Extreme dog dumping

The problem with this dog was it was not dumped at my house it was dumped at a park. They just tied the dog to a tree off a path with no food or water. So my only choice was to leave the dog to die or take the dog. I was going to let the Deputy handle it when he got there to close the park but he never showed up to close the park. I was going to just take her to animal control but my little girl got upset. I have someone going to look at the dog tomorrow. I am so ticked off about this stupid dog I never want to go to a park again. To be honest I don't deal with dumped dogs but this time I was put in a situation to either leave the dog just like it was and be just as cruel or do something. I don't think anybody is mean for shooting dumped dogs because I have had to bury some of my own dogs because I did not shoot the dumped dogs fast enough. But I can't leave a dog tied to a tree to die. This one has a great personality and would be great with a family. Believe me I tried to get the dog to do something so I could get rid of the problem. This is the only dog I have ever found that I have put this much effort into. But I am not spending the money to vet the dog and there is no way I will risk my dogs. If someone wants to pay to make sure there is a clean bill of health great. If not the dog will be gone Monday. Right now she is tied under a shade tree with food, water, and shelter right next to the road if someone wants her. If she is not gone Monday she will go to a shelter and most likely be put down thanks to all the animal rights people. So is it worse to shoot a dog to keep your dogs safe or to put a dog down in the name of being humane? I have no problem with quickly putting a dumped dog down.