The study, published in the journal Proceedings of the National Academy of Sciences, was conducted at The Seeing Eye, an organisation in Morristown, New Jersey, that breeds, raises and trains dogs to guide visually impaired people.
"You need your mom, but moms that are too attentive don't give their puppies a chance to respond to small challenges on their own," said lead study author Emily Bray, a postdoctoral researcher at the University of Arizona in the US.
"Puppies need opportunities to deal with obstacles without their mom always being there," Bray said.
The results, showing how early interactions between puppies and their mothers seem to have lasting effects, contribute to an understanding of the long-term effects of maternal style and suggest ways that guide-dog-training organisations might better identify dogs who are more likely to succeed.
To gather information about the puppies' early life experiences, the researchers spent time taking videos and closely observing 23 mothers and their 98 puppies for their first five weeks of life.
"We wanted to know if we could differentiate the moms based on how they interacted with their puppies," Bray said.
"We documented things like her nursing position, how much time she spent looking away from the puppies and how much time she spent in close proximity to her puppies or licking and grooming them," Bray said.
Analysis of the data revealed differences across the mothers, with some being particularly attentive and others less so.
When the researchers tracked the puppies a couple of years down the line, they found that those with mothers that were more attentive were less likely to graduate from The Seeing Eye's training programme to become guide dogs.
In particular, those dogs whose mothers nursed more often lying down, as opposed to sitting or standing up, were less likely to succeed.
"If a mother is lying on her stomach, the puppies basically have free access to milk, but if the mother is standing up, then the puppies have to work to get it," said study co-author Robert Seyfarth, Professor at the University of Pennsylvania.
"A hypothesis might be that you have to provide your offspring with minor obstacles that they can overcome for them to succeed later in life because, as we know, life as an adult involves obstacles," Seyfarth added.
- IANS