When I was in college in the late 90's the canine studies teacher taught us the pack theory in dogs and how we have to be the pack leaders to our dogs, the pack theory was discovered by Robert Schenkel in 1947, when he thought as dog originated from wolves , you had to train your dog like that with you being the Alpha and being top dog, the method used discipline to control the dog. But during the past 20 years they have discovered that there is no such thing as top dog in wolves and they have the breeding pair and the rest of wolves are a family with no hierarchy.
In 2004 national geographic channel introduced us to Cesar Milan who was the so called Dog whisperer who used unsavory methods on tv to fix out of control dogs so that propelled the dominance theory into the spot light again. In 2016 his show got cancelled because he used for entertainment purposes a pig as bait for a dog.
When I got my first cavalier in 2007 the dominance theory was still rife and the trainers all endorsed it still, telling me I should do dominant things to show him I'm top dog like eat first because I was taught that in the wild the alpha always eat first, go through doors first and make them wait and always wins in a tug of war game.
In 2014 when I got my second cavalier I realised that I couldn't carry on with this method because its been debunked and was wrong , so I had to read and look up good books about positive reinforcement.
I've just found out im a crossover trainer for my own dogs as used the top dog method before but now I use positive reinforcement for my two recent dogs. And if I give advice to anyone I always promote the positive reinforcement method to train dogs because its kinder and doesn't stress the dog out and he enjoys the training. So now you can have a tug of war game and not win and a dog can be fed first knowing it will try not to dominate you.