Could smartphones help in assessing hindlimb lameness in horses?

Study shows smartphones are capable of providing data useful in supporting a vet carrying out a lameness assessment.
The placement of the smartphone during data collection. Photo: Marunova et al.

Smartphones with an appropriate app show promise as a useful tool in helping to evaluate hindlimb lameness in horses, according to researchers.

Eva Marunova and her fellow researchers, in a study published in the journal Animals, reported that a smartphone successfully detected pelvic movement asymmetry, with greater levels of asymmetry recorded in horses with a greater degree of lameness.

“Although the use of a smartphone measuring only the symmetry of the pelvis cannot replace a full lameness examination, it presents a useful adjunct to subjective evaluation alone,” the study team concluded.

Smartphones may also prove to be useful in tracking progress after a treatment or during the rehabilitation process, they said.

The study team said the assessment and grading of equine lameness can be a challenge for veterinarians, since they rely on subjective visual recognition of changes in movement. Agreement has been reported to be poor, even for experienced equine veterinarians, they noted.

Their study involved 301 horses assessed at a veterinary hospital in Switzerland, all assigned a lameness grade on a scale of 0 to 10 by a board-certified veterinary surgeon.

For the experiment, each horse was equipped with an off-the-shelf iPhone6, which comes with an internal inertial measurement unit.

The smartphone was attached to a specially modified Velcro pad that was fixed centrally over the sacrum of each horse via double-sided tape. The Velcro pad had an 11-mm-wide strip on the left side of the pad. This guided placement of the phone so that while the pad was attached centrally on the horse, the smartphone was placed 11 mm to the right of the centre, ensuring that its in-built accelerometer was positioned directly above the horse’s midline.

The researchers used an app called SensorLog, available via the App Store. The software was configured to collect three-axis acceleration as well as orientation data, providing information on roll, pitch and yaw.

Each horse was evaluated only once under the following protocol: The horse was trotted by the same handler in-hand in a straight line on a hard surface for about 25 metres away from, and then towards, the assessing veterinarian.

The smartphone was then removed from the horse and the veterinarian assigned his subjective lameness grade before uploading the data from the smartphone to a Windows-based computer for asymmetry analysis.

The study took place over three years.

The visual assessment by the veterinarian classified 36% of the 301 horses as non-lame, with a grade of 0. Eighteen percent was classed as grade 1, 20% as grade 2, 11% as grade 3, 14% as grade 4: and 1% as grade 5. No horses were classified as grade 6 or above.

“Our results suggest that asymmetry values for all pelvic parameters, recorded by a smartphone, increase in line with higher lameness grades,” the study team reported.

Pair-wise comparisons revealed that in the majority of cases there were significant differences in the recorded objective parameters between different lameness grades. “These differences were, however, often not significant for pairs of lameness grades which were just one grade apart.”

“In general,” they concluded, “cut-off points calculated for quantitative measures of pelvic movement symmetry between lameness grades increased with the severity of lameness as scored subjectively by one veterinarian, and this is in line with previous studies.”

Although the smartphone cannot replace a full lameness examination, it may be useful in providing objective data to help veterinarians, they said.

“Ultimately, it may also be a cost-effective method for documenting progression of lameness or improvements after treatment or during rehabilitation. This aspect deserves further attention.”

The study team comprised Marunova, Leea Dod and Thilo Pfau, all with the Department of Clinical Science and Services at The Royal Veterinary College in England; and Stefan Witte, with the Schönbühl Veterinary Clinic in Urtenen-Schönbühl, Switzerland.

Marunova, E.; Dod, L.; Witte, S.; Pfau, T. Smartphone-Based Pelvic Movement Asymmetry Measures for Clinical Decision Making in Equine Lameness Assessment. Animals 2021, 11, 1665.

The study, published under a Creative Commons License, can be read here

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