Reliability of early radiographic evaluations for canine hip dysplasia obtained from the standard ventrodorsal radiographic projection

To determine reliability of preliminary evaluations for canine hip dysplasia (CHD) performed by the Orthopedic Foundation for Animals on dogs between 3 and 18 months of age. Retrospective analysis of data from the Orthopedic Foundation for Animals database. 2,332 Golden Retrievers, Labrador Retrievers, German Shepherd Dogs, and Rottweilers for which preliminary evaluation had been performed between 3 and 18 months of age and for which results of a definitive evaluation performed after 24 months of age were available. Each radiograph was evaluated, and hip joint status was graded as excellent, good, fair, or borderline phenotype or mild, moderate, or severe dysplasia. Preliminary evaluations were performed by 1 radiologist; definitive evaluations were the consensus of 3 radiologists. Reliability of preliminary evaluations was calculated as the percentage of definitive evaluations (normal vs dysplastic) that were unchanged from preliminary evaluations. Reliability of a preliminary evaluation of normal hip joint phenotype decreased significantly as the preliminary evaluation changed from excellent (100%) to good (97.9%) to fair (76.9%) phenotype. Reliability of a preliminary evaluation of CHD increased significantly as the preliminary evaluation changed from mild (84.4%) to moderate (97.4%) CHD. Reliability of preliminary evaluations increased significantly as age at the time of preliminary evaluation increased, regardless of whether dogs received a preliminary evaluation of normal phenotype or CHD. Results suggest that preliminary evaluations of hip joint status in dogs are generally reliable. However, dogs that receive a preliminary evaluation of fair phenotype of mild CHD should be reevaluated after 24 months of age