My cat was recently diagnosed with a hyperthyroid so I'm interested in your inquiry as well. Hyperthyroid is one the most common hormone disorders in felines, so I suspect there is a higher percentage there. Since I am not certain, I recommend the following web site....
....I came across the blog of Dr. Mark Peterson, DVM, a world-renowned specialist in feline endocrinology. I have not had the chance to peruse his blog/written publications, but I am pretty certain he has the answers you're looking for. In any case, it's a very informative blog to read.
http://www.drmarkepeterson.com/