Toxicity of chronic spinal analgesia in a canine model: neuropathologic observations with dezocine lactate

The chronic spinal toxicity of dezocine lactate was investigated in mongrel dogs. Dogs received chronic intrathecal infusion from implanted infusion pumps for 28-136 days. Infusion of saline via intrathecal catheters produced leptomeningeal fibrosis, sometimes with spinal cord compression. Dezocine lactate infusion, in addition to similar leptomeningeal changes, was also associated with severe parenchymal lesions in all cases. The exact cause of this toxicity cannot be specifically assigned; potential contributing factors include catheter-induced reaction, pH of the drug, lactate concentration, osmolality and the pharmacologic agent itself. Leptomeningeal reaction in control dogs limits the value of chronic intrathecal dog models for assessment of spinal drug toxicity.