Re: Laika
I was glad to read this:
...one of the former lead scientists who had worked on the Soviet "animals-in-space" program expressed his deep regrets regarding Laika:
"The more time passes, the more I'm sorry....We shouldn't have done it....We did not learn enough from the mission to justify the death of the dog."
here.
(Perhaps not the most academic or 'official' source...but still a nice tribute to a beautiful little dog.)