But Jim Crosby, a former police lieutenant who now trains officers in how to interact with dogs, isn't so sure the dog in the Facebook clip is thinking happy thoughts - although he commended the dog's restraint.
"This dog is very uncomfortable, but extremely tolerant," he told The Dodo. "If you look at the body language, he is tense, leaning away from the child from beginning, is looking away as avoidance behavior."
"The increasing level of vocalization and showing of teeth shows that he is extremely stressed, yet is holding back with a huge amount of control. When she releases, he licks - doggie for 'Thanks, please don't do that again!' - and then shows the discomfort as soon as she leans in again."
"Thank goodness for really well-temperamented dogs like this."
Sadly, if that's not a "happy growl" and the dog's patience should happen to run out, it won't just be the little girl facing an entirely avoidable injury. Parents frequently have to make the heartbreaking decision to put down their dogs after they bite.
"If, or when, this terrific dog loses it, the child will be the victim and everyone will run around wondering what went wrong," Crosby says.
Jen Deane, who runs the animal welfare group Pit Sisters, told The Dodo the video made her "cringe," but ultimately, this is a lesson in parenting.
"Videos like this should be a lesson in what not to do in allowing a child and a dog to interact," she says.
Especially since the most common victims of dog bites are children.
And it's all the more tragic since situations like the one in this video are so easily avoided.
"Parents, teach your children how to safely approach a dog and interact with a dog," Deane urges. "Instead of letting your child run up to a dog and get in the dog's face, teach your children to ask the dog's owner first if it is OK to pet the dog and then slowly approach and make a fist with a hand, letting the dog smell the child's hand first."
The American Society for the Prevention of Cruelty to Animals (ASPCA) published a comprehensive list of warning signs that a dog is acting aggressively. Some of them include becoming very still or rigid and lunging.
Read the entire list here.