No national statistical database for pet issues exists. Advocacy groups estimate various figures for pet shelter statistics. For example, 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).