After nearly 100 episodes, “Dog Whisperer” producers Kay Sumner and Sheila Emery had seen everything from startlingly aggressive 10-pound Chihuahuas to mild-mannered, giant dogs that shrink from any unexpected noise or situation.

So as they migrated from Petco locations across Southern California this summer to oversee tryouts for the upcoming season of the National Geographic show, they were focused on one thing.

“We’re trying to find something new, something people haven’t seen over and over again, along with giving people help solving their common problems,” says Sumner, who was chosen along with Emery by “Dog Whisperer” Cesar Millan to produce his show out of all those hoping to develop a series around him when he noticed his dogs liked the two women the most.

The quest for that special story meant hours at each location listening to dozens of troubled pet owners who came with their desperate stories of doggie dysfunction. This year, in the interest of keeping everyone safe, the producers asked that aggressive dogs stay at home while their owners come to the tryouts with a videotape showing the behavioral problems they want to solve. And as they took each tape, Sumner and Emery did a background interview to get a sense of how far the applicants have already gone in search of a solution.

“We wanted to see if they’re doing the basics and if they’ve tried to deal with the problem with a trainer already,” Sumner says. “There are a lot of people out there who could solve a lot of issues just by exercising their dogs properly. It all comes back to exercise, discipline and affection, which are the basic things Cesar talks about.”

The most difficult cases — owners who’ve seemingly tried everything, consulted with dog professionals and vets in their area and are faced with potentially euthanizing a beloved pet — are still hard for Sumner to hear.

“Affection is never the problem,” Sumner says. “Just about everyone is giving their dog enough affection. The problem is that people are giving affection even when the dog does something you don’t want it to do, and then they get frustrated when the dog keeps stealing food or jumping on you.”

Back at the Cesar Millan Inc. production offices in Burbank, there are oodles of file boxes filled with the tapes of those seeking Millan’s help. Sumner and the rest of the production pack go through the tapes to get a sense of whether each dog’s issues are really severe enough to be featured on the show and if the owner has managed to get their dog’s problems across to potential viewers. Many tapes are put aside because they don’t actually show the problem the owner is trying to address.

“Sometimes you’ll have a tape of an owner saying their dog is really aggressive, and the dog will just be sitting there, or it will lick the owner’s hand while the person is talking about how hard it is to control the dog,” Sumner observes. “Other times we’ll get two or three (good tapes) right in a row.”

Tapes that make the cut go on to series producer-director SueAnn Fincke, who develops many of the episodes now that Sumner and Emery are involved in the ever-increasing number of Millan’s projects outside of the show itself.

Surprisingly, the one person who doesn’t usually review tapes is Cesar Millan. With the exception of situations in which the dog is potentially a threat to Millan or to the crew, he isn’t told ahead of time about the situation. Millan then goes about solving the problem — training the people and rehabilitating the dog — on the spot.

The process still amazes Sumner.

“After all this time, I think I know how he’ll approach a situation,” Sumner says. “There have been situations where I was holding my breath, but it’s always surprising because Cesar finds a way to approach and communicate with the dog that’s right for that particular dog every time.”