Chihuahuas are considered a pretty hardy breed. The health issues that plague other breeds have not found a home in the Chihuahua. There are conditions that are not common in Chihuahuas, but they do need to be mentioned and watched so they don't get a foot hold in the breed. One way to do this is to health test dogs that are used for breeding. It is not a fool proof way to keep out genetically influenced problems, but it is all we have at this time.