title: Breeding Restrictions Decrease the Prevalence of Myxomatous Mitral Valve Disease in Cavalier King Charles Spaniels over an 8- to 10-Year Period.
abstract: BACKGROUND
  Cavalier King Charles Spaniels (CKCS) are predisposed to myxomatous mitral valve disease (MMVD). Studies have indicated a strong genetic background.
  
  
  OBJECTIVE
  The aim of this study was to evaluate the effect of a breeding scheme involving auscultation and echocardiography.
  
  
  METHODS
  In the Danish Kennel Club mandatory breeding scheme, 997 purebred CKCS were examined during the period 2002-2011. Each dog was evaluated 1-4 times with a total of 1,380 examinations.
  
  
  METHODS
  Auscultation and echocardiography were performed to evaluate mitral regurgitation murmur severity and degree of mitral valve prolapse (MVP). The odds of having mitral regurgitation murmur or MVP > grade 1 in 2010-2011 compared to 2002-2003 were estimated using logistic regression analysis including age and sex as covariates. Odds were estimated for dogs that were products of the breeding scheme (defined as dogs with both parents approved by the breeding scheme before breeding) and non-products of the breeding scheme (defined as dogs with at least 1 parent with unknown cardiac status).
  
  
  RESULTS
  In 2010-2011, the odds of having mitral regurgitation murmur were 0.27 if dogs were a product of the breeding scheme compared with dogs in 2002-2003, reflecting a 73% decreased risk (P < .0001). If non-products of the breeding scheme examined in 2010-2011 were compared with dogs in 2002-2003, no difference in odds was found (P = .49).
  
  
  CONCLUSIONS
  A mandatory breeding scheme based on auscultation and echocardiography findings significantly decreased the prevalence of MMVD over the 8- to 10-year period. Such a breeding scheme therefore is recommended for CKCS.
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark.
authors.forename: A C
authors.initials: AC
authors.lastname: Birkegård
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark.
authors.forename: M J
authors.initials: MJ
authors.lastname: Reimann
authors.affiliation: Department of Biostatistics, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark.
authors.forename: T
authors.initials: T
authors.lastname: Martinussen
authors.affiliation: Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Häggström
authors.affiliation: Novo Nordisk A/S, Maaloev, Denmark.
authors.forename: H D
authors.initials: HD
authors.lastname: Pedersen
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark.
authors.forename: L H
authors.initials: LH
authors.lastname: Olsen
mesh_terms: D000818:Animals; D001947:Breeding / Q000592:standards*; D004283:Dog Diseases / Q000235:genetics*; D004285:Dogs; D020022:Genetic Predisposition to Disease; D008945:Mitral Valve Prolapse / Q000235:genetics / Q000662:veterinary*; D012189:Retrospective Studies
keywords: Dog; Genetics; Inheritance; Mitral valve prolapse