Age and sex correlate with bony changes and anatomic variations of the lumbosacroiliac region of the vertebral column in a mixed population of horses

Osseous pathologic changes in the thoracic region of the equine vertebral column: A descriptive post-mortem study in three breeds

BACKGROUND

Data on equine thoracic pathology hardly exist in breeds other than Thoroughbreds.

OBJECTIVES

To describe pathological changes of the osseous thoracic vertebral column in Warmblood horses, Shetland ponies and Konik horses, and to compare prevalence and severity.

STUDY DESIGN

Descriptive post-mortem study.

METHODS

Computed tomography was used to examine the thoracic vertebral column of 34 Warmblood horses, 28 Shetland ponies, and 18 Konik horses. Osteoarthritis (OA), periarticular osteolysis, osseous cyst-like lesions and fragments of articular processes (APJs), costovertebral and costotransverse joints, soft tissue mineralisation surrounding these joints, intervertebral disc (IVD) mineralisation, impingement of spinous processes (SPs) and spondylosis were scored.

RESULTS

APJ aplasia (98%; 58/59) occurred in 14 Shetland ponies. OA predominated in Warmblood horses across all joints (45% vs. 29 and 32%, p < 0.001). OA and periarticular osteolysis were found in particular in the costotransverse joints (p < 0.001) across all breeds. Warmblood and Konik horses had more and severe soft tissue mineralisation than Shetland ponies (2.3%, score 1.5 and 3.2%, score 1.3, respectively, vs. 0.3%, score 0.9, p < 0.01). Mid location was most often affected with highest severity score (4.2%, 1.5, p < 0.001). Konik horses displayed the highest IVD mineralisation (20%, p < 0.001), which notably increased with age (p < 0.001) compared with Warmblood horses (4.5%) and Shetland ponies (1.1%). SPs impingement was absent in Shetland ponies, and most prevalent in Warmblood horses (11.2%, p < 0.001) compared with Konik horses (2.2%). Osseous cyst-like lesions, fragments and spondylosis were minimal in all breeds and nearly absent in Shetland ponies.

MAIN LIMITATIONS

Clinical histories and macroscopic and histologic examinations were unavailable.

CONCLUSIONS

Distinct breed differences exist in prevalence and severity of thoracic vertebral column osseous pathologies. Costotransverse joint pathology is more common than APJ pathology in all breeds. Warmblood horses are prone to OA, spondylosis and SPs impingement; Konik horses exhibit significant IVD mineralisation, and Shetland ponies demonstrate a high prevalence of APJ aplasia. Periarticular osteolysis, osseous cyst-like lesions, fragments and soft tissue mineralisation are notably low in Shetland ponies.

Computed tomography of the equine caudal spine and pelvis. Pathological findings in 56 clinical cases (2018-2023)

BACKGROUND

Computed tomography (CT) of the axial skeleton is increasing across many equine hospitals. CT of the pelvis and caudal spine in a large group of clinical cases has not been reported previously.

OBJECTIVE

To describe the pathological lesions identified in the caudal spine/pelvis in horses and ponies undergoing CT spine of this region.

STUDY DESIGN

A retrospective case series.

METHODS

Horses with CT imaging of the caudal spine/pelvis were included. Horses aged under 6 months and those with CT examinations performed post-mortem were excluded.

RESULTS

Fifty-six horses met the inclusion criteria. Ages ranged from 8 months to 20 years and bodyweights from 85 to 680 kg (mean 488 kg). Horses presented predominantly for lameness (30/56) and poor performance (18/56). Osseous pathology was identified in 41/56 horses; including osteoarthritis of the sacroiliac joint(s) (n: 28), pathology of the intervertebral disc joint(s) (n: 12), pelvic fractures (n: 9), osteoarthritis of the coxofemoral joint(s) (n: 8), ventral spondylosis (n: 6), acetabular rim fracture (n: 2), dislocation of coxofemoral joint(s) (n: 2), and dorsal dermal sinus of the sacrum (n: 1).

MAIN LIMITATIONS

The relationship between CT imaging findings and clinical signs in horses remains unclear. Further work is required to describe the relationship between congenital, developmental, and acquired changes in the caudal spine and pelvis, and clinical signs.

CONCLUSIONS

CT of the caudal spine and pelvis can be utilised in horses and ponies for diagnosing a range of clinical disorders that may be causing 'lumbosacroiliac pain', poor performance, hindlimb lameness, and stiffness. The pathologies we observed were diverse and many patients had multiple lesions.

Computed tomography of the equine caudal spine and pelvis: Technique, image quality and anatomical variation in 56 clinical cases (2018-2023)

BACKGROUND

Cross-sectional imaging improves the diagnostic accuracy of complex anatomical regions. Computed tomography (CT) of the pelvis and caudal spine in a large group of live horses and ponies has not been previously reported.

OBJECTIVE

To describe the procedure for acquiring CT images of horses' caudal spine/pelvis under general anaesthesia (GA) and to detail the image quality, artefacts and anatomical variations in this region.

STUDY DESIGN

Retrospective case series.

METHODS

Horses with CT of the caudal spine/pelvis were included. Horses under 6 months and CT examination performed post-mortem were excluded. Protocols, image quality, region of interest, anatomical features and morbidities were analysed.

RESULTS

Fifty-six horses (8 months to 20 years, 85-680 kg) met the inclusion criteria. GA ranged from 10 to 60 min (mean: 30, median: 32). There were no adverse events recorded in any of the horses associated with the procedure. Images of all horses were considered of diagnostic quality. Anatomical variations were common and included the location of diverging (widest) interspinous space, the presence of spina bifida in the lumbar and sacral spine, the shape of the last lumbar vertebra and the location of intertransverse joints in terms of where they were present and the degree of fusion/modelling.

MAIN LIMITATIONS

Not all horses underwent CT examination of the same regions, the upper size limit of horses is unknown and will vary depending on bore size and table infrastructure. Image noise, particularly in large horses and beam hardening artefacts from hardware and pelvis degraded image quality. Images were of insufficient quality in large horses for soft tissue interpretation.

CONCLUSION

CT of the caudal spine and pelvis in live horses with wide-bore CT machines and modified patient infrastructure was safe and produced diagnostic images.

Computed tomographic study analysing functional biomechanics in the thoracolumbar spine of horses with and without spinal pathology

To better understand physiological and pathological movement patterns in the equine thoracolumbar spine, investigation of the biomechanics on a segmental level requires a constant moment. A constant moment along the spinal column means that the same torque acts on each vertebral segment, allowing the range of motion of different segments to be compared. The aims of this study were to investigate the range of motion of the equine thoracolumbar spine in horses with and without spinal pathology and to examine whether the pressure between the spinous processes depends on the direction of the applied moment. Thoracolumbar spine specimens (T8-L4) of 23 horses were mounted in a custom-made mechanical test rig to investigate spinal biomechanics during lateral bending, axial rotation, flexion and extension using computed tomographic imaging. Results were compared between horses with spondylosis, overriding spinous processes and specimens free of gross pathology. The interspinous space pressure was additionally determined using a foil sensor. The median lateral bending between T9 and L3 was 3.7°-4.1° (IQR 5.4°-8.0°). Maximum rotational movement with inconsistent coupled motion was observed at T9-T16 (p < 0.05). The dorsoventral range of motion was greatest in segments T9-T11 (p < 0.05). Spondylosis and overriding spinous processes restricted spinal mobility, depending on the severity of the condition. There was no significant difference in interspinous pressure during motion (p = 0.54). The biomechanical study confirmed that the range of motion of intervertebral joints depends on the anatomical position of the joint and the direction of the moment applied. Restricted mobility was evident in the presence of different grades of overriding spinous processes or spondylosis. A better understanding of equine spinal biomechanics in horses with spinal pathology facilitates individual rehabilitation.