There are, actually, domesticated deer for eating. Any time you buy Venison at a store, you are purchasing domesticad (or "Farm Raised") deer. But you meant in a different sense. Like the horse example. Again, there really isn't anything they would be good for other than pets. Their backs are too weak for riding, and they are too small/weak for farm work. Those are the reasons the horse was domesticated in the first place. As for pets, you would need to keep them outside. That means they would need to be caged. A cage cuts off any form or escape from predators. You know where this is leading.

It might be possible to ride a moose (elk), or an elk (wapiti, or red deer) and some of the other larger deer.. The trouble with riding deer is those antlers, after riding a deer for a day you are sore on both ends. The Lapps of Finland have domesticated the reindeer for centuries. The situation is less like the horse than the cow and oxen, and is nomadic herding rather than farming. The Lapps use them for food, hides, even milk, and for pulling sleds. Children and older people do ride them as they travel from grazing ground to grazing ground. The Lapps also saw back the antlers when they harden, (BTW unlike other deer both the male and the female reindeer and the caribou(its wild American version) have antlers. The reason deer aren't more widely domesticated probably has more to do with the nature of the beast, they usually don't readily take to close contact with human domesticity. Even on those 'farms' they are basically living fenced in but in a more wild condition than most cattle or horses. Some of the venison commercially available is not so much slaughtered as it is hunted. There are a lot of 'ranches' in Texas and other states that are stocked, sometimes over stocked, with 'exotic' (non-native) species that are not regulated by game laws. "Sportsmen" pay to 'hunt' them usually just for the head and antler mount. The meat can be legally sold on the open market. Some states allow legally hunted deer to be sold. And let us not forget Santa Clause. Of course he does not ride his reindeer, at least not since the unfortunate incident which led to Donner's name being changed to Flatter.

What? you don't consider Santa's reindeer domesticated?

Besides all of the other good answers, I would have to imagine that even if you were to raise it from birth, it would still be dificult to keep it confined. They can jump quite high, I've seen even smaller deer jump over 5 feet! and they can go under and through fencing so it would be crazy to keep them locked up. M

Better lobbyists?* *A FAIRY TALE: The quail sent a "Beware of Cheney" warning memo and they got all their little white-tailed resources together and hired the best lobbyist in all the land.

They have and they haven't. Deer, unfortunately have been domesticated for food. As far as domesticating them to ride, good luck! Of all the animal species on the planet, man has only had continual success with about 14 species. For example, you might think that a Zebra could be trained like a Horse; but its nature is mean and it frightens easily.

As stated in previous answers only the larger deer species would be suitable for riding. However the reason these larger deer species (and to a lesser extent Zebras and other 'suitable' four footed herbivores) have not yet been domesticated is simply because no one ever bothered. Modern horses resulted from something in the order of three thousand years of selective breeding. Over that span of time you could breed for just about any characteristic so to say that these animals are 'unsuitable' for domestication as a previous poster has suggested is highly inaccurate. The simplest answer is generally the most accurate and that is simply that humans are lazy, when domesticated plants and animals have spread is is because the humans that support them have migrated, when you move to another location are you going to leave behind a couple hundred generations of selective breeding and start over again with another regional native species? Nope, thought not, your going to stick with what you already have unless the natives to that region have something more adaptable or useful, either way your certainly not going back to square one. Humans, through a combination of environmental and social factors, domesticated the horse at the end of the last ice age, the idea spread and as a result we have never needed to figure out what other animals could be selectively bred to ride because no one needed to mess with a winning formula.

Animals need to meet certain criteria to be able to be domesticated. They must be naturally inclined to group together, for instance, such as cattle and birds. They must have a social structure that allows people to replace the dominate figure in there social group. They must reproduce in a manner that makes them eligible for domestication. They should not compete with humans for food. Things like this are what determines whether or not an animal will be able to be domesticated.