Heritability and genetic trend of body weight in dogs of different breeds in Sweden.

High body weight in dogs is often considered to cause problems, for instance, resulting in hip and elbow diseases. Furthermore, there is a huge variation in body conformation and size between different dog breeds, which is related to breeding for specific appearances and genetic traits. The aim of this study was to investigate the genetic variation of body weight within different dog breeds. To study this, we examined 19 dog breeds with an average body weight of 8 to 56 kg. We found that on average about 50% of the total variation in body weight between dogs, within a breed, depends on genetic differences, but with a range from 35% to 70% depending on breed. There were rather small changes over time in the genetic predisposition for high or low body weight; the largest changes were 0.6 kg over a 10-yr period.