The Subchondral Split Line Patterns of the Medial Coronoid Process in Canine Ulnae

Fragmented coronoid process in the dog: a heritable disease

Fragmented coronoid process (FCP) is one of the main diseases associated with elbow dysplasia. FCP is often diagnosed in medium-to-large breed dogs with front leg lameness, for instance in Rottweilers, Labrador Retrievers and Bernese Mountain dogs. Dogs with FCP develop osteoarthrosis of the elbow joint despite conservative or surgical treatment. Although FCP is considered a hereditary condition, the gene or genes causing FCP have yet to be identified. This article provides an overview of different aspects of FCP, including elbow joint development, hypotheses about disease pathogenesis, the genetic background of FCP, and genetic methodology to identify gene or genes responsible for FCP.

Assessment of collagen genes involved in fragmented medial coronoid process development in Labrador Retrievers as determined by affected sibling-pair analysis

OBJECTIVE

To evaluate the involvement of various collagen genes in the development of fragmented medial coronoid process (FCP) in Labrador Retrievers.

SAMPLE POPULATION

93 dogs originating from 13 litters were used in the study; FCP was diagnosed in 35 dogs, and each affected dog had at least 1 sibling that was also affected. Twelve dams and sires were included in the analysis. All dogs were purebred Labrador Retrievers except for 2 litters (offspring of a female Golden Retriever-Labrador Retriever mixed-breed dog).

PROCEDURES

For each dog, DNA was isolated from blood samples. Polymorphic microsatellite markers adjacent to 14 candidate genes (ie, COL1A1, COL1A2, COL2A1, COL3A1, COL5A1, COL5A2, COL6A3, COL9A1, COL9A2, COL9A3, COL10A1, COL11A1, COL11A2, and COL24A1) were analyzed by use of PCR assays; genotypes were determined via automated detection of DNA products. The level of allele sharing between pairs of affected siblings was assessed.

RESULTS

Among the 93 dogs, allele sharing of the 14 collagen genes was determined as follows: COL1A1, 45%; COL1A2, 47%; COL2A1, 37%; COL3A1, 32%; COL5A1, 43%; COL5A2, 32%; COL6A3, 36%; COL9A1, 45%; COL9A2, 49%; COL9A3, 38%; COL10A1, 46%; COL11A1, 52%; COL11A2, 47%; and COL24A1, 47%.

CONCLUSIONS AND CLINICAL RELEVANCE

Because siblings share 50% of their genome at random, the fact that the percentages of allele sharing among the analyzed collagen genes were not significantly > 50% indicates that these genes are not determinant candidates for FCP in Labrador Retrievers. The gene for the vitamin D receptor could also be excluded because of its proximity to COL2A1.