Sixteen percent of the approximately 90 million owned cats in the U.S., and 30 percent of the approximately 73 million owned dogs, remain unsterilized. That's 35 million animal companions who are unsterilized, and that's not even counting the millions of "unowned" animals struggling to survive on the streets.

Every animal bred and born—on purpose or by accident—and every animal purchased from a breeder or pet store occupies a home that could have taken in a dog or cat dying for a home at an animal shelter. Never breed animals or buy them from breeders or pet stores, and always practice your ABCs: Animal Birth Control.

Until people spay and neuter their animal companions, euthanasia will remain a tragic necessity. No one wants to have to euthanize animals, least of all those who hold the syringe, but every day, animal shelter workers see fates far worse than a humane death, including animals cruelly killed by mean people; animals chained, neglected, and starved; and animals left to perish on the streets, where they are considered a public health threat and a nuisance.