Original sentence: A common misconception is that all pedigreed cats are less healthy than random bred cats due to inbreeding.Currently, breeders take great care to select for the healthiest animals, which has greatly reduced the incidence of health issues.Many of the worst, like PKD in Persians and HCM in Maine Coons, have been nearly eliminated due to preventive screening, long term tracking and study by geneticists.Not all pedigreed cats are excessively inbred, however, in the past, this was the case with some breeds, before the modern understanding of genetics was widely circulated
Edited sentence: A popular misconception is that pedigreed cats are prone to a number of health problems that are not generally experienced by non-pedigreed moggies (mixed-breed cats).Certainly the genetic base for many breeds is quite small and inbreeding occurs.However, ethical breeders select for healthy animals as those with major health problems do not survive long or contribute to the long term welfare of the breed