When Dr. Phil and Robin decided to get a dog 13 years ago, they adopted Maggie from a shelter. Dr. Phil says Maggie, who passed away this past spring, grew to be his best friend.

“I truly believe this, that when you rescue a dog, that dog knows they’ve been rescued,” he says. “I believe Maggie knew that she had been rescued, and it’s, like, they forever are devoted – like, ‘You saved me, and I’m going to devote my life to you.’”

Madeline Bernstein, president of the Society for the Prevention of Cruelty to Animals, Los Angeles, was involved when Dr. Phil adopted Maggie. Bernstein, author of the new book Designer Dogs: An Exposé Inside the Criminal Underworld Of Crossbreeding, joins Dr. Phil on Friday’s episode and shares why adopting a dog is so important – and sheds light on the dangers of designer dogs.

“Go to the shelters, adopt a dog that’s already in existence, and let’s ignore the puppy millers,” Bernstein says. “If we stop the demand, we can stop the supply, and that is really the message here.”

Learn more about the dangers of designer dogs in the video above.

Designer Dogs: An Exposé Inside the Criminal Underworld Of Crossbreeding is available now. Proceeds from the book will be donated to spcLA.