Case Study

CT – Compressive neuropathy old the cauda equine, osteoarthritis and musculotendinopathy of the gastrocnemius in a 9 year old FS Border Collie

This 9 year old FS Border Collie dog presented with intermittent right hind leg lameness of a few weeks duration.

Image Interpretation

CT of the lumbar spine, pelvis, stifles –
LUMBAR SPINE:
The patient has a congenital asymmetrical lumbosacral transitional vertebra with incoplete fusion of the vertebral bodies of S1 & S2 and a rightsided lumbarized transverse process.
The lumbosacral disc reveals severe protrusion occupying the cross sectional area of the lumbosacral vertebral canal almost completely. Moreover the herniated disc material as well as lateralized osteophyte formations lead to moderate bilateral neuroformainal stenosis. The disc itself presents a vacuum phenomenon consistent with chronic degeneration. A moderate spondylosis deformans with lateralization is seen. The sacral roof reveals cranial telescoping, the ligamentum flavum is hyperplastic.
A moderate disc protrusion is noted at L6/7 – compressive neuropathy is not evident here at this point. There is a bridging spondylosis at L4/5.
PELVIS:
Both hip joints reveal signs of dysplasia with inadequate femoral head coverage and increased dorsolateral subluxation index as well as moderate signs of osteoarthritis.
STIFLES:
No arthropathy is noted. Both lateral fabellae reveal moderate enlargement with new bone formation. The musculotendinous origin of the lateral head of the gastrocnemius is enlarged in volume respectively.

DX

Complex and severe lumbosacral stenosis and moderate bilateral lumbosacral neuroforaminal stenosis with a congenital asymmetrical lumbosacral transitional vertebra, severe disc protrusion consistent with compressive neuropathy of the cauda equine. The CT further revealed bilateral moderate coxofemoral osteoarthritis as a consequence of hip dysplasia.

Outcome

An asymmetric lumbosacral transitional vertebra is known to increase the risk of development of cauda equina syndrome by more than 8fold. The changes of the lateral head of the gastrocnemius are suggestive for chronic musculotendinopathy which is a common finding in working shepherd dogs and a result of chronic repetitive microtrauma. Clinical correlation is warranted to define the clinical significance of the findings in this case (typically really tender on palpation). Should this be an issue in this dog, conservative treatment with rest, pain management and physical therapy is recommended which the patients usually respond well to.