Sonographic observations were made of the image mean gray scale (MGS) of the flexor tendons and ligaments in the left and right metacarpal regions of each of 10 clinically normal horses. In images made in the dorsal and sagittal planes, the MGS was measured at multiple sites in the superficial digital flexor tendon (SDFT), deep digital flexor tendon (DDFT), accessory ligament (AL), and suspensory ligament (SL), and at single sites in the medial and lateral limbs of the SL, and the palmar ligament. Relative sonographic brightness of each tendon and ligament was calculated by dividing the value of its MGS by the mean value for the MGS of images of 3 soft tissue equivalent phantoms. When a multivariate repeated-measures of ANOVA of the relative brightness values was statistically significant (P < 0.05), Tukey's method of multiple comparisons was used to determine which values were significantly different from each other. In the dorsal plane, the SL was significantly brighter than the DDFT, SDFT, and AL; relative brightnesses of the DDFT and SDFT were similar, as were those of the SDFT and AL. In the sagittal plane, the SL again was the significantly brightest structure, followed by the Al, and similar brightnesses of the DDFT and SDFT. In dorsal images made 25 cm distal to the accessory carpal bone, relative brightnesses of the SDFT, DDFT, and the medial and lateral limbs of the SL were similar. In images made 30 cm distal to the accessory carpal bone, relative brightness of the palmar ligament was significantly (P < 0.05) less than that of the SDFT and DDFT in the dorsal plane, but not in the sagittal plane, where it was significantly greater. Relative brightness values represented a unique sonographic characteristic of each structure and, in the future, may provide further insights into tendon and ligament structure and function.

In recent years, exercise on a water treadmill has come to have great relevance in rehabilitation and training centres for sport horses. Its use exploits certain physical properties of water, related to the fundamental principles of hydrodynamics, such as buoyancy, viscosity, hydrostatic pressure, and water temperature. These properties together with deliberate specification of the depth of the water and the velocity of the treadmill provide a combination of parameters that can be varied according to the purpose of the rehabilitation or training programme, the disease to rehabilitate, or the healing phase. In the current article, kinematic adaptations to exercise on a water treadmill and the direct application of such exercise to the rehabilitation of superficial and deep digital flexor tendon and accessory ligament injuries and back and joint diseases are described.

OBJECTIVE To identify radiographic locations of soft tissue attachments in the tarsal region of horses and describe any variability in the gross anatomy of those attachments. SAMPLE 15 cadaveric limbs from 8 adult horses. PROCEDURES 8 limbs were used for dissection and radiography of soft tissue structures, with metallic markers used to identify radiographic locations of soft tissue attachments. The remaining 7 limbs were used to evaluate anatomic variations in the insertion of the tendon of the fibularis tertius muscle. A consensus list of preferred radiographic views for evaluating each soft tissue attachment was created. RESULTS The dorsoplantar, dorsoproximolateral-plantarodistomedial oblique (35° proximal and 45° lateral), dorsoproximomedial-plantarodistolateral oblique (10° proximal and 15° medial), and plantaroproximal-plantarodistal oblique (70° proximal; flexed) views were preferred for evaluating the collateral ligaments. The standard oblique views and plantaroproximal-plantarodistal oblique (70° proximal; flexed) view were preferred for evaluating the tendinous attachments of the gastrocnemius and superficial digital flexor muscles. All 4 standard views were necessary for evaluating the tendinous attachments of the cranial tibial and fibularis tertius muscles, the dorsal tarsal ligament, and the origin of the suspensory ligament. Three configurations of the insertion of the fibularis tertius tendon were identified grossly. In limbs with osteoarthritis of the distal tarsal joints, the dorsal tarsal ligament firmly adhered to the centrodistal tarsal joint. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that attachments of soft tissue structures in the tarsal region of horses were in distinct radiographically identifiable locations and that visualization of individual soft tissue attachments could be optimized with certain radiographic views, including some nonstandard views.

OBJECTIVE To evaluate the elastic modulus of various ligaments of the forelimbs of cadaveric horses. SAMPLE 408 ligaments from 37 forelimbs of 10 Thoroughbred cadavers and cadavers of 9 other horse breeds. PROCEDURES Collateral ligaments and straight and oblique sesamoid ligaments were harvested from the proximal interphalangeal, metacarpophalangeal, carpal, and elbow joints of both forelimbs of all 19 horses. Ligament dimensions were measured, and the elastic modulus was determined by tensile testing the ligaments with a strain rate of 1 mm•s(-1). RESULTS Elastic modulus of the ligaments differed significantly among joints. Highest mean ± SE elastic modulus was for the medial collateral ligament of the metacarpophalangeal joints of Thoroughbreds (68.3 ± 11.0 MPa), and the lowest was for the lateral collateral ligament of the elbow joints of other breeds (2.8 ± 0.3 MPa). Thoroughbreds had a significantly higher elastic modulus for the collateral ligaments of the proximal interphalangeal and metacarpophalangeal joints, compared with values for the other breeds. There was large variation in elastic modulus. Elastic modulus was negatively affected by age. In the ligaments in the distal aspect of the forelimbs, elastic modulus was negatively affected by height at the highest point of the shoulders (ie, withers). CONCLUSIONS AND CLINICAL RELEVANCE Cross-sectional area and elastic modulus of collateral ligaments in the forelimbs of equine cadavers differed between breeds and among joints, which may have been reflective of their relative physiologic function under loading during exercise.

OBJECTIVE To evaluate the effects of successive large-segment tracheal resection and anastomosis on tracheal diameter and position of lobar bronchi in dogs. ANIMALS 5 adult Beagles. PROCEDURES Right lateral radiographs were obtained for all dogs and used to measure tracheal length. Dogs were then euthanized, and successive segmental tracheal resections (intervals of 10% from 20% to 50% of the tracheal length), each of which was followed by anastomosis, were performed in each cadaver. Tracheobronchoscopy was performed before the first tracheal resection and after each of the anastomoses to evaluate tracheal diameter and changes in position of lobar bronchi. RESULTS Tracheal diameter was minimally affected by resections up to 50% of the tracheal length. Diameter of the trachea and position of bronchi were not affected by resection of 20% of the tracheal length. Changes in the position of various lobar bronchi were detected after resection of 30% of the tracheal length. CONCLUSIONS AND CLINCIAL RELEVANCE In this study, tracheal resections of 20% of the tracheal length were accommodated, possibly as a result of stretching of the annular ligament. Resections of ≥ 30% of the tracheal length altered the position of lobar bronchi. Clinical effects, if any, attributable to these changes in bronchial position remain to be elucidated.

Objective—To determine the microvascular anatomy of the suspensory ligament of the forelimb of horses. Sample—17 cadaveric forelimbs from 9 adult horses with no known history of forelimb lameness. Procedures—The median artery of the forelimb was cannulated proximal to the antebrachiocarpal joint and injected with contrast medium for CT evaluation of the gross vasculature (n = 2) or India ink to evaluate the microvasculature (12). Routine histologic evaluation was performed on an additional 3 forelimbs to confirm the microvascular anatomy. Results—The vascular supply of the suspensory ligament of the forelimb originated from branches of the medial and lateral palmar and palmar metacarpal vessels as well as the proximal and distal deep palmar arches. An abundant, longitudinally oriented microvascular supply was evident throughout the length of the suspensory ligament without distinct variation among the proximal, midbody, and distal regions. The intraligamentous blood supply originated from a periligamentous vascular plexus that surrounded the suspensory ligament throughout its length. Histologic findings indicated the presence of a periligamentous connective tissue plexus, which contained vessels that penetrated and anastomosed with an extensive network of intraligamentous vessels throughout the length of the suspensory ligament. Conclusions and Clinical Relevance—The suspensory ligament of the equine forelimb had an abundant intraligamentous microvascular supply throughout its entire length. The absence of an obvious hypovascular area suggested that regional variations in healing rates of the suspensory ligament are not associated with the microvascular anatomy.

This study evaluated two different surgical techniques for the treatment of palmar annular ligament desmitis (PAL) in horses. The group 1 (G1) consisted of 11 Thoroughbred submitted to desmotomy, and G2 of 22 horses that underwent PAL desmectomy. There was no statistically significant difference between mean palmar annular ligament thickness in both groups evaluated (p = 0.800). In this study, the horses of G1 had 12 times more chance to return to physical activity, when compared to animals of G2 (p = 0.033; O.R. = 12.0; C.I.95% = 1,142-126,122). Desmectomy was more efficient in promoting the resolution of the injury and the return to sports activity.

Sonographic observations were made of the image mean gray scale (MGS) of the flexor tendons and ligaments in the left and right metacarpal regions of each of 10 clinically normal horses. In images made in the dorsal and sagittal planes, the MGS was measured at multiple sites in the superficial digital flexor tendon (SDFT), deep digital flexor tendon (DDFT), accessory ligament (AL), and suspensory ligament (SL), and at single sites in the medial and lateral limbs of the SL, and the palmar ligament. Relative sonographic brightness of each tendon and ligament was calculated by dividing the value of its MGS by the mean value for the MGS of images of 3 soft tissue equivalent phantoms. When a multivariate repeated-measures of ANOVA of the relative brightness values was statistically significant (P < 0.05), Tukey's method of multiple comparisons was used to determine which values were significantly different from each other. In the dorsal plane, the SL was significantly brighter than the DDFT, SDFT, and AL; relative brightnesses of the DDFT and SDFT were similar, as were those of the SDFT and AL. In the sagittal plane, the SL again was the significantly brightest structure, followed by the Al, and similar brightnesses of the DDFT and SDFT. In dorsal images made 25 cm distal to the accessory carpal bone, relative brightnesses of the SDFT, DDFT, and the medial and lateral limbs of the SL were similar. In images made 30 cm distal to the accessory carpal bone, relative brightness of the palmar ligament was significantly (P < 0.05) less than that of the SDFT and DDFT in the dorsal plane, but not in the sagittal plane, where it was significantly greater. Relative brightness values represented a unique sonographic characteristic of each structure and, in the future, may provide further insights into tendon and ligament structure and function.