How common is hip dysplasia in Maine Coon cats?

Anybody who has studied the Maine Coon cat knows that hip dysplasia is a major inherited disease for this highly popular cat breed; the biggest cat breed in the world. It is a health condition which I feel undermines the status of the breed. It is a great shame that it exists and sadly I would have to argue that it is a product of human failure in the creation of this breed. 

Elderly Maine Coon with a human face. A cat more likely to have hip dysplasia because of their age. Image: Catsville County cattery

I would bet my bottom dollar that the very early Maine Coon cats, when they weren't called Maine Coon cats, did not have this level of prevalence of this hip socket problem. In fact, I would be surprised if those early cats had problems with their joints that were any worse than any other domestic cat living in America at that time.

"The condition is a genetically inherited malformation of the ball-and-socket joint that connects a cat’s thigh bone (femur) to its hip" - Cornell

Happily, I can refer to an American study for the answer to the question in the title. Although caution needs to be exercised in extrapolating this information to other areas. However, I think it provides a very good guideline and the study comes from America which is the home of the Maine Coon cat.

They assessed 2,732 unique cats of which 2,708 (99.1%) were Maine Coons and they only refer to the Maine Coons in the conclusions of this study.

They state that this was the largest demographic study of feline hip dysplasia (FHD) in the Maine Coon cat. They state that the overall prevalence (i.e. the overall occurrence) in the Orthopaedic Foundation for Animals registry of this joint disease was 24.9%. This is an average between males and females. The number is slightly higher in males at 27.3% and in females the prevalence is 23.3%.

They added that this condition is more severe when it affects both hind hip joints compared to one joint and it is more severe in older cats.

The study was published online on April 21, 2017. The study was conducted at the following institutions: Department of Orthopedic Surgery, Indiana University School of Medicine and James Whitcomb Riley Children’s Hospital, Indianapolis, IN, USA & Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA. The scientists were: Randall T Loder and Rory J Todhunter. It is published on Sage journals.

It may be useful to briefly refer to other sources. The Maine Coon Central website states that "hip dysplasia occurs in about 18% of Maine Coon cats". The nature.com website states in more general terms that it is "relatively common" in this cat breed. By comparison, a scientific website states that the general cat population has a hip dysplasia prevalence of just over 5%.