Advocacy groups estimate various figures for pet shelter statistics. The ASPCA estimates that 5-7 million animals enter shelters each year, while the American Humane Association puts the figure at approximately 8 million animals.
Here are some other statistics:
Each year, about 3.7 million animals are euthanized (American Humane Association).
5 in 10 dogs and 7 in 10 cats in shelters are euthanized simply because there is no one to adopt them (ASPCA).
25 percent of shelter dogs are purebred (ASPCA).
10 to 20 percent of dogs and cats owned are adopted from shelters (ASPCA).