I can tell you this as one who has rescued many a dog. once you feed it you own it...lol. not literally, but I am just saying once the dog knows you will give it food, it stays around. anyway, whether it looks healthy or not, kind or not, be cautious as any dog can attack at anytime without even meaning to. but I would feed it and give it water, (most important), and then take a picture and put up flyers in the neighborhood as well as contacting the SPCA. in the next few days you may fall in love with the dog and decide to adopt it yourself after making a good faith effort to find the dog's owner or take it to the SPCA or otherwise local organization. also consider a newspaper ad. Know that some of these animal adoption thoroughfares will only keep the animal for a week before euthanizing it. some much longer. depends on their inventory at the time. but if you intend on keeping it, take it to the vet to have the shots done, or a clinic.