Familial clustering and risk analysis for fragmented coronoid process and elbow joint incongruity in Bernese Mountain...

To analyze familial clustering and genetic risk for various forms of elbow dysplasia (ED) in Bernese Mountain Dogs (BMD) in The Netherlands and define possible means to select against ED.

98 BMD born in 1992 and 64 BMD born in 1995.

Dogs were examined radiographically when 12 to 18 months old. The population was resolved into familial clusters, and distribution of ED for the clusters was analyzed. Common ancestors associated with each form of ED were identified, and risk for having ED in the 64 offspring born in 1995 was calculated by relatedness to common ancestors. Risk was compared with radiographic outcome.

The 2 forms of ED identified were fragmented coronoid process (FCP) and elbow joint incongruity (INC). Incidence of ED decreased from 63/98 (64%) in 1992 to 29/64 (45%) in 1995. None of the familial clusters was free of FCP or INC. Common ancestors associated with FCP differed from those associated with INC. There was more potential variation in risk for FCP and INC in the 64 offspring than was achieved by breeders, indicating a decrease in population heterogeneity.

FCP and INC had differing familial sources; thus, they most likely are different genetic traits. Although incidence of ED decreased from 1992 through 1995, we did not detect variation among pedigrees in genetic risk for ED remaining in the offspring born in 1995; thus, selection among families cannot further improve ED health status of BMD in The Netherlands. Phenotypic selection within families remains the only alternative.