Anti-raw food diet for cats zealots (frequently pet food company sales people or vets who sell dry cat food in their clinics) claim that there have been no studies about the effect of raw food on cats over a lifetime of feeding.
Well, they are incorrect. There is a study -- quite a famous one, in fact -- that was carried out on 900 cats, over 4 generations, over a 10 year period from 1932-1942, using the scientific standards of that time.
Dr. Francis Marion Pottenger, Jr. conducted this study, in which 2 different groups of cats were fed different diets. The results were conclusive -- cats being fed raw meat were many times healthier than those fed cooked food.
You can still order the book, called Pottenger's Cats: A Study in Nutrition here -- http://www.ppnf.org/catalog/product_info.php?products_id=228&osCsid=092c54af54990e5e49cf1487221f35bf
Here's another great article (be sure to hand this one to your vet)
The Carnivore Connection to Nutrition in Cats by Debra Zoran, DVM, PhD, DACVIM