What was the name of the dog sent into space?

If you mean the dog on Soviet craft Sputnik 2, launched on the 3rd of November 1957, her name was Leika/Laika.

It was a one way trip for her though, as once all the experiments of the mission were complete a radio command was sent from the ground to vent the air from the capsule. She died quickly.

She was a stray and adopted by them and after a well deseved care that she was longing, they sent her up in space and left her there alone to die in orbit. Saddest story I ever heard to be honest. To be given hope of a new life and then just left to die on purpose