SYSTEMIC AND LOCAL-EFFECTS ASSOCIATED WITH LONG-TERM EPIDURAL CATHETERIZATION AND MORPHINE-DETOMIDINE ADMINISTRATION IN HORSES

Objective- The purpose of this study was to determine the systemic and local effects associated with long-term epidural catheterization and epidural morphine-detomidine administration in horses. Study Design- D evelopment of systemic or local effects was assessed by placing caudal epidural catheters in study horses and administering injections throu gh the catheters every 12 hours for 14 days. Animals- Ten horses with epidural catheters that received daily injections; six uncatheterized horses presented for euthanasia. Methods- Horses received either 0.2 m g/kg morphine sulfate and 30 mu g/kg detomidine hydrochloride or an eq uivalent volume of physiologic saline solution through epidural cathet ers. Systemic effects were compared between control and treatment hors es by measuring physical parameters and hay and water consumption, as well as by evaluating major organs after euthanasia. Local effects wer e studied by examining cerebrospinal fluid and by grading representati ve samples of the spinal cord and surrounding tissues histologically f or inflammation and fibrosis. Local effects were compared between cont rol and treatment horses, as well as between catheterized (control plu s treatment) horses and uncatheterized horses. Results- No significant difference was identified in daily variables or hay and water consump tion between control and treatment horses. No growth was obtained from cerebrospinal fluid cultures. No significant difference in cerebrospi nal fluid values or spinal tissue inflammation or fibrosis grades was shown between control and treatment horses. However, when compared wit h uncatheterized horses, cerebrospinal fluid red blood cell values wer e marginally higher and protein concentrations were significantly high er in the catheterized group. Lumbosacral and sacral spinal tissue seg ment inflammation grades, and sacral segment fibrosis grades were sign ificantly higher in catheterized horses. Conclusions- Long-term epidur al administration of a morphine-detomidine combination is not associat ed with apparent adverse systemic effects in horses. Localized inflamm ation and fibrosis seem to be catheter-related. Clinical Relevance- Po tential systemic and local effects are important considerations with l ongterm administration of a morphine-detomidine combination through in dwelling epidural catheters for alleviation of chronic musculoskeletal pain in horses. (C) Copyright 1997 by The American College of Veterin ary Surgeons.