Far be it from me to claim that I am an expert on this subject, but there is a great deal of information floating around about dogs that I feel compelled to challange, mostly because I have seen it proven false. Most of the misinformation is about dominant submissive paradygms, there have been alot of training methods developed predicated on the assumption that a dog is just like a wolf and it needs to be dominated. First of all, even if a dog were like a wolf it should be understood that the roles a wolf plays have little to do with streangth or dominance as we see it, they have much more to do with merit. Every role, including the alpha role, is born out of nescesity and naturally goes to whichever wolf best fulfills the role. nature shows like to display anomolies where there are fights over alpha status and even kills over it. This is very uncommon. Most of the time a young male proves to be of the right energy and the older male alpha will fall into another role or wander off. It could be female just as often, books and shows like to pretend alphas are usually male. At best testosterone tends to give more of the energy of either alpha, beta, or enforcer. Not always. The roles that exist in a wolf pack, as far as I can tell, that translate over to the behavior of dogs are as such: alpha, beta, sentry, enforcer, defuser, breeder, nurse maid. They'll all be explained shortly.
Alot of books about puppies claim that you should take the puppy that approaches you first, as that one will be healthy and will be an alpha probably. Both of these are false assumptions. Though healthy puppies would be mroe active, approaching you is not an indication of dominance or health. The role that would be likely to approach newcomers first is the beta, not the alpha. In a wolf pack the alpha tends to not do such risky things as run up to newcomers, as leadership is valuable and not to be thrown away with risks. It's simply not part of the alpha role. the beta approaches newcomers. Betas tend to be high energy and very willful, they will make dificult dogs to train but will be excellent at gaurding. Beware that a beta would be most likely to hurt someone, or another dog of all the energies, though if trained as they should be no dog should be at risk of doing this. you'll find the alpah somehwere further back in the puppy encloser. It'll be the one hanging back a bit and watching, but not approaching you and not off in the corner like some. these dogs will also be willful and potentially could hurt someone if imporperly handled, which they shouldn't be. enforcers will be the first to test you, they may come up and bite at you to see if you handle it well. If they percieve of rules they will be the ones to apply them. These are the dogs that tend to claim areas and excibit herding behaviors. If you teach these dogs to stay out of an area or off some piece of furniture and they think other animals or people are submissive to them, they will enforce this rule and try to keep them off as well. Sentries are very common and they will likely be hanging back a bit but will approach if prompted. these dogs are the first to bark at newcomers and if you own one they are the dogs that stare out the window looking for sensory information and something to alert you of. Be prepared to train them out of barking at everything, the best way to do so would be to convince them you are aware of everything going on and then they will relax a bit. Defusers, also called omega, will be the puppy hanging back in the corner. In the wild these would be the wolves that break up conflicts and take all the extra abuse. these dogs will obviously be looking for leadership and will need discipline. If a dog like this is made to think they need to be leading you, it tends to make them nuerotic because they don't feel qualified. Nurse maid is not a role puppies ever exhibit. Older females that were alpha or breeders tend to exhibit this role. This is the dog that cares for puppies even when they aren't hers, and tends to steal some from new litters, even if the litter might not be of dogs. They have been known to sptonaeuosly start nursing whether they themselves ever had puppies or not. Breeders tend to be the males that seek to breed with a dominant female, or that otherwise take the breeding role when there is no alpha pair. In the wild only the alpha pair breeds but often in the absence of one several males will compete for breeding rights these are the breeders. Again, not a puppy role, only older males may exhibit this and only in the presence of females in heat (not nescesarily other dogs though, it's the same smell trust me). They will be willful, neurotic, agitated, and obviously humping things, people, dogs, and other animals.
Understanding which role your dog is and what thier energy level is at is key in understanind what your dog needs. Not all dogs need just leadership or discipline. Energy level is a big deciever, many submissive dogs seem dominiant because they have alot of energy. These dogs tend to get distracted with smells, sights, or sounds and willfully head off after them. It's not that they think they're leading it's that they're very focused. When walking a dog, and even in the house, you need a good way to get thier attention back on you. Deep and sharp nosies tend to be corrective and the dog will get the idea. Touch them if you have to, but don't strike that isn't productive. Dogs with high energy need extra walking, potentially up tot wo hours a day. Use a tredmill if you can't take them out yourself. because of a stigma about this I must state that treadmills are not abuse unless you force them to run on them even when they want to stop.
I hope I haven't bored anyone, that's all for today.