Relationship between parental cardiac status in Cavalier King Charles spaniels 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 disease (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 screened for clinical signs of CVD and assigned to 1 of 3 groups (late, intermediate, and early onset of CVD). The mates of these sires (30 dams) were selected and classified likewise, and 107 offspring produced in 1988 from matings between these parents were screened for clinical signs of CVD at a mean age of 5.3 +/- 0.3 years.

RESULTS

55% of the offspring were free from clinical signs of CVD, whereas 45% had cardiac murmurs of low or moderate intensity. The proportion of offspring with heart murmurs and the intensity of murmurs were significantly greater with increased parental classification. More males than females had developed murmurs, and murmurs of moderate intensity also were more prevalent in males. Results of multiple-regression analysis indicated that mean parental classification and sex had significant effects on proportion of offspring with murmurs and their intensity. Additionally, age affected disease prevalence and severity, despite the narrow range in age of offspring examined.

CLINICAL IMPLICATIONS

Parental CVD status is an important factor influencing the probability of heart murmurs and their intensity in offspring. The results of this study indicate that CVD development is a polygenic threshold trait and that sex of the offspring influences threshold levels.