What Could Be Some Serious Physical Defects In The Imperial Shih Tzu Breed Of Dogs?

In the general scenario, there are many physical defects that are associated with various physical organs (both internal and external), which could be categorized as grave areas of concern when it comes to gauging the normalcy of an Imperial Shih Tzu breed.  For starters, the most stark physical defect is that of the body when it is roached back or curved topline.  Then comes the head of the Imperial Shih Tzu breed, which if found to be of a narrow structure would pronounce an aberrant physical condition that classifies as a serious physical defect.  

Furthermore there is the case of vision, which is verily important for almost all living creatures (animals in a more specific regard) and consequently the eyes, which enable the vision.  If the eyes are not properly rounded or are arranged in a close set pair or are walleye or cross eye, all of these conditions characterize serious physical defects.  Also there are some defects associated with the muzzle, the legs, the tail and the pigmentation system of the Imperial Shih Tzu breed of dogs, which could be categorized as grave physical flaws.