And that's why he was particularly horrified when he watched a PETsMART groomer use his youngest dog, Mocha, as a mop, wiping up a puddle of urine she had created.
"I was speechless," he says.
And Mocha, a year old with bright black eyes, was equally shocked. "She looked at me like, 'Dad, can you believe this?'" Miller says.
Since the incident two months ago, Miller has been on a campaign to get PETsMART to fire the salon manager who cleaned up the pee with the puppy.
"I have been around dogs all my life and I don't do anything like this," says Miller. "To me, it is appalling and abusive."
He has received a refund on his $36 grooming charge for Mocha, gotten apologies from the groomer and other PETsMART officials and has spent a $50 gift card the store sent him to make amends. But he is boycotting the pet store giant and is telling everyone he knows to do the same. He says he won't rest until the groomer in question is no longer employed by the company.
In a letter to Miller, Neil Stacey, the store's western region operating vice president, says the groomer was well-intentioned and was using a form of "aversive training" recommended to her by a veterinarian. But she was not acting in accordance with the PETsMART philosophy of animal training, he said.
She has expressed remorse and vows never to do such a thing again, the letter says.
Stacey says the company will make sure all grooming salon staffers are "up to speed" on the best training techniques and vows that any further incident will result in the groomer's termination.
That's not enough, Miller says. He argues that an employee who steals would not be given a second chance.
He says training techniques are irrelevant to a groomer, whose job is to make dogs cleaner and more attractive, not teach them how to behave.
Kim Warren, a Phoenix dog groomer for more than 20 years, agrees. She says dogs often piddle in her shop, either from nervousness or just because they have to go. Owners are sometimes embarrassed, she says, but she tells them not to worry.
"A tinkle on the floor is usually a submissive gesture, especially with a puppy," she says. "But even if it's not, it's not our job to train them."
Warren, who has served on the board of the Arizona Professional Pet Groomers' Association, says the actions of the PETsMART employee were out of line.
"Mopping the floor with the dog is absolutely inexcusable," she says. "I don't know a single groomer who would do something like that."
Sticking a dog's nose in its own urine or feces has been a common disciplinary tactic. But the very idea of even punishing a pooch -- particularly a puppy --after an accident goes against today's training techniques.
Even the housebreaking advice given on PETsMART's own Web site says "never punish after the fact." It recommends merely cleaning up the mess and trying to do a better job with supervision.
And the aversive training methods to which the groomer subscribed usually entail things like squirting the pup with water or rattling a can full of pebbles to interrupt a bad behavior, according to animal care groups.
Mocha's mopping incident occurred at the 20th Street and Camelback Road store. Miller and the groomer were kneeling on the floor near the 12-pound pup, examining her coat. The groomer was showing Miller some extra matting that would require an extra charge.
Then she noticed the puddle beneath the dog.
In his letter to PETsMART, Miller recounted what she said next. "Look what someone did on my floor! You know what that means; you have to clean up your mess."
Miller says the woman then grabbed Mocha by her front paws and dragged her body through the urine.
Because Arizona's groomers are not licensed or regulated, Miller had no one other than PETsMART to complain to about what happened.
Arizona PETsMART spokesperson Lynne Adams says she understands why Miller was so upset by the incident. But she says the groomer -- a relatively new, otherwise competent employee -- had not been adequately trained. Adams says the woman knows "this can't happen again."
Warren says Miller is right to demand the groomer's termination: "If she were in my employ, she would not have worked out the day."