Subarachnoid hemorrhage and axonal degeneration after C1‐C2 cervical centesis in 2 horses

Ultrasound‐guided cervical centesis has gained popularity as a method for collecting cerebrospinal fluid (CSF) from standing horses. There are anecdotal reports of neck stiffness, regional swelling, sensitivity to palpation, and fever after the procedure. We report 2 horses with complications that occurred within days of C1‐C2 centesis and ultimately resulted in euthanasia. Both C1‐C2 centesis were performed routinely, with CSF cytologic analysis providing no evidence of blood contamination. Post‐mortem examination revealed equine degenerative myeloencephalopathy as the primary disorder causing Horse 1's initial neurologic deficits, whereas Horse 2 did not have a distinct lesion explaining the horse's deficits. Both horses had evidence of subarachnoid hemorrhage at or near the centesis site with Wallerian axonal degeneration in the cranial cervical spinal cord. Although hemorrhage with associated axonal degeneration at the cervical centesis site appears to be rare, this complication of C1‐C2 centesis should be considered as this technique gains popularity.