Behavioral and clinical signs of Chiari‐like malformation‐associated pain and syringomyelia in Cavalier King Charles spaniels

Background: Diagnosis of Chiari-like malformation-associated pain (CM-P) or clinicallyrelevant syringomyelia (SM) is challenging. We sought to determine common signs.Animals:One hundred thirty client-owned Cavalier King Charles spaniels with neuroaxismagnetic resonance imaging (MRI) and diagnosis of CM-P/SM. Dogs with comorbiditiescausing similar signs were excluded with exception of otitis media with effusion (OME). Methods: Retrospective study of medical records relating signalment, signs, and MRIfindings. Dogs were grouped by SM maximum transverse diameter (1 = no SM;2 = 0.5-1.99 mm; 3 = 2-3.9 mm: 4 =≥4 mm). Differences between all groups—groups1 versus 2-4 and groups 1-3 versus 4—were investigated. Continuous variables wereanalyzed using 2-samplet-tests and analysis of variance. Associations between categori-cal variables were analyzed using Fisher's exact or chi-square tests. Results:Common signs were vocalization (65.4%), spinal pain (54.6%), reduced activ-ity (37.7%), reduced stairs/jumping ability (35.4%), touch aversion (30.0%), alteredemotional state (28.5%), and sleep disturbance (22%). Head scratching/rubbing(28.5%) was inversely associated with syrinx size (P= .005), less common in group4(P= .003), and not associated with OME (P= .977). Phantom scratching, scoliosis,weakness, and postural deficits were only seen in group 4 (SM≥4 mm;P= .004). Conclusions and Clinical Importance: Signs of pain are common in CM/SM but arenot SM-dependent, suggesting (not proving) CM-P causality. Wide (≥4 mm) SM isassociated with signs of myelopathy and, if the dorsal horn is involved, phantomscratching (ipsilateral) and torticollis (shoulder deviated ipsilateral; head tiltcontralateral)