Canine Hip Joint Conformation

Consensus reports on pelvic radiographs from the OFA contain information for serious breeders and concerned owners. The consensus is the result of independent review by three veterinary radiologists and is reported as one of the following categories. The first three are considered within normal radiographic limits for age and breed and are eligible for assignment of an OFA breed number if the dog was 24 months of age or older at the time of radiography.

1. Excellent Hip Joint Conformation: Superior hip joint conformation as compared with other individuals of the same breed and age.
2. Good Hip Joint Conformation: Well formed hip joint conformation as compared with other individuals of the same breed and age.
3. Fair Hip Joint Conformation: Minor irregularities of hip joint conformation as compared with other individuals of the same breed and age.

The following categories are not eligible for an OFA breed number:

4. Borderline Hip Joint Conformation: Marginal hip joint conformation of indeterminate status with respect to hip dysplasia at this time. A repeat study is recommended in 6-8 months.
5. Mild Hip Dysplasia: Radiographic evidence of minor dysplastic change of the hip joints.
6. Moderate Hip Dysplasia: Well defined radiographic evidence of dysplastic changes of the hip joints.
7. Severe Hip Dysplasia: Radiographic evidence of marked dysplastic changes of the hip joints.

Hip joint conformation (phenotype) is the radiographic appearance of the hip joints and is the outcome of interaction between a dog's hereditary makeup (genotype) and its environment. Hip joint conformation can be represented as a range from excellent to very dysplastic and shades in between these two ends of the spectrum. Traits such as this are referred to as quantitative characters and are thought to depend upon the interaction of many genes (polygenic).

Modern breeds of dogs vary widely in body size and shape and in pelvic conformation. Because of these differences, OFA classifications are based on comparisons among other individuals of the same breed and age. Knowledge of a dog's pelvic phenotype can be a valuable guide for the breeder in selection against hip dysplasia and understanding a dog's pelvic phenotype can be a useful means of estimating an individual dog's potential for an active working life.