"Unspayed" refers to a female animal, usually a cat or dog, that has not been surgically sterilized through a procedure called spaying. Full definition
A normal, annoying, sometimes disappointing, and dangerous behavior pattern seen in unspayed female dogs is pseudopregnancy (also called false pregnancy or pseudocyesis). (animalemergency.net)
In unspayed female cats, mammary gland tumors are less common than in dogs, but 85 % are cancerous and deadly. (standforanimals.org)
Pyometra is a severe uterine infection that can threaten the life of unspayed female dogs OR cats. (animalalliancecmc.org)