Stray dogs in Russia are quite remarkable. You've probably heard of the stray dogs that have learned how to ride the subway system. It turns out that this group can also claim to be the first in space.
Laika was a stray dog, originally named Kudryavka, which is Russian for Little Curly. She was rescued from the street and trained with two other dogs. She was eventually chosen to be the first dog to orbit the Earth.
Lest you think this was a huge honor, you should know that meant she died in orbit, too. The reason stray dogs were chosen was because people thought that these animals already knew how to deal with stressful situations and not having enough food. There was never any hope of her surviving because there was no technology to come back from orbit yet.
Although Russians say she was euthanized before she ran out of oxygen. Then, the story was that she did run out of oxygen and died on day 6. In reality, she probably died from overheating because the central sustainer did not separate from the payload.