If you are playing Baldur's Gate III Early Access, as I am, you will have noticed in Patch 4 there is a new scene with Lae'zel and that adorable tiefling couple. The tieflings are talking about having a cat as a pet, since dogs aren't allowed in the city of Baldur's Gate, and Lae'zel asks what a cat is.
Watching this, you might wonder, why aren't dogs allowed?
The answer to this question can be found among the books in the Arcane Tower in the Underdark:
No animal larger than a peacock may gain entry to Baldur's Gate.
It's a city restriction, and it seems to be unpopular, at least with bear owners. What they will do if you're a druid and turn into a bear or a badger while in the city is anyone's guess. 😉
Obviously there are no toy dogs in Faerun, thus no dogs allowed in Baldur's Gate.