turf, soft/deep, mud, soft synthetic, soft (generic). 

Stabilizing the Lameness

Following viewing the initial baseline straight evaluation, repeat the trial to confirm stability of lameness measurements! 

  1. When beginning an evaluation, it is advised to perform two straight line trials one after the other to confirm results, and, if lameness present, a stable lameness. 
  2. Horses fresh out of a stall or off of a trailer may not always show a stable lameness on the first evaluation.  
  3. There is also a small window of expected trial-to-trial variability. However, significantly different results between two trials are indicative of an unstable lameness. 
  4. If two trials back to back do not yield similar results in limb, timing, and amplitude, it is recommended to exercise the horse, such as lunging, for a few minutes and evaluate again. 

Stride Plot

the graphical representations of the trial data.

Stride-by-stride variability

the variability of the lameness measure (Diff Max Head, Diff Min Head, Diff Max Pelvis, Diff Min Pelvis) from stride to stride over the course of a single data collection trial. Stride-by-stride variability is assessed in the Lameness Locator® report by comparing the standard deviation to the absolute value of the mean for that measure. If the standard deviation is significantly greater than the mean (currently this is arbitrarily set at 120% of the mean), the confidence in, or strength of evidence for, lameness (in limb, amplitude and/or timing) is reduced.


The Quantification (Q) Score

the Q score is a summary of the side, timing and amplitude of the asymmetry. 

  • There is one Q score for forelimb and a combined Q score for hind limb (one for the pushoff component and one for the impact component). 
  • Note that Q Scores have no +/- sign.  The limb and timing in stride cycle is described directly – i.e. L/R (for Left or Right) and Imp/Mid/Push (for Impact, Midstance, or Pushoff) in forelimb and Imp or Push for hind limb.  
  • Q Scores do not assess variability. The user should still inspect lameness metric standard deviations (or the Trial AIDE statements) to understand the stride by stride consistency of asymmetry, which contributes to the overall evidence of lameness.

Total Diff Head (Vector Sum)

Can be considered the amplitude of total head movement asymmetry, taking into account both Diff Max and Diff Min of the head. 

As the side and timing of forelimb lameness is dependent upon both Diff Max Head and Diff Min Head, this single variable can be more easily used to estimate the overall level of forelimb lameness. 

Total Diff Head is the Vector Sum of the mean Diff Max and mean Diff Min values, and is calculated using Pythagorean Theorem (a2 + b2 = c2), where a is the value of Diff Max head, b is the value of Diff Min head, and c is Vector Sum. (a) is plotted on the X axis, (b) is plotted on the Y axis, and the hypotenuse that forms that triangle is the Vector Sum. Total Diff Head is indicated by the RED ray on the forelimb plot.

The Total Diff Head (Vector Sum) reference range is 0 to 8.5mm. The upper reference range value of 8.5 is derived from the VS calculation when Diff Max Head and Diff Min Head are at their upper reference range values of |6|.   62+62=VS2

Trial Metadata

Owner, horse, and trial specific data (including date, time and type of trial conducted).

Trial-to-trial variability

Trial-to-trial variability = the variability of the mean lameness measure between two trials. I.e. is the measure repeatable? Trial-to-trial variability is assessed by comparing the lameness measures between two trials and whether they are within the 95% confidence intervals of repeatability.  If a particular measure in two back-to-back trials is not within the 95% CI, then that lameness is not stable.