San Diego Humane Society was organized on March 10, 1880, by George W. Marston and George W. Hazzard, and is the oldest and largest humane society in San Diego County. In 1934, the organization signed a contract with the City of San Diego to operate a shelter under the supervision of the County Department of Health. In 1951, the first animals were moved to the original site, located on Sherman Street (formerly a milk plant). In 2003, San Diego Humane Society moved into its new buildings on Gaines Street, where the San Diego Campus has been located ever since. Through merger agreements, they absorbed the former North County Humane Society & SPCA in Oceanside, California, in 2010, and the Escondido Humane Society in Escondido, California, in 2014. In 2014, San Diego Humane Society merged with PAWS San Diego, to expand programs that help pet owners keep their pets, making this the largest pet safety net service in San Diego. Later that year, San Diego Humane Society merged with Project Wildlife, the primary local resource for animal rehabilitation, conservation and wildlife education. In 2015, San Diego Humane Society and the San Diego Animal Welfare Coalition announced that San Diego County reached zero euthanasia for healthy and treatable animals. After working for more than a decade to manage the county's homeless animal population and increase opportunities for pet adoptions, this achievement made San Diego the largest city in the U.S. to reach this goal, and the commitment to "Stay at Zero" has remained ever since. In 2018, San Diego Humane Society opened the Pilar & Chuck Bahde Center for Shelter Medicine—the first of its kind in California. The hospital offers comprehensive shelter medicine to homeless pets and serves as a teaching hospital to train the shelter veterinarians of tomorrow. The following year, San Diego Humane Society expanded its Project Wildlife program and opened the Pilar & Chuck Bahde Wildlife Center in 2019. In 2020, San Diego Humane Society welcomed its Ramona Campus. The former Fund for Animals Wildlife Center in Ramona had been part of the Humane Society of the United States for more than two decades. With this new 13-acre Ramona Wildlife Center, the work of Project Wildlife expanded to protect and care for more injured and orphaned wildlife throughout Southern California, including native apex predators such as bears, coyotes and birds of prey. The Ramona Wildlife Center is the only place in San Diego County that can care for and rehabilitate native apex predators. Later in 2020, San Diego Humane Society opened the El Cajon Campus, taking over the management of the El Cajon Animal Shelter. With this fifth campus, they began caring for animals in East County San Diego, serving three more cities—El Cajon, La Mesa and Santee. In January 2021, California Governor
Gavin Newsom signed Bella's Act (Assembly Bill 2152) in September 2020 to go into law on January 1 to prohibit the retail sales of dogs, cats and rabbits in California. This is the first bill San Diego Humane Society sponsored. AB 2152, written by California State Assemblymember
Todd Gloria (D-San Diego), puts an end to a supply of animals who have been bred and raised in unhealthy and inhumane conditions in out-of-state puppy mills. In August 2022, San Diego Humane Society launched its Community Veterinary Program to address one of the greatest challenges in animal welfare today: access to affordable veterinary care. The program offers low-cost basic veterinary care for animals whose families may not otherwise be able to afford treatment—keeping pets healthy and out of shelters. In January 2024, San Diego Humane Society worked alongside the ASPCA and San Francisco SPCA to advocate for the passage of AB 1399, which was signed into law on January 1, 2024. The law allows veterinarians in California to establish a client-patient relationship through video technology, expanding access to care for pets across the state, especially in underserved and rural communities. In February 2024, after two years of construction, San Diego Humane Society reopened its Adoptions Center at the San Diego Campus—a major milestone in the organization's commitment to animal welfare. The redesigned facility features upgraded animal habitats, expanded outdoor spaces and a welcoming lobby to improve animal well-being and the adoption experience. In May 2025, San Diego Humane Society's Ramona Wildlife Center celebrated a world record as Hannah Shirley was officially crowned the oldest living pygmy hippopotamus in managed care at 51 years, 6 months and 2 days. == Finances==