As the result of the domestication of animals, their birth rate in domesticated environments has escalated in an uncontrolled manner, often without any adequate means to house and feed them. There is a limit to how many mongrel puppies and non-pedigree kittens can be given away to good homes. Surplus animals can experience suffering and deprivation. Since they are unwanted, they face maltreatment by their owners.
70,000 puppies and kittens are born in the USA every day. The traditional way to dispose of an unwanted litter of kittens was drowning. Over 10 million dogs and cats are put to death each year in animal shelters because no one wants them. It is estimated that in the USA alone, some 25 million animals are destroyed annually. Millions are sold to laboratories where they are the subject of animal experiments. The remainder fend for themselves as strays. No figures exist for the numbers of animals that die each year due to abandonment, neglect, abuse, starvation or cruelty because they are unwanted.
Abandoned animals create health hazards and are a public menace. Wild dogs and cats breed in streets, gutters and abandoned shelters; they are often rabid and disease ridden; they may bite humans, infect humans with fleas, and steal food from gardens or marketplaces.