Case Study: Detection of low level bilateral suspensory desmitis with the aid of objective measurement

By Equinosis Certified Practitioner Mitch Byrd, DVM | Updated on September 06, 2022 | Bilateral Lameness, M Byrd

Signalment:

14yr Warmblood mare showing upper-level dressage.

March 8, 2019

Previous RF check ligament injury. The horse presented March 8, 2019 with a complaint of performance limitations. The horse was examined, and a CBC/Chem and metabolic panel were run with no significant findings.

April 25, 2019

The horse was re-evaluated after the owner was concerned the horse had tied up. Muscle palpation was normal. CK was mildly elevated. Hip high RH at walk, 2/5 RH at trot on grass. Upper limb flexions were positive on both rear limbs.Suspensory compressions on the hindlimbs were equivalent.

April 27, 2019

Radiographs of the hocks were performed. Bilateral changes at distal joints were noted (RH > LH). The lower hock joints were treated with Betamethasone.

May 9, 2019

The owner reported the horse was flat in work and not pushing through from behind.

A visual exam was performed without Lameness Locator. The horse was observed to be RF/RH in straight line trot. RF distal limb flexion was moderately positive. RH upper and lower limb flexions 2/5. LH upper and lower limb flexions 1/5 and made RH unsoundness worse. LH anteflexion - exacerbated RH unsoundness.

The following blocks were performed.

RF coffin joint block (w Betamethasone) IA- No change.
RF carpal canal block- moderate improvement RF unsoundness.
RH low 6-point block- No improvement.
RH lateral plantar block- Significant improvement.

May 14, 2019

Work up with Lameness Locator. The horse had been rested.

A RF unsoundness was observed visually with no specific hindlimb asymmetry noted. The RF distal limb flexion was moderately positive, and the RH suspensory pressure test was significantly positive.

Baseline Straight

Fig. 2 - RF distal limb flexion was mildly positive.

Fig. 3 - RH suspensory pressure was significantly positive first few strides.

Fig. 4 - Direct infiltration of the RH proximal suspensory was performed. The horse developed a consistent mild LH pushoff lameness (Diff Max Pelvis -3.1 mm). The RF impact lameness was also reduced.

Fig. 5 - The trial was repeated to confirm results. The LH pushoff lameness was stable and no further change in the RF was noted.

Fig. 6 - A direct infiltration of the LH proximal suspensory was then performed. At 20 minutes, the LH pushoff lameness was eliminated.
Repeat trial after LH PSL to confirm results.

Fig. 7 - A repeat trial showed a mild switch of sides back to the RH, but was within reference range. The RF remained quite mild and was not further pursued.

Imaging

Ultrasound examination of hind suspensory ligaments demonstrated branch and mid body lesions LH and origin lesions RH. MRI was suggested but declined.

Treatment

Shockwave, walk under saddle, small paddock, Adequan.

Follow up

The mare was monitored frequently through rehabilitation, assessed on the straight, lunge and under saddle. By September 2019 the horse was in steady trot work and the rider reported the horse felt strong and even. She was evaluated as sound under saddle with improved responses to palpation and flexion (fig. 8).

She gradually returned to normal work. The horse reinjured the RF check ligament in April 2022 and is currently rehabbing.

Conclusion

On the day of the last examination, it can be seen,represented by these Lameness Locator reports,that the horse was not presenting outwardly lame in the hindlimbs.

The history of treatment and treatment failures combined with response to suspensory provocation tests dictated the approach taken during this examination. Prior exams did not make use of the Lameness Locator, and, in hindsight, I was not getting the complete picture.

Without the use of objective measurement, I would not have been confident calling the subtle switches of side in hindlimb asymmetry. The switch from symmetrical to LH asymmetry with a RH PSL block, back towards symmetry with a LH PSL block would not have been appreciated with confidence.

This is a good example of how bilateral lameness, especially mild bilateral lameness, can be masked when the level of lameness in each limb is fairly equal. This can be a conundrum for both visual assessment and inertial sensor measurement. However, the inertial sensors aided the examination by detecting the subtle but significant changes in hindlimb lameness with diagnostic analgesia.

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