Oh my god, this gets me going every time, I help to run a guinea pig rescue and have volunteered for shelters and rescues for most of my life. The link listed below is the humane society of United States http://www.hsus.org/pets/issues_affecting_our_pets/pet_overpopulation_and_ownership_statistics/hsus_pet_overpopulation_estimates.html the site reads like this Number of cats and dogs entering shelters each year: 6-8 million (HSUS estimate) Number of cats and dogs euthanized by shelters each year: 3-4 million (HSUS estimate) Number of cats and dogs adopted from shelters each year: 3-4 million (HSUS estimate) Number of cats and dogs reclaimed by owners from shelters each year: Between 600,000 and 750,000 -- 30% of dogs and 2-5% of cats entering shelters (HSUS estimate) Number of animal shelters in the United States: Between 4,000 and 6,000 (HSUS estimate) Percentage of dogs in shelters who are purebred: 25% (HSUS estimate) Average number of litters a fertile cat can produce in one year: 3 Average number of kittens in a feline litter: 4-6 In seven years, one female cat and her offspring can theoretically produce 420,000 cats. Average number of litters a fertile dog can produce in one year: 2 Average number of puppies in a canine litter: 6-10 In six years, one female dog and her offspring can theoretically produce 67,000 dogs. On a site called Petfinder as I was answering this question, the list below is the amout of animal that are sitting in shelters or rescues waiting for a forever home. most are in shelters that euthanize, and we keep buying them from the petstores how sad. BarnYard 183 Birds 1017 Cat 105695 Dog 109924 Horse 1161 Pig 173 Rabbit 4538 Reptile 346 Small&Furry 3626 Total: 226663 pet listings and 472 breeds. National Stats for dags. The sad fact is once a puppy is past its cuteness; or a dog displays behaviors we do not know how to deal with, many canines are discarded like old newspapers. On average 100,000 dogs and puppies are listed on www.petfinder.com, daily. The National Council reports it on Pet Population Study and Policy, from the 5000 or so US agencies who responded to the survey, that over 2 million dogs enter shelters annually. Of those 27% are relinquished by owners, 42% are turned in by animal control, 31 by other sources, of these dogs, 56% are euthanized.