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OBJECTIVE To investigate the effects of a small sensor attached to the pastern region of a forelimb on lameness detection and quantification with a portable inertial sensor–based system (PISBS) for lameness detection and quantification in horses. ANIMALS 20 adult horses (body weight, 410 to 650 kg) with no visible lameness at the walk. PROCEDURES In a crossover study design, horses were evaluated at the trot twice using the PISBS with the gyroscope alternately attached to the right forelimb pastern region (as recommended by the manufacturer) or to the left forelimb pastern region (with the sensor flipped 180° on the frontal plane relative to the standard position). Agreement between the 2 instrumentation approaches was investigated graphically and by repeated-measures ANOVA, Pearson correlation analysis, and Bland-Altman analysis. RESULTS No effects of instrumentation of a forelimb with the gyroscope were detected on the lame limb or limbs or on lameness severity. Attachment of the gyroscope to a forelimb had no effect on forelimb or hind limb lameness (ie, did not cause or mask lameness) as measured with the PISBS. CONCLUSIONS AND CLINICAL RELEVANCE Instrumentation of a forelimb with a lightweight gyroscope for lameness evaluations with a PISBS had no effects on lameness measurements in horses. Results suggested that, when indicated, the gyroscope can be attached (while flipped 180° on the frontal plane relative to the standard position) to the left forelimb (rather than the right forelimb).

Deep digital sepsis (DDS) as applied to bovine lameness is not strictly defined, but for the purposes of this discussion will include infection of bones, joints, bursa or tendon sheaths within the foot. Often, there are infections of several of these structures in the same digit. Such infections are most commonly due to extension of infection from more superficial layers as in the case of advanced sole ulceration, white line disease or toe tip necrosis, but can be secondary to direct penetration or trauma. Deep digital sepsis should be suspected when lameness is severe coupled with 1 or more of the following: asymmetrical swelling of the foot, swelling extending proximal to the pastern region, and a duration of severe lameness of >2 weeks. Lameness associated with deep digital sepsis (DDS) is severe and requires aggressive and somewhat expensive therapy to resolve. Recognition of the development of DDS is critical to appropriate management of a lameness case. Description of therapeutic options will be provided in another paper in this volume (see Therapy of Deep Digital Sepsis)., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2019

Recognition of artefacts is an essential component of the accurate interpretation of diagnostic images. This study aimed to investigate the presence of magic angle effect in the superficial digital flexor tendon (SDFT) in the equine proximal pastern region. The proximal pastern of four cadaver limbs was imaged using a 0.27 Tesla magnet with high-resolution sequences that are commonly utilised in clinical equine practice. The limbs were imaged in a neutral position and positions that simulated the horse 'leaning in', 'leaning out' and having internal and external rotation of the distal limb. Signal intensity changes in the SDFT were described and compared. The simulated 'leaning in' and external rotation positions resulted in increased signal intensity in the axial and middle thirds of the lateral half of the SDFT on sequences with short echo times. The simulated 'leaning out' and internal rotation positions resulted in increased signal intensity in the axial and middle thirds of the medial half of the SDFT on sequences with short echo times. These signal intensity changes did not occur or were only mild and inconsistent on T2 fast spin echo sequences with longer echo times. The increases in signal intensity in the SDFT are consistent with a position-induced magic angle artefact that has been noted in clinical cases. Attention to positioning of the equine distal limb is essential during clinical imaging; radiologists should be aware of position-induced artefacts to ensure accurate image interpretation.

Summary Reasons for performing study: ‘Soring’ is the term used to describe the application of an irritant to the distal forelimbs of gaited horses with the sole intent of inflicting pain and inducing altered gait, illegally practiced in Tennessee Walking Horses. Objective methods for the detection of limb pain due to this practice are, however, lacking. Objectives: To assess whether Tennessee Walking Horses respond to manual pressures ≤10 kg/cm2 and to establish reference mechanical nociceptive thresholds (MNTs) within the pastern region. Methods: In 25 mature Tennessee Walking Horses in which no irritant had been applied, MNTs were evoked by a pressure algometer at 4 sites within the pastern region of each thoracic limb by 6 different examiners. The effects of age, sex, weight, height at withers, exercise and hand dominance of the examiners on MNTs were assessed. Correlations between the horse's perceived mental status, tolerance to the procedure and MNT values were also evaluated. Results: Mechanical nociceptive thresholds ≤10 kg/cm2 were observed in 20% of measurements, of which the mean ± s.d. MNT was 9.5 ± 0.3 kg/cm2. Within 4 pastern sites, the palmar region had the lowest reference MNT value of 19.5 ± 3.6 kg/cm2. Subject status, exercise, hand dominance, horse mental status and horse procedure tolerance did not significantly affect MNT values. Conclusions: Reference MNTs of the pastern region of nontreated Tennessee Walking Horses provide an objective standard for the evaluation of those potentially applied irritant. Potential relevance: Pressure algometry, in lieu of digital pressure, can quantify mechanical pressure applied during inspections to detect irritant therapy and provide consistency between examiners.

The causes, clinical signs and various approaches to treatment of injuries involving the foot and pastern regions are reviewed, and the prognosis for each type of injury is discussed.