The clinical, cerebrospinal fluid, and histopathologic effects of epidural ketorolac in dogs

Objective-To evaluate the clinical, cerebrospinal fluid (CSF), and histopathologic effects of epidural ketorolac. Study Design-Blinded, randomized, placebo controlled study. Animals-Twenty-two adult mixed breed dogs with 16 treatment and 6 control dogs, weighing 14.4 to 29.8 kg. Methods-Dogs were anesthetized and epidural catheters were placed at the lumbosacral space. Catheter placement was evaluated fluoroscopically. Ketorolac (0.4 mg/kg) or placebo (5% ethanol) was administered epidurally over a 52-hour period, with 5 injections given at 12-hour intervals. At 1, 2, 4, or 8 hours after the first and last injection of ketorolac, dogs were anesthetized and CSF was obtained. Control dogs had CSF sampled 1 hour after the first and last ethanol injection. Neurologic function and pain responses were evaluated before and during the study. Selected dogs were then killed and necropsies performed. Results-None of the dogs exhibited any clinical or neurologic abnormalities during the study. No statistical difference was noted in pain response or CSF analysis between treatment and control dogs. Gross necropsy revealed gastrointestinal ulceration of varying degrees in all treatment dogs. Histopathologic analysis of the spinal cord and meninges revealed minimal focal leptomeningeal phlebitis in 2 of 8 treatment dogs and minor subdural inflammation in 1 control dog. No changes to the neural structures were noted in any dogs. Conclusions-Epidural administration of ketorolac did not cause clinical signs, alteration in CSF values, or pathologic changes to thr spinal cord when used for short duration. Gastrointestinal ulceration was common when ketorolac was administered epidurally at 0.4 mg/kg every 12 hours for 5 treatments. Clinical Relevance-This study documented the neurologic safety of epidural ketorolac in dogs before an efficacy trial can be performed. Gastrointestinal ulceration may limit use to short duration or a single injection. (C) Copyright 2000 by The American College of Veterinary Surgeons.