Safety of Epidurally Administered Ketorolac in Dogs

The objective of this study was to evaluate the clinical, cerebrospinal fluid (CSF), and histopathologic effects of an epidurally administered NSAID (ketorolac) in dogs. This was performed as a blinded, placebo controlled study using twenty-two adult mixed breed dogs with 16 treatment and 6 control dogs. 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 response was evaluated before and during the study. Selected dogs were then euthanized and necropsies performed.

None of the dogs exhibited any clinical or neurological 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 one control dog. No changes to the neural structures were noted in any dogs.

Epidural administration of ketorolac did not cause clinical signs, alteration in CSF values, or pathologic changes to the 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.

This study documented the safety of epidurally administered ketorolac in dogs before an efficacy trial can be performed. Gastrointestinal ulceration may limit use to short duration or single injection.