The head of a French bulldog should be square shaped and large along with ears that symbolized bat ears. French bulldogs are also known as a flat faced breed. Eyes that are AKC Standard approved for French Bulldogs are dark and almost to the point of being black. Blue eyed French bulldogs are not AKC approved. The breed clubs do not recognize any other colors or patterns. This is because some colors come linked with genetic health problems not usually found in the breed. These include blue coloration, which is linked with a form of alopecia (hair loss or baldness), sometimes known as 'Blue Dog Alopecia'. Although this is heavily disputed by some organizations, it has been suggested that the health, hair and skin conditions are caused by the color pigment (melanin) clumping in the hair shaft itself.