Sigh, 绝育！不绝育的话，这种悲剧永远不会停，无论中国还是美国。这是美国Humane Society 的统计

每年进入美国Humane Society的猫狗等宠物是六至八百万，人道处死的三到四百万。即使有立法，又能怎样？ 人类必须控制自己的欲望，自觉承担起减少猫口狗口的社会责任。自觉限制打击靠繁殖猫狗赚钱的puppy/kitten mills 和backyard breeders

How many animals enter animal shelters each year? And how many are euthanized?

The HSUS estimates that animal shelters care for 6-8 million dogs and cats every year in the United States, of whom approximately 3-4 million are euthanized. At this time, there is no central data reporting agency for animal shelters, so these numbers are estimates; however, the Asilomar Accords method is gaining momentum as a standard for more accurately tracking these numbers. Annual statistics for approximately 150 shelters across the country are posted at asilomaraccords.org. You can help us develop a more accurate picture of the problem by encouraging your local shelters to report their data.

www.humanesociety.org/animal_community/resources/qa/common_questions_on_shelters.html

即使是以追求动物福祉和动物权利著称的Peta，2013年也处死了2000多猫狗，无语。
www.dailymail.co.uk/news/article-2552518/Animal-house-horrors-Investigation-reveals-PETA-killed-nearly-2-000-shelter-animals-2013-alone.html