Teacup cats are simply miniature cats. They are normally about one-half to one-third the size of a regular cat of the same breed. They can be smaller than regular cats for numerous reasons, including genetics, hormones and environmental factors.
A genuine teacup cat is born with genetic dwarfism. While some miniature cats just have shorter legs, a true teacup cat is proportionately smaller in all parts of the body. Teacup cats require more care than full-sized cats. They are more fragile and vulnerable, and cats born with primordial dwarfism are predisposed to numerous health conditions and tend to have shorter lifespans.