The day of this posting is the 57th anniversary of the Soviet space flight of the dog, Laika.
Laika was the first animal to go into orbit around the Earth in a craft named Sputnik 2.
Due to a failure in the thermal control system of Sputnik 2, Laika died from overheating about five hours into the mission.

Here are some hotlinks to some of many videos on that story.
http://youtube.com/watch?v=ocWSY8ac6qE
http://youtube.com/watch?v=M2FDXQwb8X0 . At 2:33 on the 2nd video, the information about "systems failure on Day 6 into orbit" was originally a misrepresentation for years.
The first video, "thermal control system failure within 5 hours", is correct.
http://youtube.com/watch?v=rM46Xzf5uts .
A launch simulation is shown http://youtube.com/watch?v=O0WKiBMcygs .