13/08/2019
Soms is instabiliteit bij paarden wel te ondekken maar in sommige gevallen heb je er meer voor nodig.
Lumbosacral instability
This is a unique story!
The horse in this case report is an 8 year old eventer. Since his owner has him (2 years) he is difficult to ride and lately has bucked off several people. When he does, it is unprovoked and violent and he keeps bucking until his rider is gone. Otherwise he is a sweetheart of a horse.
Initially we diagnosed him with damage to his Supraspinous ligament in the lumbar region. Rehab went well, and the lesion healed, but the horse’s behavior got worse after initial improvement.
At the next visit we found a weird pattern of sensation in his hind end, he seemed very sensitive at skin tests in the area from the lumbosacral junction to the tail, only on the right side. Even weirder, his a**l reflex was abnormal only on the right side.
This neurological pattern can only be explained with damage close to the spinal cord in the lumbosacral region with compression of root nerves as well as some spinal damage, only to the right side.
All other findings were normal, no lameness other than RH shorter stride, no abnormal findings at his lameness exam.
Imaging in this region is impossible (only MRI would give useful information, but a horse will not fit in a MRI scanner with its pelvic region), but at a repeated exam 2 months later the neurological abnormalities were exactly the same.
Based on our physical exam only, we had several options to explain this problem:
1/damage to the disk at the lumbosacral junction with protruding of the disk to the right side into the spinal ca**l and damage to the meninges (layers of tissue around the spinal cord)
2/tumor in the spinal ca**l, this was a grey horse, so a melanoma would be a possibility
3/possible EPM with very one-sided lesion.
Based on the fact we found the damaged Supraspinous ligament in the same region earlier, we thought trauma to this region causing damage to the lumbosacral junction was most likely.
The owner of the horse fully understood what was going on, and saw the horse was in pain and suffering from a problem we could not solve, and followed our advice to put the horse down.
At necropsy we found that the last lumbar vertebra had moved a bit downward from the sacral bone, causing instability. As a result, the disk in between the last lumbar vertebra and the sacral bone slipped a bit ( 1 in the picture)and was protruding into the spinal ca**l (2 in the picture). The spinal cord showed old and new bleeding in the same region (3 in the picture), damaging the meninges.
So finally the horse had major trauma to the lumbosacral region in the past (probably a fall) with damage to the meninges, which caused radiating pain in his right pelvic region and some swelling of the spinal cord, leading to the weird a**l reflex. Every time he would come under behind, the protruding disk would push into the spinal cord and the meninges, causing sharp burning and stabbing pain. No wonder he bucked so violently.
This case shows how important it is to do a good physical exam on any case with behavioral issues, this was not behavioral but caused by severe pain to the spinal cord! As you can imagine, this is not a problem that can easily be detected, so you need a specialist in sports medicine to find this!
(with many thanks to MSU Clinical Pathology for their work and pictures)