The heritability of degenerative joint disease in the distal tarsal jointsin Icelandic horses

The heritability of radiographic signs of degenerative joint disease (DJD) in the distal tarsal joints and hind limb lameness after flexion test of th e tarsus was estimated in a population of Icelandic horses being used for r iding. Furthermore, the genetic and phenotypic correlation between the radi ographic signs and lameness was estimated. Of the 614 examined horses, aged 6-12 years, 420 belonged to progeny groups from 17 selected stallions and 194 were sired by unselected stallions. The heritability was analyzed by tw o statistical models based on the threshold liability concept, a non-linear sire model and a linear animal model. The heritability of radiographic sig ns of DJD in the distal tarsal joints was not found to be significantly dif ferent from zero. The h(2) estimate for lameness was higher and in the orde r of 0.4. A positive genetic and phenotypic correlation was identified betw een radiographic signs of DJD in the distal tarsal joints and lameness. The results indicate that the prevalence of DJD in the distal tarsal joints co uld be reduced in Icelandic riding horses by breeding selection based on fl exion test of the tarsus followed by radiographic examination. (C) 2000 Els evier Science B.V. All rights reserved.