Acquired syringomyelia in a dog

A n ll -year-old male Fox Terrier was referred for evaluation of progressive monoparesis in the left pelvic limb of 1 month's duration.Initially, the dog had dragged its paw and was unable to jump on a bed.The condition had worsened over the 2 weeks prior to referral.There was no recent history of trauma.On neurologic examination, postural reactions were not detected in the left pelvic limb, but were normal in the other 3 limbs.Patellar and cranial tibialis reflexes in this limb were accentuated, and withdrawal reflex was depressed.Similar, but less pronounced, reflex changes were noticed in the right pelviC limb.Deep pain sensation was intact.The panniculus reflex was depressed caudal to the L-l and L-2 dermatomes.Hyperesthesia was not elicited on palpation of the spine.Cranial nerve reflexes and micturition were normal.The only other abnormality identified on physical examination was a firm mass in the left testis.On the basis of results of the neurologic examination (left patellar and cranial tibialis hyperreflexia , decreased panniculus reflex caudal to the cranial lumbar area), the lesion was localized to the T-3 to L-3 area of the spinal cord.Depression of withdrawal reflexes was subjective, and ultimately could not be fully explained.Given the marked asymmetry of the deficits and reflex results, a leftsided lesion was suspected.Because the underlying process was chronically progressive, not associated with signs of pain, and markedly asymmetric, an intramedullary spinal cord lesion was considered a likely cause of the clinical signs.NeoplaSia was the principal possibility.An extramedullary lesion could not be completely excluded.Abnormalities identified on CBC, serum biochemical analysis, and urinalysis included slight eosinophilia (1,040 cells/~l; normal, 100 to 750 cells/~l) and high alanine transaminase (60 lUlL; normal, < 45 lUll) and bilirubin (1.0 mg/dl; normal , 0 to 0.6 mg/dl) values.Results of evaluation of cerebrospinal fluid, collected from the cerebellomedullary cistern and the lumbar subarachnoid