Pet behavior

Does anyone know how to get my dog to stop barking at anything that walks on four feet like him or at least knows why some dogs get so aggressive around things that look like them? It's so hard to take my dog on a walk during summer because of this it's too hot for him to go out during the day, night and morning is where all the dogs walk. I still play with him and let him outside often to relieve himself but it would be much easier to just take him on walks more often.