Laika was a part Siberian husky, who was found on the streets of Moscow in 1957. She was immediately enlisted in the Russian space program, and outfitted with electrodes to monitor her vitals. Laika was launched into space on the Sputnik 2 in 1957. For many years, the Soviet Union maintained that Laika remained alive in space several days before dying painlessly. A 2002 investigative report by the BBC revealed, however, that Laika in fact died only a few hours into the mission, likely from a combination of overheating and sheer panic. It seems that Laika’s heart rate raced to higher levels than were previously thought, and that it took her far longer to calm down in zero gravity than she did in the centrifuges back on Earth. Life signs terminated about five hours into the flight. A lot was learned from Laika’ journey, but she was sadly sacrificed for the knowledge. (For more on Laika, check out this piece by /Film’s Valerie Ettenhofer.)
James Gunn knew this story, and wanted to, in some way, honor the poor fallen pooch. When a fan asked him why he changed Cosmo from a male into a female, Gunn — in his straightforward fashion — explained it plainly:
“Because Cosmo is based on Laika, the Russian dog, who was a female, so I gender-swapped her back.”
Seems simple. The authors of Marvel Comics turned Laika into a male name Cosmo, so Gunn merely rectified that. It’s likely he stuck with the Marvel Comics name just because it was copywritten by the company.