In the Sorcerer's Stone, it says first years are allowed to bring an owl, cat, یا toad. Then why is Ron allowed to bring his rat?

Joahn Rowling کہا in a very حالیہ interview to some شائقین that asked her ,the same سوال ,with آپ and کہا that Rats are allowed in the school coz of a very ancient tradition in Howarts.Hope I helped you!

Thats a good سوال because in POA Ron کہا the چوہا was Percy's first.

Maybe the owl, cat, and toad are the common ones and they don`t name the unusual ones.