Genetics of Hip Dysplasia in Dogs: A Guide for Breeders

By Claire Wiley, VMD, DACVIM (SAIM)

Hip dysplasia is one of the most common orthopedic conditions affecting dogs, particularly in larger breeds. As a breeder, understanding the genetic basis of hip dysplasia is essential for making informed breeding decisions and working toward reducing its prevalence in future generations.

What is Hip Dysplasia?

Hip dysplasia is a developmental disorder in which the hip joint does not fit properly into the socket, leading to joint instability, inflammation, and eventually arthritis. The condition varies in severity, with some dogs showing mild changes on radiographs and others experiencing debilitating lameness. Genetics play a significant role in the development of the disease, but the full cause is multifactorial. Environmental factors, such as diet and exercise, can influence development of the disease and the severity of clinical signs.

The Genetic Basis of Hip Dysplasia

Hip dysplasia is a polygenic, multifactorial disease. Multiple genes contribute to its development, and these genetic factors interact with environmental influences. Because of this complexity, hip dysplasia does not follow a simple dominant or recessive inheritance pattern, making selective breeding more challenging. Studies have shown that heritability estimates range from 20% to 60%, depending on the breed^1-3. This means that a significant portion of the risk is inherited, but environmental factors also play a substantial role. Even dogs with the lowest genetic risk for hip dysplasia can develop the disease.

Although specific genes involved in hip dysplasia have not been fully identified, multiple studies over the past few decades have attempted to develop a reliable genetic test. For example, a recent study published in Nature has identified genetic markers associated with hip dysplasia in Labrador Retrievers, providing new insights into its hereditary components.⁴ This study represents a significant advancement in our ability to predict and mitigate the disease through genetic screening. However, commercial genetic tests are not yet available.

Screening and Selection for Breeding

Because of the polygenic and multifactorial nature of hip dysplasia, phenotypic tests are still the best tool that breeders have available to help prevent this disease. Phenotype is the observable trait, and in this case, hip radiographs (x-rays) provide the best insight. Still, no test available right now is perfect for predicting which dogs will develop clinical signs of arthritis. The Orthopedic Foundation for Animals (OFA) and PennHIP  offer screening programs that assess the degree of hip laxity and the presence of dysplastic changes. OFA hips provide a qualitative score, whereas PennHIP provides qualitative assessment for osteoarthritis as well as a quantitative number to estimate risk of developing painful osteoarthritis later in life. PennHIP also reports an individual dog’s score along with the distribution of scores within a breed, so a breeder can understand how their dog’s number compares to the other dogs tested within the PennHIP database. Using these screening tools to aid in breeding decision-making can reduce the risk of passing on the condition to offspring. However, because of the polygenic and multifactorial nature of the disease, even dogs with normal hips can produce affected puppies.

Reducing Hip Dysplasia in Breeding Programs

To minimize the incidence of hip dysplasia in your breeding program, consider the following best practices:

1. Use Hip Screening Programs – Test all breeding dogs using OFA or PennHIP evaluations and only breed dogs with favorable scores.
2. Review Pedigree and Lineage Data – Look beyond individual scores and assess the hip health of relatives, including parents, siblings, and offspring from previous litters.
3. Incorporate Genetic Diversity – Avoid excessive inbreeding, as this can increase the expression of harmful genetic traits.
4. Control Environmental Factors – Encourage proper nutrition, controlled growth rates, and appropriate exercise in puppies to reduce stress on developing joints.
5. Track and Share Data – Work with fellow breeders, veterinarians, and geneticists to collect and share data on hip health in breeding lines.

Future Advances in Genetic Testing

Researchers are actively working to identify specific genetic markers for hip dysplasia, which may eventually lead to more precise genetic screening tools. Until then, breeders must rely on phenotypic screening, pedigree analysis, and responsible breeding practices to mitigate the disease.

By taking a proactive approach to genetic selection and environmental management, breeders can play a crucial role in reducing the prevalence of hip dysplasia and improving the overall health and longevity of their breeding lines. As veterinary professionals and researchers continue to advance our understanding of this complex condition, collaboration between breeders and the scientific community remains essential in the fight against hip dysplasia.

References

1. King, M. D. Etiopathogenesis of canine hip dysplasia, prevalence, and genetics.  Clin. North Am. Small Anim. Pract.47, 753–767. https://doi.org/10.1016/j.cvsm.2017.03.001 (2017).
2. Wood, J. L., Lakhani, K. H. & Rogers, K. Heritability and epidemiology of canine hip-dysplasia score and its components in Labrador retrievers in the United Kingdom.  Vet. Med.55, 95–108. https://doi.org/10.1016/s0167-5877(02)00090-9 (2002).
3. Wang, S. et al.Genetic correlations of hip dysplasia scores for Golden retrievers and Labrador retrievers in France Sweden and the UK.  J. 226, 51–56. https://doi.org/10.1016/j.tvjl.2017.07.006 (2017).

Kieler, I.N., Persson, S.M., Hagman, R. et al. Genome wide association study in Swedish Labrador retrievers identifies genetic loci associated with hip dysplasia and body weight. Sci Rep 14, 6090 (2024). https://doi.org/10.1038/s41598-024-56060-y