We've been dogsitting a small dog (Lhasa Apso) for the past couple of days. Her owner told me to walk her 3 times a day (morning, afternoon, and evening) so that she can do her business outside. She had a small potty accident upstairs the first day, even though she's supposedly house trained (she's at least 8 human years old). So I've been letting her into my backyard every few hours because I'm afraid of another accident in the house. Almost every time we take her outside, she poops. She poops in the backyard, she even goes twice during a 10-minute walk! I've run out of potty bags my friend gave me!

My question is this: can a dog make herself poop when she goes outside? Is she going so frequently just because I let her out? Or is it something she can hold for several hours until I take her for her 3 walks, as instructed by her owner?

Thanks in advance! I'm a complete, utter newbie with dogs. I would ask my friend, but she's currently in a place with really poor cell phone reception.