Heritability estimations for diseases, coat color, body weight, and heightin a birth cohort of Boxers

Objective To obtain heritability estimates for diseases and characteristics in Boxers. Animals Birth cohort of 2,929 purebred Boxers from 414 litters. Procedure-Heritability estimates were determined for cheiloschisis-palatosc hisis, cryptorchidism, epilepsy, stifle disorders, cardiac disorders, coat color, birth weight, and adult weight, and height. Binary traits were analy zed by use of a mixed-effects probit model. Some traits also were analyzed by use of a model that postulated monogenic inheritance. Full pedigree anal yses were performed. Variation in incidences of disease among clusters of r elated dogs was evaluated. Results-Heritability estimates were virtually zero for cardiac disorders, m edium (0.17 to 0.36) for most other traits, and high (> 0.55) for coat colo r, birth weight, and adult height. Litter effects and risk factors affected cheiloschisis-palatoschisis, heart murmur, coat color, broadly defined epi lepsy, and adult weight. Litter effects may be attributable to common envir onmental effects for littermates but also may be attributable to dominance variation caused by a recessive gene. Heritability estimates increased when stricter definitions for epilepsy and stifle disorders were used. The mono genic model did not reveal higher heritability estimates for 6 traits analy zed. Incidences for white coat differed significantly for 10 familial clust ers, confirming high heritability and effects of familial lineage. Conclusions and Clinical Relevance Results indicate that genetic improvemen t of most traits should be feasible, except for cardiac disorders. However, because most traits are influenced by environmental effects as well as gen etic effects, genetic counseling based on polygenic inheritance and use of familial information rather than strict exclusion of parents is preferred.