How many times should i give my dogs a bath ? dog looses hair ?

I have 2 pitbulls and they are inside dogs but they get walked to use the potty outside. They smell good for the first hour until they go outside. But when I give my pit a bath she looses A LOT of hair but she dosent like go balled but you can rub her and your hand would have hair on it the other dogs hair dosnt do it . Should I wash her in special shampoo? If so where can I get it and how much . And is there anything I can use for the smell ?