>>301784
It can be a huge hassle to have to clean up foal pee after it has soaked into the carpet or furniture, not to mention the disruption if she does it in class.
I'd give her a choice. She can either be a big filly and learn to always use the toilet through a strict routine of spankings, or she can be little foal who is allowed to pee herself whenever and wherever she likes because she's always wearing protection.