Just as with humans, balanced diets are essential for dogs. There are a few different things that must be present: variety of protein sources and the best representation of a prey animal that the human can get.
While it is said that variety is "the spice of life," for raw-fed pets, it is essential. Relying solely on one protein source is not only species-inappropriate, but will also create nutrient deficiencies. This spreadsheet is a wonderful resource for calculating dogs' nutritional needs. Nutritiondata.com allows users to create menus and shows nutrition information, thereby letting you know if you are feeding a balanced diet to meet your dog's needs.
It is tempting to find what works and stick with it. Certainly wild canids will encounter times when one kind of prey is plentiful and others are not. However, they do not always live on chicken farms. The most common protein source I see in the forums is chicken because it is cheap, bland, easily digested, and readily available. Unfortunately, it is not the most species-appropriate of prey. A wolf pack will not stalk a chicken. Certainly they will eat chicken if times are sparse, but their energy is much better spent on a large ungulate, like a deer or an elk. Wolves have also been known to fish for salmon and occasionally they will go after small prey, such as rabbits. The more variety you can provide your dog, the better. Even commercial kibbles are made up of a variety of meats (except for allergy formulas). A raw diet, too, should have as much variety as you can afford - this also applies to organs. A species-appropriate raw diet will be mostly (I would say 80% or more) red meat. Red meat is defined as coming from mammals, no matter what those pork commercials told you. Pork is red meat.
The goal of the prey-model diet is to create as close to what a dog would eat in the wild as possible. Of course, wild dogs consume whole prey, including organs, bones, and muscle meat. Although one dog will not consume, say, an entire deer, the individual will get a bit of each of these parts - organ, bone, and muscle. This also keeps the dog from getting bored of the same cuts of meat over and over again, which also helps clean teeth.
In order for a raw diet to be balanced, it needs to be made up of:
Obviously, when feeding whole prey, ratios don't need to be considered. Most meals will be a combination of these necessities. This is especially true with bones. For safety, bones should not be fed alone. Meat and organ cushion bone in the dog's digestive system, reducing the risk of puncture. Variety is still key! Many bones from larger animals are not edible. Variety comes more into play with meat and organs. Large animal organs (pork, beef, mutton, goat, elk, deer) are preferable to poultry organs.
Because the liver is the largest secreting organ (skin doesn't count
in raw feeding), it should make up 50% of the organ portion of the diet -
5% of the total diet.
The rest of the organs are secreting organs: kidney, spleen, pancreas,
thymus, brain, reproductive organs, etc. One mantra is "if it doesn't
secrete, feed as meat." Seeing as the heart's main function is
that of a muscle, it is fed as meat, for example. The most important
organs to feed are liver, kidney, and spleen, as they are large and
present in every prey animal. Other organs
tend to be more rare. When I was starting out, I could only find liver
and kidney. I fed a mix of these with tripe, as my dog was picky and
wouldn't eat her organs without the tripe. I currently feed a mix of
various secreting organs
from mutton and cattle that is 40% liver, 40% other secreting organs,
and 20% green tripe (stomach - counted as meaty meat). Miss will only eat the organs if they're in this mix, but Batman will eat organs alone.
Organs can be fed in a stand-alone meal, but this causes loose stools (also known as "splarts" among some raw feeders) in many dogs, so many raw feeders feed organs in smaller portions over the week or give the week's worth of organs in one day, possibly with a small bone "side dish" to keep fecal consistency. It is a matter of knowing what works best for your individual dog. The picture above shows Miss enjoying her organ meal - which is given once a week and mixed with green tripe so she will eat it. Not every meal needs to be balanced; remember balance over time!
The majority of the diet should be "meaty meat" - meat with no bone. Many other parts are considered "meat" - gizzards, stomach, intestines, lungs, heart... anything that is neither secreting organ nor bone. It is most often fed alone or with bones and organs. Variety, again, is key. If you can afford to get a variety of cuts and parts, that's ideal. Dogs will get bored eating the same cuts over and over again, and some of their teeth may get plaque on them from non-use. A variety of cuts - mostly as large as or bigger than the dog's head, to force the dog not to gulp down the meat - will keep your dog mentally engaged and also keep his teeth sparkling white.