The effects of intrathecal administration of betamethasone over the dogs' spinal cord and meninges.

Purpose: To determinate the potential clinical and histological changes due the injection of betamethasone, when administered into the canine intrathecal space.

Methods: Twenty one animals were included in a random and blind manner in the study. After general anesthesia, intrathecal puncture was performed and 1 ml of the random solution was injected. The G1 dogs received 0.9% saline solution, the G2 dogs received 1.75 mg betamethasone and the G3 dogs received 3.5 mg of betamethasone. The animals were clinically evaluated for 21 days and then sacrificed. The lumbar and sacral portions of the spinal cord were removed for light microscopy histological analyses.

Results: No clinical changes were observed in any of the animals included in this study. No histological changes were observed in G1 animals. Inflammatory infiltration was observed in two dogs, one in G2, another in G3. Hemorrhage and necrosis were also seen in the G2 dog which inflammatory infiltration was detected. In other two dogs, one from G2 and another from G3, there was discreet fibrosis and thickness of the arachnoid layer which was focal in one and diffuse in the other.

Conclusion: Intrathecal administration of betamethasone caused histological changes in the spinal cord and meninges in some of the dogs involved in this study.