Prevalence of radiographic signs of degenerative joint disease in a hospital population of cats by
S. P. Clarke, D. Mellor, D. N. Clements, T. Gemmill, M. Farrell, S. Carmichael, D. Bennett from Veterinary Record (2005) 157, 793-799.

This is a study of degenerative joint disease in a hospital population of cats.

Most of the study is concerned wit osteoarthritis, and covers the entire skeletal structure. During the study, it is mentioned that five cases of hip osteoarthritis were found to be caused by FHD. This is from 113 cats, the breed and sex is not specified for those specifically suffering degenerative disease of the hips.

It is interesting that this study and the 'population study' show ~5% and ~6% of cats exhibiting FHD.