Clinical presentation, diagnostic findings and short-term outcome in French bulldogs with presumptive spinal only meningoencephalomyelitis of unknown origin: 15 cases (2016-2023).

Objectives: To describe clinical presentation, diagnostic findings and outcome of presumptive spinal only meningoencephalomyelitis of unknown origin in French bulldogs, and to compare clinical presentation between intervertebral disc herniation and spinal only meningoencephalomyelitis of unknown origin in this breed.

Material And Methods: Medical records of French bulldogs diagnosed with presumptive spinal only meningoencephalomyelitis of unknown origin in seven referral centres were reviewed. Clinical presentation was compared to a group of French bulldogs with intervertebral disc herniation.

Results: Fifteen French bulldogs were included. Median age at presentation was 31 months. Most dogs were presented with a chronic onset (54%), and the median duration of clinical signs before diagnosis was 21 days. The most common presentation was ambulatory paresis and proprioceptive ataxia (80%). Spinal pain was uncommon (20%). There was no preferential location between the cervical and thoracolumbar segments. In all but one case, magnetic resonance imaging revealed broad focal or multifocal, poorly defined, intramedullary lesions that typically appeared hyperintense on T2W images and isointense on T1W images with parenchymal and/or meningeal contrast enhancement in 12 dogs (80%). Median total nucleated cell count in cerebrospinal fluid was 15 cells/mm with predominance of mononuclear cells in all cases. Follow-up (available for 12 dogs, ranging from 1 month to 1 year) indicated initial positive response to various immunosuppressive treatments in all but one case, with subsequent suspected relapse in three cases. Dogs with spinal only meningoencephalomyelitis of unknown origin had longer clinical sign duration compared to intervertebral disc herniation cases (60 dogs) (21 days compared to 3 days, respectively) and less frequent spinal pain during examination (20% compared to 75%, respectively).

Clinical Significance: Spinal only meningoencephalomyelitis of unknown origin is an uncommon cause of myelopathy in French bulldogs that should be particularly considered in young adults with non-acute and non-painful presentation.