I know this. NASA’s animal fatalities were fewer and less often.

Sources:

• https://en.m.wikipedia.org/wiki/Soviet_space_dogs
• https://www.smithsonianmag.com/smithsonian-institution/sad-story-laika-space-dog-and-her-one-way-trip-orbit-1-180968728/
• https://www.nasa.gov/history/a-brief-history-of-animals-in-space/
• https://www.mygreenworld.org/blog/animals-in-space
• https://www.rbth.com/science_and_tech/2014/10/11/animals_in_space_what_does_it_take_to_be_tasked_with_explori_40531.html
• https://explore.britannica.com/explore/savingearth/laika-and-her-children-animals-in-the-space-race
• https://www.sciencenews.org/blog/wild-things/brief-history-animal-death-space