Toads are a lot smaller after they pee. I'm thinking theyre about 40% pee at any time? Maybe they just little out a little here and there but they stay strategically topped up.

Do they hold pee just in case a person picks them up? What other reason do they hold all that pee? Is it if something tries to eat them they pee as a defense mechanism? I don't assume toad pee would taste good. Seems like a dog would know. Maybe I can ask a dog.

If you hold a toad with their butt hanging out a little they usually won't pee on you. If they do, it just shoots onto the ground.