Which year did the Soviet Union perform the first space flight with an animal orbiting Earth?

Explanation

Laika was only one of several Russian stray space dogs, but on 3 November 1957 it became the first living creature to orbit the Earth. The flight took place in Sputnik 2. There was no expectation of her survival as the space capsule had neither thermal insulation nor a parachute. There was food and water for several days on board, but Laika died after a few hours from overheating.