Throughout 2026, the ASPCA is sharing highlights from our organization’s rich and sometimes unexpected 160-year history.

Dogs are the most popular companion animal in the United States, living in about half of all households and numbering an estimated 700 million to 1 billion worldwide. But that popularity comes with a price: In 2025, 2.8 million dogs entered U.S. shelters. That’s why the ASPCA and other animal welfare organizations around the globe promote Adopt a Shelter Dog Month each October. Since our founding, we have worked ceaselessly to expand opportunities and resources so more homeless dogs can get the help they need and the second chances they deserve.

From Wolves to Best Friends

Scientists have long been fascinated by the bond between humans and dogs, a relationship so enduring it’s no wonder dogs are called "man's best friend."

At first glance, it’s hard to believe that a towering Great Dane and a tiny Chihuahua are cut from the same genetic cloth.…