Laika died a few hours after launch from stress and overheating. Her true cause of death was not made public until decades after the flight. Previously, officials had stated that she was euthanized by poisoned food, or that she had died when her oxygen ran out. Some former Soviet scientists have since expressed regret for allowing Laika to die.

In the Soviet Union, there was less controversy, as the Soviet people perceived exploits and personal sacrifices as normal and neither the media, nor books in the following years, nor the public questioned the decision to send the dog into space to ultimately die. However, in 1998, Oleg Gazenko, one of the leading scientists responsible for sending Laika into space, did express regret for allowing her to die: "The more time passes, the more I am sorry about it. We did not learn enough from the mission to justify the death of the dog."
-http://en.wikipedia.org/wiki/Laika

Personally, I would apologize to the 300,000 lithuanians, the 2 million cossacks, and the 8 million Ukranians before I apologized about a dog.

It is easier to show remorse when the initial action and the consequences are both trivial.