Yes you are right they can contain bacteria and parasites, but a cat and dogs gastro-intestinal system functions differently from ours.
Their stomach acids are much stronger then ours and food gets digested more quickly, the digestion takes place mostly while in the stomach, their intestines are shorter then ours, thusly food passes through more quickly leave less time for any harmfull effects to take place.
You can also treat the meat with GSE or food grade H2O2 to further help prevent surface bacteria.
Apple Cider Vinager is also sometimes used to aid in digestion of the bacteria.
And of course feeding food which is only organic can help as well, making it devoid of antibiotics and steroids.
