There is a high incidence of patellar luxation (PL) in Pomeranian dogs from Thailand. DNA samples were
collected from 59 dogs originating from 15 families. PL was present in 75% of the dogs with a male:female
ratio of 1:1.95. Polymorphic microsatellites situated close to the COL6A1, COL6A3, COL9A1, COL9A2, and
COL9A3 genes were analyzed for linkage to the phenotype. Sibling-pair analysis revealed that none of
the collagen markers analyzed had a high non-parametric linkage score with the highest score, 1.56,
for COL9A2 (P = 0.07). The low LOD scores for these collagen genes indicated a non-involvement in the
pathogenesis of PL in Pomeranians. An association study with a low density single nucleotide polymorphism
(SNP) set indicated the possible involvement of a region on chromosome 7. The association of this
region remained indicative when larger groups of 43 cases and 40 controls were compared (Chi square
test P = 0.01).