P. Eksell

Kinematic evaluation of the back in the sport horse with back pain.

REASONS FOR PERFORMING STUDY Earlier studies have developed a clinical tool to evaluate objectively the function of the equine back. The ability to differentiate horses with back pain from asymptomatic, fully functioning horses using kinematic measures from this tool has not been evaluated. OBJECTIVES To compare the kinematics of the back at walk and trot in riding horses with back dysfunction to the same parameters in asymptomatic sport horses. METHODS The kinematics of the back in 12 horses with impaired performance and back pain were studied at walk and trot on a treadmill. Data were captured for 10 sees at 240 Hz. Range of movement (ROM) and intravertebral pattern symmetry of movement for flexion and extension (FE), lateral bending (LB) and axial rotation (AR) were derived from angular motion pattern data and the results compared to an earlier established database on asymptomatic riding horses. RESULTS At walk, horses with back dysfunction had a ROM smaller for dorsoventral FE in the caudal thoracic region (T13 = 7.50 degrees, T17 = 7.71 degrees; P<0.05), greater for LB at T13 (8.13 degrees; P<0.001) and smaller for AR of the pelvis (10.97 degrees; P<0.05) compared to asymptomatic horses (FE-T13 = 8.28 degrees, FE-T17 = 8.49 degrees, LB-T13 = 6.34 degrees, AR-pelvis = 12.77 degrees). At trot, dysfunctional horses had a smaller (P<0.05) ROM for FE at the thoracic lumbar junction (T17 = 2.46 degrees, L1 = 2.60 degrees) compared to asymptomatic horses (FE-T17 = 3.07 degrees, FE-L1 = 3.12 degrees). CONCLUSIONS The objective measurement technique can detect differences between back kinematics in riding horses with signs of back dysfunction and asymptomatic horses. The clinical manifestation of back pain results in diminished flexion/extension movement at or near the thoracic lumbar junction. However, before applying the method more extensively in practice it is necessary to evaluate it further, including measurements of patients whose diagnoses can be confirmed and long-term follow-ups of back patients after treatment. POTENTIAL RELEVANCE Since the objective measurement technique can detect small movement differences in back kinematics, it should help to clinically describe and, importantly, objectively detect horses with back pain and dysfunction.

Relationship between scintigraphic and radiographic evaluations of spinous processes in the thoracolumbar spine in riding horses without clinical signs of back problems

REASONS FOR PERFORMING STUDY Radiography and scintigraphy are used to aid diagnosis of the cause of back pain, but a large variation in appearance and radiopharmaceutical uptake in fully functioning horses make diagnosis difficult. OBJECTIVES To describe the range of and compare scintigraphic and radiographic findings in the spinous processes of horses without clinical signs of back problems. METHODS Thirty-three apparently normal riding horses underwent scintigraphic and radiographic examinations of the spinous processes in the thoracolumbar spine. Scintigraphic images were evaluated in a continuous blue, green and red colour scale, and the level of radiopharmaceutical uptake in the spinous processes from T10-L2 was graded into none, mild, moderate or severe increased radiopharmaceutical uptake. Structural changes along the borders of the spinous processes and the width of the interspinous spaces from T10-L2 were recorded. RESULTS Only 7 horses had no scintigraphic or radiographic findings. Nine horses had no increased radiopharmaceutical uptake, 17 had no sclerosis, 21 had no radiolucencies and 11 had normal spacing of the spinous processes (>4 mm wide). The majority of findings in 26 horses were located from T13-18 and were mild. CONCLUSIONS The findings of a wide spectrum of scintigraphic and radiographic changes leads to the conclusion that changes within this range found in affected horses cannot be interpreted as clinically significant. POTENTIAL RELEVANCE To determine whether scintigraphy and/or radiography can be used to separate horses with back pain from horses without clinical signs, the results from this study should be compared to the scintigraphic and radiographic findings in horses with clinical signs.

Kinematic evaluation of the back in fully functioning riding horses

REASONS FOR PERFORMING STUDY Clinical history and examination are important features in diagnosis of equine back dysfunction. However, interpretation is subjective and therefore may vary substantially. OBJECTIVES To establish a clinical tool to objectively evaluate the function of the equine back, in the form of a database on the kinematics of the back at the walk and trot in fully functioning riding horses. METHODS Thirty-three fully functioning riding horses walked and trotted on a treadmill. Morphometrics and kinematics were tested for correlations to age, height, weight and stride length, and differences between gender (geldings and mares) and use (dressage and showjumping). RESULTS A database for range of movement and symmetry of movement for extension and flexion, lateral bending, lateral excursion and axial rotation was presented. Symmetry values were very high for all variables. Significant differences were observed in use and gender. Age was negatively correlated to extension and flexion of the thoracolumbar junction. CONCLUSIONS Interrelationships between use, gender and age to conformation and movement were established. POTENTIAL RELEVANCE The database provides a basis for objective reference for diagnosis, therapy and rehabilitation of clinical cases of back dysfunction.

Risk factors associated with hindlimb lameness and degenerative joint disease in the distal tarsus of Icelandic horses.

The aim of this study was to evaluate potential risk factors associated with hindlimb lameness and radiographic signs of degenerative joint disease (DJD) in the distal tarsus in Icelandic horses. The material consisted of riding horses (n = 420) age 6-12 years sired by 17 selected sires representing all major breeding lines, and of riding horses (n = 194) in the same age range sired by other sires. The examination protocol included the following: interview with owners/trainers, assessment of conformation, motion evaluation and radiographic examination. At the interview, data related to factors outside the horse (environmental variables) and data associated directly with the horse (intrinsic variables) were obtained. Data analysis was performed in 2 steps: screening using bivariate analysis, followed by testing with a multivariate logistic regression model. In the multivariate analysis, the factors of sire, age when broken to saddle and stud show participation were strongly associated with the prevalence of lameness. Height at the croup and ability to perform different gaits were also associated with the prevalence of lameness, but to a lesser degree. The risk factors of age, tarsal angle and birthplace were significantly associated with radiographic signs of DJD in the distal tarsus. Neither the variation in applied training intensity, the use of a professional or amateur trainer nor the temperament or front limb action of the individual horse was significantly associated with the prevalence of hindlimb lameness and/or radiographic signs of DJD in the distal tarsus in the Icelandic horse.

Radiographic and clinical survey of degenerative joint disease in the distal tarsal joints in Icelandic horses

The prevalence of degenerative joint disease (DJD) in the distal tarsal joints and the relation between radiographic and clinical signs compatible with the disease were estimated in a population of Icelandic horses used for riding. The material consisted of 614 horses age 6-12 years (mean age = 7.9 years). Radiographs with 3 projections of each tarsus were made and a clinical examination, including palpation of the medial aspect of the distal tarsus and motion evaluation of the hindlimbs before and after a flexion test of the tarsus, was performed. Radiographic signs of DJD in the distal tarsal joints were found in 30.3% of the horses and the prevalence was strongly correlated with age. Hindlimb lameness before and after flexion test and palpation abnormalities were significantly associated with the radiographic findings. The lameness was usually mild and, in most cases, detectable only after the flexion test. The prevalence of lameness was not significantly correlated with age. Lameness could not be predicted by details of the radiographic findings.

Effect of local analgesia on movement of the equine back.

REASONS FOR PERFORMING STUDY Diagnostic infiltration of local anaesthetic solution is commonly used in cases of equine back pain. Evaluation is subjective and it is not known how local analgesia of the back affects horses without clinical signs of back pain. OBJECTIVES To evaluate the effect of infiltration of local anaesthetics on the movement of the back in horses without clinical signs of back pain, and to evaluate the usefulness of kinematic studies as an objective and quantitative tool in evaluating local analgesia in clinical practice. METHODS The kinematics of the back in 10 clinically sound horses were measured on 2 occasions at walk and trot before and after injections with mepivacaine and sodium chloride around the interspinous spaces between T16 and L2. The kinematics were compared between the 2 occasions before injections and before and after each injection. RESULTS The range of motion (ROM) for dorsoventral flexion-extension (FE) of the back was increased significantly in all measured segments other than T10 at walk, as was lateral bending (LB) at T10, L3 and L5 after injection of mepivacaine. For lateral excursion (LE), total movement increased at all measured segments. At trot the only affected segment was L3, where the injection with mepivacaine decreased the ROM for FE. After injection of sodium chloride the ROM for FE increased at T13 and T17 at walk. Lateral bending and LE were not affected at walk. At trot, LB increased at L3 and L5. CONCLUSIONS AND POTENTIAL RELEVANCE Diagnostic infiltration of local anaesthetic solution affects the function of the back in clinically sound horses, which must be considered when interpreting the use of this clinical aid in assessing clinical cases of back dysfunction. Kinematics can qualitatively and quantitatively evaluate the effect of local analgesia of the back.

The heritability of degenerative joint disease in the distal tarsal joints in Icelandic horses

The heritability of radiographic signs of degenerative joint disease (DJD) in the distal tarsal joints and hind limb lameness after flexion test of the tarsus was estimated in a population of Icelandic horses being used for riding. Furthermore, the genetic and phenotypic correlation between the radiographic signs and lameness was estimated. Of the 614 examined horses, aged 6–12 years, 420 belonged to progeny groups from 17 selected stallions and 194 were sired by unselected stallions. The heritability was analyzed by two statistical models based on the threshold liability concept, a non-linear sire model and a linear animal model. The heritability of radiographic signs of DJD in the distal tarsal joints was not found to be significantly different from zero. The h2 estimate for lameness was higher and in the order of 0.4. A positive genetic and phenotypic correlation was identified between radiographic signs of DJD in the distal tarsal joints and lameness. The results indicate that the prevalence of DJD in the distal tarsal joints could be reduced in Icelandic riding horses by breeding selection based on flexion test of the tarsus followed by radiographic examination.

High detail radiography and histology of the centrodistal tarsal joint of Icelandic horses age 6 months to 6 years.

REASONS FOR PERFORMING STUDY Osteoarthrosis (OA) in the distal tarsal joints, bone spavin, is a well known condition which is common in Icelandic horses age 6-12 years. OBJECTIVES To determine the nature, location and age of appearance of early radiographic and histological changes in the centrodistal tarsal joint (CD) of young Icelandic horses. METHODS Slab sections from the CD of young Icelandic horses were examined by high detail radiography (age 6 months to 6 years, n = 111) and histology (age 6 months to 4 years, n = 82) to detect and describe the early changes indicative of OA. Horses younger than 5 years were unridden. RESULTS Chondronecrotic lesions histologically similar to those described in the early pathogenesis of OA were seen in 33% of the joints, located both medially and laterally. Radiographic sclerosis of the subchondral bone was recorded in 60% of the specimens, most often medially. Medial location was not associated with chondronecrosis, but was strongly related to age. Sclerosis was an infrequent finding on the lateral side, and was probably secondary to chondronecrosis in the corresponding part of the joint. Small defects in the subchondral bone were considered to be the most specific radiographic sign of OA as they were strongly associated with chondronecrosis. CONCLUSIONS The high prevalence of chondronecrosis in the young horses indicates an early onset and slow progression of the disease. The early appearance also shows that the initiation of the disease is unrelated to the use of horses for riding. As clinical manifestation of OA in the distal tarsal joints is most often described in mature or old horses, the first stages of the disease are not likely to result in clinical signs. Subchondral bone sclerosis did not appear to be a primary factor in the development of OA in the CD but was considered to reflect an uneven distribution of biomechanical forces within the joint. POTENTIAL RELEVANCE The development of OA in the CD of young Icelandic horses seems to be due to poor conformation or joint architecture rather than trauma or overloading. These aetiological factors are likely to be of importance for OA in the distal tarsal joints in other breeds as well. The influence of hindlimb conformation and the architecture of the distal tarsal joints on the biomechanics of joints need to be investigated, preferably by locomotion analysis in young horses.