Due to their extremely small size, both teacup Chihuahuas and Yorkies are prone to a variety of medical issues not seen in the larger members of their respective breeds. (dogcare.dailypuppy.com)
Maine Coon cats and Rag Doll cats being considered for breeding should have a DNA test to determine if they are free of the genetic defect known to cause HCM in their respective breed. (uvsonline.com)