Is rescuing a tied up dog and taking him to the animal shelter stealing?

I just want to clarify my original question. I did call the animal shelter first but they were done for the day picking up animals. I didn't know you could call the police regarding a tied up animal. It was not my intention to take the dog. That is why I took it to the shelter. Again, I did call animal control but they only have certain pick-up hours. The woman at the shelter told me that I could bring the tied-up dog in myself. Also, guys, I feel bad and confused enough so can you tame down some of the mean comments? I mean, I welcome any opinion and everyone obviously has a right to free speech and their opinions. However, as you will see in my original question, I'm pretty stressed and confused and already took a verbal beating from the "supposed" dog owner, so I'm just asking for straightforward, non-judgemental answers. Maybe I care too much for animals and just should have left the tied-up dog to cry? Who knows how long they might have left him there and I myself was under a time constraint so I had to make a quick decision. But I do want your honest opinions about what you think I should have done.