I think I'm blind and can't find the button...
How do you change the name of a pet / domesticated animal?
As far as I know you cannot; your colonists will name them for you when they get attached enough.
Only way to rename pets is to download the Animals tab from the Steam Workshop.
You can also edit your colony's save file, which is plain text, and change the name.
There was a post somewhere on the forums with detailed instructions... I will try to find and post it.
You change the name of colonists but sadly you can not change name of pets