Just got this email with the following link

"A new study on the prevalence of inherited disorders among American mixed breed and purebred dogs has negated the common assumption that a mixed breed dog is always healthier than a purebred dog."

http://www.thekennelclub.org.uk/item/4978

Can't say that is a surprise - I reckon if breeding was left to those who knew what they were doing the incidence of problems in the pure bred dog would be even less but at the moment pure breeds bred by pet owners, BYB and puppy farms are all lumped in together with those who spend years researching their breed and testing before they breed a proven pair of dogs together. Not saying anyone could totally eliminate problems but if any one can it will be those who take the care of the bred by testing and proving before breeding.