A lot of things can make a deer look this way. Has it been very dry where you are seeing this? Drought type conditions cause the food supply to void of the proper nutrition as well as limiting water. It could also be some type of desease or heat related if you have extremely hot temeratures that are not normal for your area. I've seen this before with the whole deer herd and at times just a few animals within the herd. During the heat of the summer a lot of the South Texas deer look pretty mangy mainly due to the heat.