Detomidine

In this randomized crossover clinical trial, standing AA CSF collections were performed on all horses at weekly intervals for 4 weeks. In addition to the standard morphine‐containing protocol (DM), study sedation protocols (DX, DD, and D0) were selected using non‐controlled sedatives at fixed doses commonly administered in equine practice. Each horse received all 4 sedation protocols, in random order, over the course of the study. The order in which treatments were administered was determined using an online random number generator (http://www.randomizer.org/). The person performing all CSF collection (G. Cock) was blinded to all sedation protocols for the duration of the study.
For each CSF collection, a 2‐part sedation administration model was used wherein horses are sedated with an initial dose of detomidine (Dormosedan, Zoetis, Parsippany, New Jersey) before aseptic skin preparation and then administered an additional sedation 3‐5 minutes before centesis.¹Treatment groups were as follows:

DM: detomidine 5 mg IV + morphine sulfate 30 mg IV

DX: detomidine 5 mg IV + xylazine 150 mg IV

DD: detomidine 5 mg IV + detomidine 2 mg IV

D0: detomidine 5 mg IV alone

Horses were restrained in stocks for CSF collection. The procedures were performed using standing sedation with romifidine (80 μg/kg, IV; Sedivet, Boehringer Ingelheim Vetmedica, Duluth, Georgia) or detomidine hydrochloride (10 μg/kg, IV; Dormosedan, Zoetis, Parsippany, New Jersey). Cervical and LS CSF collections were performed consecutively, and an online random number generator (https://www.randomizer.org/) was used to determine the order of sampling. Lidocaine hydrochloride (100 mg; 2%; VetOne, Boise, Idaho) was infiltrated SC and into the musculature at both C1‐C2 and LS sites before the final aseptic preparation of the skin to provide local anesthesia. Cervical and LS CSF collection was performed as previously described.4, 7, 8 An 8‐in. 18 gauge spinal needle (Mila International, Florence, Kentucky) was used for LS centesis, and a 3.5‐in. 18 gauge spinal needle (Mila International) was used for cervical centesis. A total of 5 mL of CSF were collected in 1 mL aliquots from each site. After collection of CSF, horses were administered flunixin meglumine (1.1 mg/kg IV; Banamine, Merck Animal Health, Madison, New Jersey). Whole blood (10 mL) was collected into a serum tube by venipuncture of the jugular vein. The blood was allowed to clot at room temperature, centrifuged at 3000 rpm for 15 minutes, and the serum separated and frozen at −80°C until analysis.