Watch puppies with their mothers and you'll notice parenting styles vary widely. Some dog moms hover, constantly nudging and licking their pups, making sure each one is fed and groomed and showered with attention. Other canine mothers aren't so doting. They take care of their puppies' basic needs, but they don't coddle.

When puppies are placed in guide dog training programs, some succeed, while others just don't have what it takes to be a patient, confident assistant and companion.

In a new study, researchers suggest that the way a mother raises a puppy may be the key to its success or failure as a guide dog. The research was published in the journal Proceedings of the National Academy of Sciences.

For the study, researchers from the University of Arizona and the University of Pennsylvania followed 98 puppies from birth to adulthood. They kept track of which dogs had the most attention from their mothers as pups and which were left more to their own devices.

"Basically the puppies are kept in a kiddie pool lined with towels. So the hands-off mothers are the ones that are spending less time [in the pool] with their puppies and not interacting with them as much," lead author Emily Bray tells NPR. "Whereas a hands-on mother is going to be constantly in the pool, licking them, grooming them, interacting with them."

Only about 70 percent of the puppies were successful as guide dogs. The researchers found that those that were more actively mothered were more likely to fail the program.

Dinner time habits matter, too

golden retriever puppies nursing Puppies have to work harder when they stand up to nurse. (Photo: Ruta Zukauskaite/Shutterstock)

In addition, researchers found that how the mothers nursed their puppies had an impact on their future guide dog careers. The mothers will either lie down to nurse, or sit or stand up to feed the puppies. It's easier on the pups if the mother is lying down; if she's sitting or standing, the puppies have to work harder to eat.

"Mothers whose nursing style required greater effort by puppies were more likely to produce successful offspring, whereas mothers whose nursing style required less effort were more likely to produce offspring that failed," the researchers wrote.

The idea is that the smaller challenges of nursing and being independent as a pup likely prepare them for the larger challenges they'll face as guide dogs, Bray tells NPR.

"It's good for the puppies to have these small challenges to overcome, like not having the mother around, rather than having the mom there, around, all the time, not letting them experience things on their own," she says.

Though it might be easy to put all the blame on helicopter parenting, further research is necessary to find out why parenting styles are linked to guide dog success.

"With mothering, it seems like it's a delicate balance," Bray tells Phys.org. "It's easy to be like, 'Oh, smothering moms are the worst,' but we aren't exactly sure of the mechanisms yet and we don't want to tip too far in the other direction, either."

Mary Jo DiLonardo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.