Lumbosacral spinal cord (L4-S3)

Disease in this region of the spinal cord typically causes signs of LMN dysfunction in the pelvic limbs and normal thoracic limbs.

Common clinical signs of a lumbosacral (L4-S3) myelopathy

  • Flaccid weakness/paralysis and ataxia in pelvic limbs
  • Decreased to absent spinal nerve & withdrawal reflexes in pelvic limbs
  • Postural reaction deficits in pelvic limbs
  • Decreased to absent muscle tone in affected limb(s) or tail
  • Early denervation muscle atrophy
  • +/- Decreased or absent cutaneus trunci reflex (lesion is usually 1-2 vertebrae cranial to cutoff)
  • +/- Paravertebral pain at site of lesion
  • +/- Root signature
  • +/- LMN bladder
  • +/- Decreased/absent anal tone or dilated anus
  • +/- Urinary or fecal incontinence


Case example of a dog with lumbosacral spinal cord signs secondary to L4-L6 fibrocartilaginous embolic myelopathy.