Radiographic and scintigraphic evaluation of spondylosis in the equine thoracolumbar spine: A retrospective study

Reasons for performing study: Clinical, radiographic and scintigraphic signs associated with spondylosis of the equine thoracolumbar spine have been poorly documented. Objectives: To establish an objective radiographic and scintigraphic grading system for spondylosis lesions; to estimate the prevalence of spondylosis in a population of horses with back pain; and to compare the results of radiography and scintigraphy Methods: Radiographic images of the thoracolumbar spine from 670 horses with clinical signs of back pain were graded. Scintigraphic images from horses with spondylosis lesions underwent subjective and objective analysis. Sensitivity and specificity of scintigraphy for detection of spondylosis relative to radiography for identification of spondylosis were calculated, and Chi‐squared analysis was performed to test for an association between location and severity of lesions. Results: Twenty‐three of 670 horses (3.4%) with back pain had radiographic evidence of spondylosis. Of these horses, 14 (61%) had more than one lesion and 44% (n = 22) of lesions occurred between T11‐T13 vertebral bodies. Only 33% (n = 28) of locations with radiographic changes had increased radiopharmaceutical uptake. Conclusion: Spondylosis occurs at a low prevalence in horses with back pain. It may be present alone or in association with other osseous abnormalities. The clinical significance of spondylosis needs further investigation. Potential relevance: Spondylosis is uncommon but may be a contributor to back pain in the horse.     

Nuclear scintigraphic assessment of the thoracolumbar synovial intervertebral articulations

Reasons for performing study: The results of nuclear scintigraphic examination of the thoracolumbar synovial intervertebral articulations (facet joints) have to date been poorly documented. Objectives: To establish an objective scintigraphic grading system for the facet joints; to investigate the relationship between the presence or absence of clinical signs of back pain and increased radiopharmaceutical uptake (IRU); and to compare the results of scintigraphy and radiography. Methods: Nuclear scintigraphic images of the 13th thoracic (T13) to first lumbar (L1) vertebrae were graded subjectively (visual assessment of the image) and objectively (using region of interest analysis) from 31 clinically normal horses in full work (Group N) and 65 horses with clinical evidence of thoracolumbar region pain and osteoarthritis of ≥1 facet joint (Group B). Sensitivity and specificity of IRU for detection of back pain and radiographic abnormalities were assessed. A Spearman correlation was performed to test for an association between the grade of IRU and the classification of radiographic abnormality. Results: The objective scintigraphic grades were matched by 96.7% of subjective grades. IRU was seen more commonly in Group B (61.5%) than in Group N (25.8%), and moderate or intense IRU was only seen in Group B. The strongest association between radiographic abnormalities and scintigraphy was seen in horses with intense IRU. Conclusions: Moderate or intense IRU in a facet joint is more likely to be seen in horses with back pain than in clinically normal horses. Potential relevance: Nuclear scintigraphy is a potentially useful tool in the evaluation of a horse with thoracolumbar region pain.     

Semi‐quantitative methods yield greater inter‐ and intraobserver agreement than subjective methods for interpreting 99mtechnetium‐hydroxymethylene‐diphosphonate uptake in equine thoracic processi spinosi

Scintigraphy is a standard diagnostic method for evaluating horses with back pain due to suspected thoracic processus spinosus pathology. Lesion detection is based on subjective or semi‐quantitative assessments of increased uptake. This retrospective, analytical study is aimed to compare semi‐quantitative and subjective methods in the evaluation of scintigraphic images of the processi spinosi in the equine thoracic spine. Scintigraphic images of 20 Warmblood horses, presented for assessment of orthopedic conditions between 2014 and 2016, were included in the study. Randomized, blinded image evaluation was performed by 11 veterinarians using subjective and semi‐quantitative methods. Subjective grading was performed for the analysis of red‐green‐blue and grayscale scintigraphic images, which were presented in full‐size or as masked images. For the semi‐quantitative assessment, observers placed regions of interest over each processus spinosus. The uptake ratio of each processus spinosus in comparison to a reference region of interest was determined. Subsequently, a modified semi‐quantitative calculation was developed whereby only the highest counts‐per‐pixel for a specified number of pixels was processed. Inter‐ and intraobserver agreement was calculated using intraclass correlation coefficients. Inter‐ and intraobserver intraclass correlation coefficients were 41.65% and 71.39%, respectively, for the subjective image assessment. Additionally, a correlation between intraobserver agreement, experience, and grayscale images was identified. The inter‐ and intraobserver agreement was significantly increased when using semi‐quantitative analysis (97.35% and 98.36%, respectively) or the modified semi‐quantitative calculation (98.61% and 98.82%, respectively). The proposed modified semi‐quantitative technique showed a higher inter‐ and intraobserver agreement when compared to other methods, which makes it a useful tool for the analysis of scintigraphic images. The association of the findings from this study with clinical and radiological examinations requires further investigation.     

Close, impinging and overriding spinous processes in the thoracolumbar spine: the relationship between radiological and scintigraphic findings and clinical signs

Reasons for performing study: There has been no objective study comparing radiological features of spinous processes (SPs) in the thoracolumbar region and/or scintigraphic findings with clinical signs. Objectives: To investigate the relationship between the presence or absence of clinical signs of back pain and: 1) radiological findings of close, impinging or overriding SPs; 2) increased radiopharmaceutical uptake (IRU) in the SPs; and 3) the combination of radiological findings and IRU. Also to determine the prevalence of concurrent osseous pathology. Methods: Five‐hundred and eighty‐two horses, presented for perceived back pain and poor performance, underwent comprehensive clinical investigation including diagnostic analgesia of the forelimbs, hindlimbs, back and sacroiliac joints, and radiographic and scintigraphic evaluation of the thoracolumbar spine. Radiological and scintigraphic grades were determined subjectively. Statistical analysis was performed to determine the relationships between clinical signs of back pain, radiological and scintigraphic features, age, breed, gender, discipline, height and weight. Results: Thoroughbreds (TBs) were over‐represented with thoracolumbar pain compared with Warmbloods and TB cross breeds. There was a significant association between maximum and total radiological grades of the SPs and thoracolumbar pain, between maximum and total grades of IRU and thoracolumbar pain, and between a combination of radiological and scintigraphic abnormalities and thoracolumbar pain. Horses with osteoarthritis (OA) of the synovial intervertebral articulations (SIAs) were more likely to have thoracolumbar pain than horses with lesions of the SPs alone, but the presence of OA of the SIAs and lesions of the SPs was associated with the highest likelihood of thoracolumbar pain. Conclusions and potential relevance: Fore‐ or hindlimb lameness and/or pain associated with the sacroiliac joints could mimic primary thoracolumbar pain. A combination of radiology and scintigraphy gives the most accurate prediction of thoracolumbar pain, but diagnostic analgesia is crucial for accurate diagnosis.     

EFFECTS OF X‐RAY BEAM ANGLE AND GEOMETRIC DISTORTION ON WIDTH OF EQUINE THORACOLUMBAR INTERSPINOUS SPACES USING RADIOGRAPHY AND COMPUTED TOMOGRAPHY—A CADAVERIC STUDY

The widths of spaces between the thoracolumbar processi spinosi (interspinous spaces) are frequently assessed using radiography in sports horses; however effects of varying X‐ray beam angles and geometric distortion have not been previously described. The aim of this prospective, observational study was to determine whether X‐ray beam angle has an effect on apparent widths of interspinous spaces. Thoracolumbar spine specimens were collected from six equine cadavers and left‐right lateral radiographs and sagittal and dorsal reconstructed computed tomographic (CT) images were acquired. Sequential radiographs were acquired with each interspinous space in focus. Measurements were performed for each interspinous space in the focus position and up to eight angled positions as the interspinous space moved away from focus (±). Focus position measurements were compared to matching sagittal CT measurements. Effect of geometric distortion was evaluated by comparing the interspinous space in radiographs with sagittal and dorsal reconstructed CT images. A total of 49 interspinous spaces were sampled, yielding 274 measurements. X‐ray beam angle significantly affected measured width of interspinous spaces in position +3 (P = 0.038). Changes in width did not follow a consistent pattern. Interspinous space widths in focus position were significantly smaller in radiographs compared to matching reconstructed CT images for backs diagnosed with kissing spine syndrome (P < 0.001). Geometric distortion markedly affected appearance of interspinous space width between planes. In conclusion, X‐ray beam angle and geometric distortion influence radiographically measured widths of interspinous spaces in the equine thoracolumbar spine, and this should be taken into consideration when evaluating sport horses.     

COMPARISON OF RADIOGRAPHIC AND SCINTIGRAPHIC FINDINGS OF THE SPINOUS PROCESSES IN THE EQUINE THORACOLUMBAR REGION

Back pain is common in horses, but there has been no large‐scale in‐depth study describing radiographic changes of the spinous processes, the relationship between radiographic and scintigraphic findings, and the effect of size, age, breed, or discipline. The objectives were to investigate the frequency of occurrence in horses with perceived back pain of: (1) radiographic alteration of the spinous process structure; (2) increased radiopharmaceutical uptake (IRU) in the spinous processes; and (3) to compare radiographic and scintigraphic findings; and to determine if there was breed, gender, age, bodyweight, height, or work discipline predisposition for close, impinging, or overriding spinous processes. Radiographic and scintigraphic images of the thoracolumbar spine of 604 horses were graded. A radiographic grade for each spinous process (T8–L6) was assigned (0–7). The maximum radiographic grade for each horse was defined as the highest grade assigned to any spinous process; the total radiographic grade was the sum of all grades for each horse. A scintigraphic grade for each spinous process was determined (0–3). The maximum scintigraphic grade for each horse was defined as the highest grade assigned to any spinous process; the total scintigraphic grade was the sum of all grades for each horse. Associations between radiology and scintigraphy and age, gender, breed, height, weight, and discipline were analyzed statistically. The severity of radiographic lesions of the spinous processes was associated with the severity of scintigraphic abnormalities. The caudal thoracic spine (T14–T17) was most frequently affected. There was a significant breed and age effect, with Thoroughbreds and older horses having higher total and maximum radiographic grades. The severity of the lesions of the spinous processes was significantly associated with the presence of osteoarthritis of the articular process joints. It was concluded that there is a wide range of radiographic abnormalities of the spinous processes seen in horses with or without back pain. There is an association between radiographic and scintigraphic grades of the spinous processes.     

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.     

Structure and Innervation of the Equine Supraspinous and Interspinous Ligaments

Pain related to the osseous thoracolumbar spine is common in the equine athlete, with minimal information available regarding soft tissue pathology. The aims of this study were to describe the anatomy of the equine SSL and ISL (supraspinous and interspinous ligaments) in detail and to assess the innervation of the ligaments and their myofascial attachments including the thoracolumbar fascia. Ten equine thoracolumbar spines (T15‐L1) were dissected to define structure and anatomy of the SSL, ISL and adjacent myofascial attachments. Morphological evaluation included histology, electron microscopy and immunohistochemistry (S100 and Substance P) of the SSL, ISL, adjacent fascial attachments, connective tissue and musculature. The anatomical study demonstrated that the SSL and ISL tissues merge with the adjacent myofascia. The ISL has a crossing fibre arrangement consisting of four ligamentous layers with adipose tissue axially. A high proportion of single nerve fibres were detected in the SSL (mean = 2.08 fibres/mm²) and ISL (mean = 0.75 fibres/mm²), with the larger nerves located between the ligamentous and muscular tissue. The oblique crossing arrangement of the fibres of the ISL likely functions to resist distractive and rotational forces, therefore stabilizing the equine thoracolumbar spine. The dense sensory innervation within the SSL and ISL could explain the severe pain experienced by some horses with impinging dorsal spinous processes. Documentation of the nervous supply of the soft tissues associated with the dorsal spinous processes is a key step towards improving our understanding of equine back pain.     

Enthesophytosis and Impingement of the Dorsal Spinous Processes in the Equine Thoracolumbar Spine

Impingement of the dorsal spinous processes (DSPs) is a common cause of pain and poor performance in sport horses, but there is limited information regarding regional differences in the prevalence and severity of DSP osseous lesions in the equine thoracolumbar spine. It was hypothesized that lesion severity would increase with horse age and height, and that severe lesions would be more prevalent in the mid-caudal thoracic region. The thoracolumbar spines of 33 horses were removed postmortem, disarticulated, and boiled out. The thoracic and lumbar DSPs were examined for the presence of proliferative or lytic osseous lesions of the DSPs. Age and height of the horses were recorded, and severity of pathologic changes at each vertebral level was scored using an ordinal grading system (grades 0–3) and a continuous visual analog scale (VAS). Osseous lesions of the DSPs were present at every vertebral level from C7–T1 to L6–S1, and 70% of horses had at least one lesion of severity grade 2 or higher. Grade 3 lesions were found in the cranial thoracic (T2–T4), mid-thoracic to cranial lumbar (T11–L1) and mid-lumbar (L4–L5) segments. Analysis of VAS data using analysis of variance indicated that increasing age and height were associated with more severe osseous lesions (P < .001). DSP osseous lesions occur frequently in horses with more severe lesions in the cranial thoracic, mid to caudal thoracic, and mid-lumbar regions. Lesions in the cranial thoracic and lumbar regions present a challenge for diagnostic imaging and may be underdiagnosed clinically.     

Cervical disc width index is a reliable parameter and consistent in young growing Dutch Warmblood horses

Intervertebral disc disease, as well as the associated alteration of the radiographic intervertebral disc space width, has been reported in horses. Disc height index (DHI) has proven to be an accurate and objective parameter in other species but data related to this parameter are lacking in horses. Therefore, the aims of this retrospective longitudinal diagnostic accuracy study were (a) to evaluate the reliability of measurements within and between observers of the equine Disc Width Index (EDWI) as a parameter for radiographic equine cervical intervertebral disc space width, and (b) to evaluate the sequential development of the EDWI over time. For this, EDWI from all intervertebral disc spaces between second cervical (C) to first thoracic (Th) vertebrae were obtained in a group of 39 Dutch Warmblood horses at 1, 5, and 18 months of age, by one European College of Veterinary Diagnostic Imaging (ECVDI) board‐certified veterinary radiologist (S.V.) and two veterinary students. Bland‐Altmann plots and intraclass Correlation Coefficient revealed a good intra‐ and interobserver agreement. A linear mixed‐effect model did reveal that mean EDWI increases significantly toward the caudal cervical spine, but did not differ significantly for a certain location over time or between sexes. Spearman's rank test did show a significant correlation between the vertebral alignment angle induced by different head‐neck positions and a normalized EDWI (ρ = 0.33, P < .0001). Student's t‐test revealed that the presence of C6‐C7 transposition of the transverse processes did not influence EDWI significantly. It was concluded that EDWI represents a reliable parameter for equine cervical radiographic intervertebral disc space width. Practical implementation of EDWI warrants monitoring in a group of adult horses while maintaining a standardized head‐neck position.     

SCINTIGRAPHIC AND RADIOGRAPHIC APPEARANCE OF THE SACROILIAC REGION IN HORSES WITH GAIT ABNORMALITIES OR POOR PERFORMANCE

Nuclear bone scintigraphy is commonly used in the diagnosis of sacroiliac disease in horses. The aim of the present retrospective study was to determine if there was an association between radiopharmaceutical uptake pattern and radiographic appearance of the sacroiliac region in horses. Seventy-nine horses undergoing bone scintigraphy with Tc-99 m-HDP and radiography of the pelvis because of lameness or poor performance were studied. Subjective and semiquantitative methods were used to characterize and compare radiopharmaceutical uptake between horses. Ventrodorsal radiographs of the region were obtained and were evaluated. Subjectively, 70 horses (88.6%) had an abnormal uptake pattern. In nine horses, the sacroiliac region was normal (11.4%). There was no association between subjective evaluation of the scintigraphic images and semiquantitative methods. There was a significant association between radiopharmaceutical uptake and conformation (T- or Y-like form) and shape (butterfly-, wing-, leaf-, or horn-like) of the sacrum. The radiopharmaceutical uptake of the tubera sacralia was significantly higher in males (left side P =0.002, right side P =0.003). In conclusion, the conformation of the sacrum may play an important role in the scintigraphic appearance and may be the cause of increased radiopharmaceutical uptake.     

Implications of the neuroanatomy of the equine thoracolumbar vertebral column with regional anaesthesia and complications following desmotomy of the interspinous ligament

Impinging/overriding dorsal spinous processes (DSPs) of the thoracolumbar vertebrae are a common cause of poor performance in horses. In the last five decades, numerous surgical treatments have been reported on, from transverse transection of the affected DSPs, and endoscopic resection of the affected DSPs, to transection of the interspinous ligament. Until recently, cosmetic outcomes have been reported as good to excellent in studies. However, a previously unreported complication of neurogenic atrophy of the contralateral epaxial muscle following desmotomy of the interspinous ligament has been recently reported. The authors hypothesised that this was because of a more lateral approach than previously described, resulting in the scissors being too far across midline and transecting a nerve in the region. Considering this finding, we have reviewed the literature on the neuroanatomy of the thoracolumbar region in the horse. Literature on the neuroanatomy of the horse is lacking when compared with that of humans and companion animals, with most of the work extrapolated from companion animals. Based on the current literature, we hypothesise that transection of an intermediate branch of the dorsal spinal nerve supplying the m. longissimus is potentially the cause of the post-operative neurogenic atrophy. The lack of detailed knowledge of the neural anatomy of the equine back has resulted in the role of local anaesthesia in localising pain in the equine back being poorly understood. The wide variation in techniques used for localising back pain may explain why some horses suffering from poor performance or an abnormal gait because of back pain improve to local anaesthesia of the back while others do not. This review article highlights a lack of anatomical knowledge regarding the equine thoracolumbar region in the literature despite diagnostic local anaesthesia, medication, and surgery in this area being relatively common.     

Relationship between intervertebral joint morphology and mobility in the equine thoracolumbar spine

The anatomical features of 21 equine thoracolumbar spines, obtained from horses with clinically normal backs, were examined and the results compared with recent data on the mobility of the joint complexes of the horse's spine. The thoracolumbar spine can be divided into four regions based upon the morphology of the joint complexes: the first thoracic intervertebral joint (T1-2), the cranial and mid thoracic region (T2-T16), the caudal thoracic and lumbar region (T16-L6) and the lumbosacral joint. The mobility of the intervertebral joints in each of these regions can be related to their morphology, particularly the shape, size and orientation of the articular facets and the presence and frequent fusion of the lateral joints of the lumbar spine. The shape and thickness of the intervertebral discs also appear to be of importance.     

Dynamic mobilisation exercises increase cross sectional area of musculus multifidus

Reason for performing study: In human subjects with back pain, the deep spinal stabiliser m. multifidus is inhibited ipsilaterally leading to atrophy, asymmetry and intervertebral instability. Specific physiotherapeutic exercises are required to reactivate m. multifidus. This study assesses the effect of dynamic mobilisation exercises on size and symmetry of m. multifidus in the equine caudal thoracic and lumbar spine. Hypotheses: Regular performance of dynamic mobilisation exercises over a period of 3 months increases cross sectional area (CSA) and left‐right symmetry of m. multifidus muscles in the caudal thoracic and lumbar spine. Methods: Eight horses performed dynamic mobilisation exercises (3 cervical flexions, one cervical extension and 3 lateral bending exercises to the left and right sides) with 5 repetitions/exercise/day on 5 days/week for 3 months during which time they were not ridden. Left and right m. multifidus CSA was measured ultrasonographically at 6 levels from T10 to L5 at the start (initial evaluation) and end (final evaluation) of the 3 month study. Changes in CSA of the right and left m. multifidus muscles and symmetry of m. multifidus CSA on the right and left sides between the 2 evaluations were sought using analysis of variance (P<0.05). Results: Between the initial evaluation and final evaluation m. multifidus CSA increased significantly at all 6 spinal levels on both right and left sides. Asymmetries in m. multifidus CSA between the right and left sides decreased between the initial and final evaluations. Conclusions: Hypertrophy of multifidus occurred over a 3 month period during which dynamic mobilisation exercises were the only exercise performed. Potential relevance: Dynamic mobilisation exercises maybe a useful rehabilitative technique for horses in which m. multifidus has atrophied in response to back pain.     

Scintigraphic examination of the cartilages of the foot

REASONS FOR PERFORMING STUDY: Radiographic examination of the cartilages of the foot is well documented; however, there is limited information about their scintigraphic assessment. OBJECTIVES: To evaluate the scintigraphic appearance of the cartilages of the foot using subjective and quantitative image analysis and to correlate radiographic and scintigraphic findings. HYPOTHESES: An ossified cartilage would have similar radiopharmaceutical uptake (RU) to the ipsilateral aspect of the distal phalanx; RU would extend throughout the length of the ossified cartilage; a separate centre of ossification (SCO) would be identified on a scintigraphic image; and fracture or trauma to an ossified cartilage would manifest as increased RU (IRU). METHODS: Front feet (n = 223) of horses (n = 186) that had dorsopalmar radiographic views and dorsal scintigraphic images were included in the study. The cartilages of the foot were graded radiographically and scintigraphically. Quantitative evaluation of the scintigraphic images was carried out using region of interest (ROI) analysis. For statistical analysis RU ratios were used. Correlations between a radiographically detected SCO and focal RU and between IRU and radiographic abnormalities were assessed. RESULTS: There was a good correlation and an excellent agreement between radiographic and scintigraphic grades. ROI analysis showed a proximal to distal increase in RU ratios within each cartilage of the foot. A radiographically identified SCO could be detected scintigraphically in 12/17 feet (70.6%). Thirty-eight feet had IRU in the region of a cartilage, 25 of which (65.8%) had corresponding radiographic abnormalities. Fracture of an ossified cartilage was associated with IRU in all horses. CONCLUSIONS AND POTENTIAL RELEVANCE: Scintigraphy may give information about the potential clinical significance of ossification of the cartilages of the foot and associated lesions, therefore prompting further investigation by use of a uniaxial ipsilateral palmar nerve block and imaging, using either magnetic resonance imaging and/or computed tomography.     

Functional Electrical Stimulation (FES) and the Effect on Equine Multifidi Asymmetry

Asymmetry of the multifidi has been correlated with scoliosis and back pain in humans and has been investigated as a factor in equine back pain as well. The purpose of this study was to determine if FES would affect the symmetry of equine thoracolumbar multifidi when compared to controls. Twelve horses received 24 FES treatments bilaterally over the thoracolumbar region for 8 weeks. Twelve additional control horses received no FES treatments. Ultrasonographic measurements of the cross-sectional area (CSA) of the multifidi of the treatment horses at seven thoracolumbar levels were compared to determine the change in left and right asymmetry post-FES. The same measurements during the same period were also taken in the control group. All measurements were blinded for evaluation. Statistical significance was assessed utilizing two-sided, matched-pairs t-tests, and Welch’s (unequal variances) t-test (alpha = 0.05). Multiple comparisons were accounted for using the Sidak correction. A significant improvement in multifidi asymmetry was observed, post-FES, at all seven thoracolumbar levels, with no evidence of asymmetry improvement in the control group. The difference between mean improvements of the treatment and control groups was statistically significant (P < .001). FES significantly improved the symmetry of equine multifidi, and evidence was provided for the effectiveness of FES at each of seven thoracolumbar levels. The improvement in symmetry appeared to result from increases, decreases, and maintenance of the CSA of the left and right multifidi in various combinations. The FES protocol used in this study has the potential to improve spinal function and assist in reducing back pain in horses.     

CLINICAL RELEVANCE OF ABNORMAL SCINTIGRAPHIC FINDINGS OF ADULT EQUINE RIBS

Horses with cranial rib abnormalities may exhibit severe acute lameness and may have unusual gait deficits characterized by forelimb abduction during protraction at the walk. Horses with caudal rib abnormalities may resent being saddled and ridden. In a retrospective evaluation of 20 horses with a documented rib lesion, 25 sites of increased radiopharmaceutical uptake were found in one or more ribs. Thirteen (52%) scintigraphic lesions involved the first rib; four were located immediately dorsal to the sternal articulation, eight were near the costochondral junction and one was at the costovertebral junction. Six (24%) scintigraphic rib lesions involved ribs 2–8; one was located immediately dorsal to the sternal articulation, three were at the costovertebral junction and two were near the costochondral junction. Six (24%) scintigraphic rib lesions involved the mid‐portion (five) or costovertebral junction (one) of ribs 9–18. The 20 horses were divided into three groups based on the clinical relevance of the scintigraphic findings. Group 1 (n=3) horses had clinical signs attributed to a rib abnormality; Group 2 (n=6) horses had a rib abnormality that was a plausible explanation for clinical signs; Group 3 (n=11) horses had clinical signs that could not be attributed to a rib abnormality. For horses with cranial rib abnormalities, a modified lateral scintigraphic image with the ipsilateral limb pulled caudally and a left (right) 45° caudal–right (left) radiograph facilitated the diagnosis.     

Relationship between spinal biomechanics and pathological changes in the equine thoracolumbar spine

The relationship between spinal biomechanics and pathological changes occurring in functionally normal equine thoracolumbar spines was studied in 23 horses. Ventrolateral vertebral body osteophytes occurred in 36 per cent of the spines. The majority occurred between the 10th and 17th thoracic vertebrae with the largest being found between the 11th and 13th thoracic vertebrae, the region of the thoracic spine where the greatest amount of lateral bending and axial rotation occurs. Impingement of the dorsal spinous processes was detected in 86 per cent of the spines with most lesions occurring between the 13th and 18th thoracic vertebrae. The severity of occurrence of impingement did not appear to be related to regional spinal mobility. Degeneration of intervertebral discs was observed in three of four specimens that were sectioned sagittally. It occurred in the first thoracic and the lumbosacral intervertebral discs and appeared to be related to the increased dorsoventral mobility and the increased disc thickness of these joints. The characteristic distribution of fractures of the thoracolumbar spine is discussed with respect to the biomechanics of the spine.     

Clinical assessment and grading of back pain in horses

BackgroundThe clinical presentation of horses with back pain (BP) vary considerably with most horse''s willingness to take part in athletic or riding purpose becoming impossible. However, there are some clinical features that are directly responsible for the loss or failure of performance.ObjectivesTo investigate the clinical features of the thoracolumbar region associated with BP in horses and to use some of the clinical features to classify equine BP.MethodsTwenty-four horses comprised of 14 with BP and 10 apparently healthy horses were assessed for clinical abnormality that best differentiate BP from normal horses. The horses were then graded (0–5) using the degree of pain response, muscular hypertonicity, thoracolumbar joint stiffness and overall physical dysfunction of the horse.ResultsThe common clinical features that significantly differentiate horses with BP from non-BP were longissimus dorsi spasm at palpation (78.6%), paravertebral muscle stiffness (64.3%), resist lateral bending (64.3%), and poor hindlimb impulsion (85.7%). There were significantly (p < 0.05) higher scores for pain response to palpation, muscular hypertonicity, thoracolumbar joint stiffness and physical dysfunction among horses with BP in relation to non-BP. A significant relationship exists between all the graded abnormalities. Based on the cumulative score, horses with BP were categorized into mild, mild-moderate, moderate and severe cases.ConclusionsBP in horse can be differentiated by severity of pain response to back palpation, back muscle hypertonicity, thoracolumbar joint stiffness, physical dysfunctions and their cumulative grading score is useful in the assessment and categorization of BP in horses.     

Efficacy of tiludronate in the treatment of horses with signs of pain associated with osteoarthritic lesions of the thoracolumbar vertebral column

OBJECTIVE: To evaluate the efficacy of tiludronate for the treatment of horses with signs of pain associated with lesions of the thoracolumbar vertebral column. ANIMALS: 29 horses with clinical manifestations of pain associated with lesions of the thoracolumbar vertebral column and abnormal radiographic findings indicative of osteoarthritis of the articular processes-synovial intervertebral joints. PROCEDURES: Horses were initially examined in accordance with a standardized protocol, which included radiographic, ultrasonographic, and scintigraphic examinations. Fifteen horses were randomly assigned to receive tiludronate (1 mg/kg, IV, as a slow-rate infusion), and 14 horses received a control substance (day 0). Horses were monitored for the subsequent 120 days. Clinical evaluations were performed on days 60 and 120. Horses that had no evidence of clinical improvement on day 60 were administered tiludronate. Statistical analyses were performed to compare efficacy at day 60, improvement of dorsal flexibility at day 120, and dorsal flexibility before and 60 days after administration of tiludronate. RESULTS: Horses treated with tiludronate had significant improvement in dorsal flexibility between days 0 and 60, compared with control horses. Clinical improvement in dorsal flexibility was still evident at day 120. The percentage of positive responses was higher in the tiludronate group at 60 days. CONCLUSIONS AND CLINICAL RELEVANCE: Tiludronate had efficacy in the treatment of horses with signs of pain induced by osteoarticular lesions of the thoracolumbar vertebral column, causing a significant improvement in dorsal flexibility. Tiludronate may offer a treatment option for the management of horses with intervertebral lesions and the associated pain.