UPDATE- In Houston the October 2002 World Space Congress released an interesting paper about
Sputnik-2 which might put a cap on the whole overheating issue.  This document was written by Dinitri C.
Malashenkov from the Institute of Biological Problems in Moscow.  Post flight simulations suggest that
Laika probably overheated and died of heat stress on the third or forth orbit.  So she actually survived for
only 5 to 7 hours.  The author writes, "It was practically impossible to create a reliable system for
temperature control in such a small term". -
Referring to the hurried construction of Sputnik 2.