The phrase "teacup dogs" refers to extremely small dog breeds that can fit in a teacup. They are usually bred to be much smaller than the average size of their breed. Full definition
Teacup Dogs for Adoption and Rescue from Dog Breeders and Rescue organizations in Massachusetts, MA. (scottspuppypalace.com)
On top of engaging in unethical practices and selling teacup puppies for a premium, breeders of teacup dog breeds are also giving away dogs who are likely to encounter several health ailments along the road. (pethelpful.com)