Add my pet on people and places in pictures

Photos iOS does not allow us to add photos manually to the People album.

But you can create an album of all the pictures of your Pet or use the search - search for "Dog" or "Cat" whatever kind of pet you are having.

As Leonie said, sadly you can’t mark faces in Photos on iOS. You can however on macOS.

I’ve not tried it with animal faces but have had success getting it to recognise muppets and cartoon characters.

Now if only Apple would allow us to put the various people into groups.

On MacOS Photos is even recognizing faces of Monkeys.

and I managed to name various animals and the names are syncing to the iOS devices with iCloud Photos.