Belka and Strelka.
The Soviet spacecraft Sputnik-5, launched on August 19, 1960, carried dogs Belka and Strelka and put them into orbit. The flight main purpose was to study the effects of the body overload and prolonged weightlessness on animals. The device with the surviving animals successfully returned to earth the next day. It was the first spaceflight to send animals into orbit and return them safely back to Earth.