Miss Egan, 35, whose previous clients include a Saudi princess with whom she also fell out over a disputed bill, offers her clients an "emergency boot camp" for their dogs. She takes pets out of their home environment and away from their owners for a fortnight to correct bad behaviour.
Other trainers argue that such sessions are useless without the presence of the owner. Otherwise, they say, dogs will revert to bad habits as soon as they go home.
The Kennel Club is also scathing about boot-camp training. "The Kennel Club would always insist that dog owners are present during training because they need to learn how to control and understand their dog if there is to be a long-lasting impact on their dog's behaviour," the club said.
Last week, Miss Egan was forced to take down a claim on her website that her company was approved by the Kennel Club after the club said it was not true. "Precious Pooch is not a training school affiliated with the Kennel Club," it said, adding: "She [Miss Egan] is nothing to do with the Kennel Club."
Emma Leicester, an internet entrepreneur who lives in Chelsea, central London, is owed more than £4,250 by Miss Egan after taking her to county court over her alleged failure to train her old English sheepdog Truffle.
Precious Pooch charged Miss Leicester £2,700 for a 14-day training programme for her exuberant puppy. The dog was biting, chasing strangers and refusing to return on command. Miss Egan took the six-month-old dog away for a fortnight but Miss Leicester said the training made no difference.
She was awarded the compensation, which includes costs and interest, in county court as long ago as 2012. Miss Leicester is now engaging bailiffs to recover the money after trying for three years to collect the debt.
Miss Leicester said: "Truffle was bitey and I wanted somebody to sort it out. Tracey came and took her away and two weeks later brought her back. There was no improvement. I told Tracey that Truffle was in a worse condition and she [Tracey] said that it was all my fault. She was very abusive."
Miss Leicester subsequently turned to another dog trainer, Winkie Spiers, chairman of Pet Dog Trainers of Europe. Miss Spiers said: "I don't think sending your dog away for training is ever going to work. People think it's a quick fix and it's not.
"When I first saw Truffle she was very hyper, very stressed; she was a little bitey. She hadn't learned anything at all. When I worked with Truffle, I trained the dog but I also trained the owner."
The extra training cost Miss Leicester a further £1,200.
The legal action brought by Miss Leicester is likely to bolster the claim made by Jenny King, 69, who is suing Miss Egan for breach of contract after paying £2,800 for boot-camp training of her fox terrier Izzy. In the end, Miss King gave her dog up after it kept biting her.
In email exchanges, Miss Egan said Izzy had been trained during boot camp but that Miss King had failed to follow her advice after the dog was returned and had failed to exercise the dog properly.
"When she first arrived I have honestly never seen such a nippy, jumpy dog," Miss Egan wrote, adding in another email. "Izzy was insane when she came to me."
She added: "If Izzy is exercised properly, off-lead, which she is trained to be now ... then she is a very sweet dog. I stick by my experience and knowledge of your dog. I do not believe that she is having the exercise she needs otherwise she wouldn't be doing these things."
Miss Egan has declined to comment.
