There is a lack of understanding of the pathological and/or physiological nature of lumbosacral region pain. This descriptive post-mortem case series aimed to describe the gross variations of osseous and soft tissues, and histopathological features of nerve tissue in the lumbosacral region of affected and control horses.
The published article was titled, “Gross post-mortem and histological features in 27 horses with confirmed lumbosacral region pain and five control horses: A descriptive cadaveric study” and was authored by Quiney, L.; Stewar, J.; Routh, J.; and Dyson, S.
All horses subjected to euthanasia for which a definitive diagnosis for poor performance or lameness had been made were included in the study. Horses with a substantial response to infiltration of local anesthetic solution around the sacroiliac joint regions were included in the affected group (n = 27). Horses for which the source(s) of pain was confirmed by diagnostic anesthesia to be distant to the lumbosacral region were included in the control group (n = 5).
Of the affected horses, 24 (89%) had concurrent hindlimb lameness, 13 (48%) had concurrent forelimb lameness, 6 (22%) had neurological gait deficits and 2 (7%) had axial skeleton pathology.
Of the unaffected horses, 3 (60%) had concurrent hindlimb lameness, 3 (60%) had concurrent forelimb lameness and 2 (40%) had axial skeleton pathology. The pelvic regions were isolated, and the soft tissues were assessed grossly.
Sections of the lumbosacral plexus and cranial gluteal, sciatic and obturator nerves were examined histologically. The osseous specimens were evaluated for anatomical variants and abnormalities.
Gross discoloration of the sciatic or obturator nerves was observed in 7 (26%) affected and no control horses. Grade 3/3 histological abnormality scores were assigned in 22% of nerve sections from affected horses compared with 3% from control horses.
Several osseous variants (bifid sacral spinous processes, straight-shaped sacroiliac joint surface, short arrow-shaped sacral alae, left-right asymmetry of sacral alae, sacral curvature, absence of the fourth to fifth and ankylosis of the fifth to sixth lumbar articular process joints, left-right asymmetry of caudocranial position of the fourth to fifth and lumbar-sacral articular process joints) and abnormalities (sacroiliac enthesopathy, extra ventral sacroiliac joint surface, lumbosacral symphyseal periarticular modeling, lumbosacral intertransverse joint pitting lesions) were more frequently observed in affected horses.
Bottom Line: Lumbosacral region pain might reflect the presence of a number of pathological changes. Neural pain could play an important role in some horses.
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