title: Prevalence and heritability of symptomatic syringomyelia in Cavalier King Charles Spaniels and long-term outcome in symptomatic and asymptomatic littermates.
abstract: BACKGROUND
  Syringomyelia (SM) is common in the Cavalier King Charles Spaniel (CKCS). Dogs with syringes express clinical signs or might be clinically silent.
  
  
  OBJECTIVE
  To investigate the prevalence and heritability of symptomatic SM, the association between clinical signs and magnetic resonance imaging (MRI) findings, and long-term outcome.
  
  
  METHODS
  All CKCS registered in the Danish Kennel Club in 2001 (n = 240).
  
  
  METHODS
  A cross-sectional questionnaire-based prevalence study validated by telephone interviews and clinically investigated clinical signs of SM. Dogs were 6 years at the time of investigation. A prospective observational litter study including clinical investigations, MRI and 5-year follow-up of symptomatic and asymptomatic siblings. Heritability was estimated based on the scale of liability in the study population and litter cohort.
  
  
  RESULTS
  The cross-sectional study estimated a prevalence of symptomatic SM at 15.4% in the population. Thirteen symptomatic and 9 asymptomatic siblings participated in the litter study. Spinal cord syringes were confirmed in 21 of 22 littermates (95%). Syrinx diameter and mean syrinx : spinal cord ratio were significantly correlated with clinical signs (P < .01). Estimated heritability of symptomatic SM was 0.81. Symptomatic SM motivated euthanasia in 20%. Dogs with syringes, which expressed no clinical signs at the age of 6, remained asymptomatic in 14/15 cases (93%).
  
  
  CONCLUSIONS
  The prevalence of symptomatic SM is high and genetics have a high impact on clinical disease expression. Further investigations of factors influencing the outbreak threshold of clinical signs of SM are desirable.
authors.affiliation: Department of Veterinary Clinical and Animal Sciences, University of Copenhagen, Frederiksberg C, Denmark.
authors.forename: M S
authors.initials: MS
authors.lastname: Thøfner
authors.forename: C L
authors.initials: CL
authors.lastname: Stougaard
authors.forename: U
authors.initials: U
authors.lastname: Westrup
authors.forename: A A
authors.initials: AA
authors.lastname: Madry
authors.forename: C S
authors.initials: CS
authors.lastname: Knudsen
authors.forename: H
authors.initials: H
authors.lastname: Berg
authors.forename: C S E
authors.initials: CS
authors.lastname: Jensen
authors.forename: R M L
authors.initials: RM
authors.lastname: Handby
authors.forename: H
authors.initials: H
authors.lastname: Gredal
authors.forename: M
authors.initials: M
authors.lastname: Fredholm
authors.forename: M
authors.initials: M
authors.lastname: Berendt
mesh_terms: D000375:Aging; D000818:Animals; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D003625:Data Collection; D003718:Denmark / Q000453:epidemiology; D004283:Dog Diseases / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000235:genetics*; D004285:Dogs; D005260:Female; D007407:Interviews as Topic; D008279:Magnetic Resonance Imaging / Q000662:veterinary; D008297:Male; D015995:Prevalence; D011859:Radiography; D013595:Syringomyelia / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000235:genetics / Q000662:veterinary*
keywords: Chiari-like malformation; Dog; Epidemiologic; Genetics; Magnetic resonance imaging