The cow escaped while being herded into an Alpine slaughter house July 2, The Local.fr reported.
Police unsuccessfully searched the area surrounding the slaughterhouse.
Now, many people have rallied online, calling for the cow's life to be spared, the daily Le Parisien reports.
"I think this cow is a symbol. She shows that animals have emotions, a conscience. She fled because she knew she was going to die. Today we should fight for her, to save her," a Web-user named Stephanie wrote.
"There would be no point in killing her anyway. Her meat can no longer be sold because she has escaped the traditional farming processes," added Sebastien, another online user.
The Brigitte Bardot Foundation, which fights for animal rights, has responded to the calls of the online activists, saying its facility in Normandy will welcome the cow if it is found.