Pchyolka (Пчёлка, “Little Bee”) and Mushka (Мушка, “Little Fly”), were the fourth and fifth soviet dogs to go to space, (Laika, Belka and Strelka coming before them) which spent a day in orbit on 1 December 1960 on board Korabl-Sputnik-3 (Sputnik 6) with “other animals”, plants and insects.
Due to a reentry error when the retrorockets failed to shut off when planned, their spacecraft was intentionally destroyed by remote self-destruct to prevent foreign powers from inspecting the capsule on 2 December and all died. Mushka was one of the three dogs trained for Sputnik 2 and was used during ground tests. She did not fly on Sputnik 2 because she refused to eat properly.
The last pic is an image of one of the dogs onboard Sputnik 6, demodulated by CIA electronic intelligence.