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 clinically relevant syringomyelia (SM) is challenging. We sought to determine common signs.

ANIMALS

One hundred thirty client-owned Cavalier King Charles spaniels with neuroaxis magnetic resonance imaging (MRI) and diagnosis of CM-P/SM. Dogs with comorbidities causing similar signs were excluded with exception of otitis media with effusion (OME).

METHODS

Retrospective study of medical records relating signalment, signs, and MRI findings. 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-groups 1 versus 2-4 and groups 1-3 versus 4-were investigated. Continuous variables were analyzed using 2-sample t-tests and analysis of variance. Associations between categorical variables were analyzed using Fisher's exact or chi-square tests.

RESULTS

Common signs were vocalization (65.4%), spinal pain (54.6%), reduced activity (37.7%), reduced stairs/jumping ability (35.4%), touch aversion (30.0%), altered emotional state (28.5%), and sleep disturbance (22%). Head scratching/rubbing (28.5%) was inversely associated with syrinx size (P = .005), less common in group 4 (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 are not SM-dependent, suggesting (not proving) CM-P causality. Wide (≥4 mm) SM is associated with signs of myelopathy and, if the dorsal horn is involved, phantom scratching (ipsilateral) and torticollis (shoulder deviated ipsilateral; head tilt contralateral).