A teacup dog is a miniature version of a dog that is already small. Some of the famous breeds of this size are Chihuahuas, Yorkies, and Pomeranians. Teacup dogs are famous because of their pop-cultural appearances and celebrity endorsements. Unfortunately, their cuteness comes at a cost. These dogs are prone to diseases such as hypoglycemia, fontanelles, and liver shunts, primarily because they're inbred.