Introduction: Ninety-two percent of Cavalier King Charles Spaniels (CKCS) have a skull malformation
called Chiari-like malformation (CM). CM is frequently associated with syringomyelia
(SM), an accumulation of fluid within the spinal cord that has been linked to a neuropathic
pain syndrome. The purpose of this study was to obtain quantitative data on thermal
and mechanical thresholds in CKCS with and without SM. We hypothesized that CKCS affected
with SM will have lower sensory thresholds when compared with unaffected dogs.
Materials and Methods: Fifty-four dogs were classified as symptomatic or not by their owners, presence of
pain was noted on neurological examination, sensory thresholds testing was performed,
and SM was identified on magnetic resonance imaging.
Results: Owners reported 24/54 dogs as painful, 33/54 had scratching signs, 40/54 were painful
on examination and 34/54 had SM. There was no significant difference in sensory thresholds
between dogs with and without SM (p > 0.5). Owner-reported symptomatic dogs had lower mechanical thresholds on the paw
(median: 0.367 kg) and neck (2.075 kg) compared with asymptomatic dogs (0.6275 kg
and 2.545 kg, respectively) (p = 0.009 and 0.007, respectively). Dogs that exhibited pain on neurological examination
had decreased latencies to heat at the thorax (median = 17.55 seconds) compared with
dogs that were not painful (22.16 seconds) (p = 0.03). Mechanical thresholds were lower on the side of the neck that corresponded
to lateralization of SM in dogs with asymmetrical syrinxes (p = 0.015, 0.09).
Discussion: This information can be leveraged to optimize treatment protocols and objectively
study efficacy of future therapeutics in CKCS.
Acknowledgments: Research Grant: The American Cavalier King Charles Spaniel Club Charitable Trust
through the American Kennel Club Canine Health Foundation. Student Support: AVMA/AVMF
2nd Opportunity Summer Research Scholarship; George H. Hitchings New Investigator
Award in Health Research
