Sacrosanct
Legend
I was just going to make a post asking this same question because I was reading the PHB and saw the Druid WITH A PET TIGER as a clear illustration in the Druid entry. Yes, they can cast Animal Friendship; but it has a duration of 24 hours. I guess they have to devote a permanent spell slot to "Giving Mr. Snuggles His Medicine" every day. Honestly they should make it so spending a higher level slot (let's say 3rd) makes it Permanent (so long as you only have 1 such animal).
The upside is if the GM allows you to get a PET TIGER by doing this, it will allow the ranger to get a much better pet than the ones the Beastmaster ranger gets.
That's not a pet tiger. That's a shapechanged druid.