"Our job is to protect our children and nurture them, not alter our children's appearances," Rachelle Watkins said.
Campbell defended using the botox, saying it was a pageant secret used by many pageant moms.
"This is not what pageantry is about. I'm sorry to say she's only doing a disservice to her child and will never win the title she seeks," said Valerie Walker, a veteran pageant coach.
Logan Levkoff, author of "Third Base Ain't What it Used to Be," said that giving children botox sends a terrible message to kids.
"The fact that our 8-year-olds even know what wrinkles are and would know what botox is, that's certainly a scary commentary on society today," Levkoff said.
Levkoff said that using the cosmetic procedure on a little girl promotes one standard of beauty.
"It's sending a terrible message that her worth and her success in life is measured by her face and her looks. The mother/daughter relationship is so fraught and complicated to begin with. How does this girl grow up knowing that she's going to constantly seek approval based on this one thing and these unobtainable goals," Levkoff said.
The launching of an investigation into Campbell does not mean that she will lose custody of her child, experts say. She could be redirected to parenting classes or nothing could happen at all if the botox was being administered lawfully, experts say.