Mr. Millan’s sexism is laughable; his ethology is outdated.

The notion of the “alpha pack leader” dominating all other pack members is derived from studies of captive packs of unrelated wolves and thus bears no relationship to the social structure of natural packs, according to L. David Mech, one of the world’s leading wolf experts. In the wild, the alpha wolves are merely the breeding pair, and the pack is generally comprised of their juvenile offspring and pups.

“The typical wolf pack,” Dr. Mech wrote in The Canadian Journal of Zoology in 1999, “is a family, with the adult parents guiding the activities of a group in a division-of-labor system.” In a natural wolf pack, “dominance contests with other wolves are rare, if they exist at all,” he writes.

That’s a far cry from the dominance model that Mr. Millan attributes to the innate need of dogs by way of wolves.

Unlike their wolf forebears, dogs exist in human society. They have been selectively bred for 15,000 or more years to live with people. Studies have shown that almost from birth they are attentive to people, and that most are eager to please, given proper instruction and encouragement.

But sometimes the relationship goes very wrong, and it is time to call on a professional.

Aggression is perhaps the most significant of the behavioral problems that may afflict more than 20 percent of the nation’s 65 million dogs, because it can lead to injury and death. Mr. Millan often treats aggression by forcing the dog to exercise extensively on a treadmill, by asserting his authority over the dog by rolling it on its back in the “alpha rollover,” and through other forms of intimidation, including exposure to his pack of dogs.

Forcefully rolling a big dog on its back was once recommended as a way to establish dominance, but it is now recognized as a good way to get bitten. People are advised not to try it. In fact, many animal behaviorists believe that in the long run meeting aggression with aggression breeds more aggression.

More important, aggression often has underlying medical causes that might not be readily apparent — hip dysplasia or some other hidden physical ailment that causes the dog to bite out of pain; hereditary forms of sudden rage that require a medical history and genealogy to diagnose; inadequate blood flow to the brain or a congenital brain malformation that produces aggression and can only be uncovered through a medical examination. Veterinary behaviorists, having found that many aggressive dogs suffer from low levels of serotonin, have had success in treating such dogs with fluoxetine (the drug better known as Prozac).

Properly treating aggression, phobias, anxiety and fears from the start can literally save time and money. Mr. Millan’s quick fix might make for good television and might even produce lasting results in some cases. But it flies in the face of what professional animal behaviorists — either trained and certified veterinarians or ethologists — have learned about normal and abnormal behavior in dogs.