RELATIONSHIP BETWEEN PARENTAL CARDIAC STATUS IN CAVALIER-KING-CHARLESSPANIELS AND PREVALENCE AND SEVERITY OF CHRONIC VALVULAR DISEASE IN OFFSPRING

Objective-To study the relationship between parental cardiac status in Cavalier King Charles Spaniels and development of chronic valvular di sease (CVD) in offspring. Design-Historical cohort. Animals-54 female and 53 male Cavalier King Charles Spaniel offspring. Procedure-7 sires , selected on the basis of their liability to develop CVD, were screen ed for clinical signs of CVD and assigned to 1 of 3 groups (late, inte rmediate, and early onset of CVD). The mates of these sires (30 dams) were selected and classified likewise, and 107 offspring produced in 1 988 from matings between these parents were screened for clinical sign s of CVD al a mean age of 5.3 +/- 0.3 years. Results-55% of the offspr ing were free from clinical signs of CVD, whereas 45% had cardiac murm urs of low or moderate intensity, The proportion of offspring with hea rt murmurs and the intensity of murmurs were significantly greater wit h increased parental classification. More males than females had devel oped murmurs, and murmurs of moderate intensity also were more prevale nt in males, Results of multiple-regression analysis indicated that me an parental classification and sex had significant effects on proporti on of offspring with murmurs and their intensity. Additionally, age af fected disease prevalence and severity, despite the narrow range in ag e of offspring examined. Clinical Implications-Parental CVD status is an important factor influencing the probability of heart murmurs and t heir intensity in offspring. The results of this study indicate that C VD development is a polygenic threshold trait and that sex of the offs pring influences threshold levels.