Cervical Epidural and Subarachnoid Catheter Placement in Standing Adult Horses

Abstract

Horses underwent either cervical epidural space (CES) catheterization or subarachnoid space (SAS) catheterization while restrained in stocks, under deep sedation (detomidine and morphine) and local anesthesia (mepivacaine 2%) block. Catheters were placed under ultrasound guidance with visualization of the dura, SAS, and spinal cord between the first (C1) and second (C2) cervical vertebrae. Following sedation and sterile skin preparation, operator 1 placed under ultrasound guidance, a 6-or 8-inch Tuohy needle with the bevel oriented caudally. For CES, a 6-inch Touhy needle was used with the hanging drop technique to detect negative pressure, and operator 2 then passed the epidural catheter into the CES. For SAS, following puncture of the dura, cerebrospinal fluid (CSF) was aspirated prior to placement of the epidural catheter. Placement into either CES or SAS was confirmed with plain and contrast radiography. Catheters were wrapped for the duration of the study. CSF cytology was assessed up to every 24 h for the study period. Horses were assessed daily for signs of discomfort, neck pain, catheter insertion site swelling, or changes in behavior. A complete postmortem assessment of the spinal tissues was performed at the end of the study period (72 h). Two horses had CES catheters and five horses had SAS catheters placed successfully. All horses tolerated the catheter well for the duration of the study with no signs of discomfort. Ultrasound was essential to assist placement, and radiography confirmed the anatomical location of the catheters. CSF parameters did not change over the study period (P > 0.9). There was evidence of mild meningeal acute inflammation in one horse and hemorrhage in another consistent with mechanical trauma. Placement of an indwelling CES or SAS catheter appears to be safe, technically simple, and well tolerated in standing sedated normal horses.

Cervical Epidural Spinal Analgesia for Acute Management of Severe Unilateral Forelimb Lameness: Case Report

“…Dural puncture is a possible adverse event associated with this epidural placement technique, as described by Hurcombe et al (14). Horses can exhibit explosive reactions if dural puncture into the subarachnoid space is inadvertently performed, which can be dangerous for the patient, nearby personnel, and equipment (24).…”

“…This case report describes the first use of a cervical epidural catheter to administer morphine to treat severe unilateral forelimb pain in a standing horse. The placement of these catheters has been described in research horses but never before in a clinical case ( 14 ). The graphical representation of the pain score and heart rate in addition to the percentage of time spent recumbent prior to and after treatment with epidural morphine indicates that this treatment effectively controlled significant forelimb pain.…”

“…Due to the lack of adequate responsiveness to systemic treatment and the > 50% of time spent recumbent, the decision was made to provide spinal analgesia by epidural morphine treatment. The gelding was sedated with detomidine (0.02 mg/kg IV, Zoetis, Parsippany, NJ, USA) for placement of a cervical epidural catheter as previously described ( 14 ). A 20 × 20 cm area to the right of the mane, caudal to the right ear, centered over the first cervical (C1) and second cervical (C2) intervertebral space was clipped and aseptically prepared.…”

“…In humans, single-dose cervical epidural steroid injections are used routinely in a clinical setting to treat neck or cervical spine pain ( 12 ), and cervical epidural catheters have been used experimentally ( 13 ). The use of cervical epidural catheters placed between the first and second cervical vertebrae using ultrasound guidance has recently been shown to be safe and technically straightforward in standing sedated horses ( 14 ). However, the clinical use of cervical epidural catheters has not been described in horses.…”

Ultrasound-guided injections of the equine head and neck: review and expert opinion

“…CSF collection can easily be performed on the standing horse, whereas myelography is commonly performed under general anesthesia [ 40 ]. These techniques can also be used for medication of the epidural or subarachnoid space or for placement of a catheter [ 23 , 30 ]. Muylle et al (1975) proposed that such catheters may facilitate administration of spinal analgesia, tetanus antitoxin, and/or anti-inflammatory therapy [ 35 ], but other potential applications also exist, such as delivery of stem cells [ 2 ].…”