Just because I think the article might be confusing, when it says that she shot "the other dog", they're not referring to the one of two dogs passing by that didn't attack. She shot the attacking dog, which was a pitbull.

> Roh said surveillance video indicated that Maguire had been sitting on a bench when the pit bull rushed forward and pulled the dog off her lap, causing Maguire to intervene and try to separate the animals before drawing her weapon and shooting the pit bull in its hindquarters at close range.

From The Inquirer.