The Animal Medical Center began in 1906 as the brainchild of Ellin Prince Speyer when she founded the Women’s Auxiliary to the American Society for the Prevention of Cruelty to Animals (ASPCA). Believing that there were “branches of humane work especially suited for women,” Ellin and her friends developed their organization as a way to supplement the activities of the male-dominated ASPCA. The first major activity organized by the Women’s Auxilliary was the Work Horse Parade. Held on Memorial Day in 1907, the parade encouraged streetcar drivers, peddlers, and other horse owners to treat their animals better. Thousands turned out for the event, forecasting a bright future for the organization that would one day become the Animal Medical Center.

Spurred by their initial successes, in 1909 the Women’s Auxiliary set out to establish a dispensary and outpatient clinic for all animals whose owners could not afford to pay for medical treatment. The clinic opened in 1910 on the Lower East Side in the heart of New York’s largest immigrant community. Several veterinarians volunteered their services on a part-time basis while Auxiliary members and friends donated money and resources. The clinic treated 6,028 animals in the first full year.