Dogs as a matter of fact are NOT exclusively pack animals. Recently I spent a week in a small country town in eastern Europe that was full, and I mean FULL of strays. As behaviourism is one of my major interests, I studied a bit (as far as time allowed me) the way they behave, the way they act. Some of them were quite happy to stroll along alone for days, some of them were forming groups, most of them were solo.
A lot of "alpha" theories are coming from 40-50 years ago and to these day people still hold on to them and do not look outside the square. Most of those theories were made upon studies of captured wolves (not necesseraly caged, but those in reserve, national parks etc.) , and their behaviour and packing order is rather different from those in the wild (where men has no influence whatsoever). There's a great book about it all in David Mech's book "Wolves, behaviour, ecology and conservation). Mech is biologist who dedicated more then 50 years studying wolves both free and in reserves and captivity.
Also, dogs are not wolves, nor they're wolf hybrids, not even huskies or malamutes. Some breeds like Czechoslovakian wolfdog for example are. So many breeds are actually very far from wolves. So firstly - this "alpha" theory don't apply because many use it not knowing even how wolves function and for that matter they make mistakes - logically.
Dogs are social animals, and yes, they do need leadership, but not such harsh leadership the way Huskymum described.
I have dogs all my life, of all kinds and sizes, my favourite are flock guarding breeds (and they are beyond strongheaded for that matter). I never really cared if they walk in front or behind me, they all slept on my bed, I ate at my leisure not really caring if I will become less of an "alpha", they walked through doors before or after me (gosh! what a miserable life we'd all have if I was gonna be careful each second of the day for 14 years not to do that!). Most of big "no-no" stuff I did and I do and I don't know, but I never had a problem with my dogs for that matter. I won't say that I never used alpha roll, or other "wonderful" methods, because I'd be lying. Unfortunately I have, but thankfully I know better now.