As for what toys cause many dogs to grow bored, Pullen said, "Dogs quickly lose interest in toys with hard unyielding surfaces, and those that don't make a noise when manipulated."
The team, including colleague Ralph Merrill of the Waltham Center for Pet Nutrition, has studied canine play and dog toys for some time. Their latest study involved presenting multiple kennel-housed Labrador retrievers with one toy for 30-second periods until interaction ceased.
Prior research has looked at other dogs, but Labradors were chosen for this study "because they're are very popular pets," Merrill told Discovery News.
Bradshaw added that Labradors, due to their breeding, are one of the most playful breeds "and we had to be sure that the dogs we studied would play with the toys for a few minutes at least, otherwise we couldn't have measured what would get them playing again once they'd lost interest in the original toy."
They presented the dogs with toys of varying types, including different colors and odors. The researchers then gave the dogs a unique toy that contrasted with whatever one the canines were playing with first.