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Dogs are descended from wolves. Wolves live in hierarchical packs in which the aggressive alpha male rules over everyone else. Therefore, humans need to dominate their pet dogs to get them to behave.

This logic has dominated the canine-rearing conversation for more than five years, thanks mostly to National Geographic's award-winning show, Dog Whisperer with Cesar Millan. (See photos of a real-life hotel for dogs.)

But many experts say Millan's philosophy is based on now-debunked animal studies and that some of his techniques  most famously the alpha roll, in which he pins a dog on its back and holds it by the throat  are downright cruel. Rival trainer Victoria Stilwell has launched a competitive assault on Dog Whisperer by starring on Animal Planet's It's Me or the Dog and by spreading her system of positive-reinforcement training virtually and with troops on the ground: this June she launched a podcast (available on positively.com and iTunes) and franchised her methods to a first batch of 20 dog trainers in the U.S., the U.K., Italy and Greece. She uses positivity as a counterpoint to dominance theory and reserves her aggression for the poorly behaving humans.

The debate has its roots in 1940s studies of captive wolves gathered from various places that, when forced to live together, naturally competed for status. Acclaimed animal behaviorist Rudolph Schenkel dubbed the male and female who won out the alpha pair. As it turns out, this research was based on a faulty premise: wolves in the wild, says L. David Mech, founder of the Minnesota-based International Wolf Center, actually live in nuclear families, not randomly assembled units, in which the mother and father are the pack leaders and their offspring's status is based on birth order. Mech, who used to ascribe to alpha-wolf theory but has reversed course in recent years, says the pack's hierarchy does not involve anyone fighting to the top of the group, because just like in a human family, the youngsters naturally follow their parents' lead. (Read "Do We Love Our Dogs More Than People?")

Says Bonnie Beaver, former president of the American Veterinary Medical Association (AVMA): "We are on record as opposing some of the things Cesar Millan does because they're wrong." Likewise, the American Veterinary Society of Animal Behavior (AVSAB) issued a position statement last year arguing against the aggressive-submissive dichotomy.

It is leadership by showing a good example, not dominance, that AVSAB says owners should strive for in relation to their dogs. The organization's statement, which does not explicitly name Millan but references his terminology and some of his controversial techniques, argues that dominant-submissive relationships that do occur in nature are a means to allocate resources  a problem that rarely exists between dogs and their owners. (Nor even, AVSAB notes, among feral dogs, which live in small, scavenging groups without alphas controlling access to food and mates.) House pets, on the contrary, bark too much, jump up on you, ignore your commands, growl and nip at you because they have been inadvertently rewarded for this behavior or because they have not been trained to act differently. (See the top 10 animal stories of 2009.)

To be sure, Millan's approach to retraining is sometimes warm and fuzzy, and he has much common ground with positive-reinforcement trainers like Stilwell. Both trainers strive  as much as possible with a nonspeaking animal  to determine the psychological cause of a pup's misbehavior. Both encourage people to ignore dogs' annoying habits so as not to accidentally reward them with attention. Both agree that punishment is only effective during or within half a second after the offending behavior: yell at Butch for peeing in your kitchen after he's already walked away, and Butch will think he's in trouble for walking away. Both trainers obviously love animals.

But, AVSAB says, calling a dog's behavior aggressive, as Millan often does, should be reserved for the most violent animals, and some critics even dislike the quick smacks on the flank he gives to focus a dog's attention. "Discipline doesn't come in the form of screaming at your dog, hitting your dog or putting it into an alpha roll," says Stilwell. "When you do that, instinct tells the dog to shut down, which is mistaken for calming, but really you're making the dog more insecure."

Such insecurity can have unintended consequences. For one thing, rather than submit, your pets might lash out at you. "They may react with aggression, not because they are trying to be dominant but because the human threatening them makes them afraid," AVSAB says. For another, even if a dog looks subdued, you don't know what's going on inside. "Fear increases cortisol," says AVMA's Beaver, a professor at Texas A&M's College of Veterinary Medicine. "Long-term fear increases it significantly and can lead to long-term health problems associated with stress"  a point that Stilwell, in her melodious British accent, likes to point out to her clients on TV.

Take the example of Atlanta couple Louie Newman and Judy Griffin, who already had two Lhasa apsos when they adopted a rescue poodle named Manny. Not only did Manny pick fights with the other dogs, he also would attack Newman whenever he went near his wife or even tried to hand her the remote control. Newman and Griffin thought Manny wanted to control everyone, but Stilwell told them he was just trying to figure out his status in the household. "She said he was always tense. He didn't ever blink. I would've never thought to check if my dog blinked," says Newman, a recording executive in Nashville, who learned to relax when approaching Manny and to court him with treats. "He was really insecure. Who would have thought that? He acted like he owned the house."

Of course, letting Manny's whims rule the roost was one of the couple's big mistakes. The question is to what extent they, or any dog owner, should put him in his place. With Stilwell gearing up for her third American TV season and Millan in the middle of his sixth, the answer may be a lot simpler and less dramatic than producers would have us think. "All I have to be is one position higher than that dog," says Beaver. "I raise him to see me as a leader. Not an alpha, a leader."

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