I have had 3 rescue dogs, 2 from a shelter and we had no idea what the previous names were. We used names we liked. The 3rd dog came via a friend and it had a spanish name, nena. Were not spanish and it's not a real name in my book
We changed it to Madi.
All 3 dogs knew their new names within a couple of days. You just have to call them and give them a treat