It can sometimes be a tricky adjustment, introducing a newborn to your furry family, but Josh Duhamel's
dog Zoe has 4½-month-old son Axl all figured out.
"It's really funny now to see them both," Duhamel told PEOPLE at the Sundance Film Festival
on Monday. "He's fascinated by her ... [Axl is] really starting to pay a lot of attention to her and [the dog] sees him strictly as a potential ball thrower."
Watching their budding friendship take shape has been "awesome," says the actor, who adds, "[Zoe] knew how much we loved this new little addition to the family and she knew that inherently."
"It's all been good. She's a very sweet dog," Duhamel continues, "[and] she knows pretty soon he's going to be able to play with her."
is the reason the star, who is married to singer Fergie
, stepped out in Park City, Utah,
this week, where he kicked off the Pedigree See What Good Food Can Do
campaign. The initiative celebrates the stories of shelter dogs who have found loving forever homes, and for every dog owner who shares his or her tale of what their dog means to them – using the hashtag #DogTales on Facebook, Twitter or Instagram – the pet food company will donate a bowl of food to a shelter in need.
Several years ago, Duhamel, 41, made an aging dachshund named Meatloaf part of his family, and encourages anyone in the market for a canine companion to consider adopting, as well.
"We bought [Zoe] and she's a great little dog," he says. "And then we rescued Meatloaf about a year or two later and for me there was just a noticeable difference because I think these dogs really appreciate their second chance," he said of his beloved pet, who passed away in 2012. "They know what the alternative is like, so I just felt like he was extremely appreciative of us."