Transient Horner's syndrome in horses following cervical plexus local anesthesia

ObjectiveTo report the development of transient Horner's syndrome in horses following local anesthesia of the cervical plexus.AnimalsA total of 37 horses.Study designObservational retrospective short case series.MethodsMedical records of cases undergoing ultrasound-guided cervical plexus anesthesia for standing prosthetic laryngoplasty at a single referral institution were evaluated (2019-2020).ResultsFive of 37 horses (14%) developed transient signs of Horner's syndrome postoperatively. Obvious clinical signs began 2 to 5 h following local anesthesia and persisted for two to 4 h. Profuse unilateral sweating of the head and upper neck was the most apparent clinical sign.ConclusionTransient clinical signs of Horner's syndrome were seen following unilateral local anesthesia of the cervical plexus. Long-term adverse sequelae were not observed.