Radiculomeningomyelitis due to Halicephalobus gingivalis in a horse

An adult horse was euthanatized following a clinical diagnosis of cauda equ ina neuritis. Significant gross postmortem and histopathologic findings wer e limited to the sacral spinal cord and cauda equina. The sacral spinal cor d, meninges, and spinal nerve roots were expanded and partially effaced by sclerosing granulomatous inflammation with necrosis. The lesion contained n umerous nematode larvae and fewer adults with a rhabditiform esophagus havi ng a corpus, isthmus, and valved bulb. Female nematodes were amphidelphic a nd didelphic with reflexed ovaries. These morphologic features confirm Hali cephalobus gingivalis as a novel cause of clinical signs in this case of ca uda equina neuritis.