Amanda Seyfried Says She Doesn't Know How She Would've 'Navigated Hollywood’ Without Rescue Dog Finn (Exclusive)

Amanda Seyfried gets by with a little help from her furry friend.

In an exclusive conversation with PEOPLE, the actress, 38, opens up about how her rescue dog Finn changed her life for the better.

"[Pets give us] purpose. No matter what we say, we can't deny the fact that we need purpose, and to have that responsibility of taking care of animals, who don't have a voice and can't really do much for themselves, it gives you so much more than we could ever give them, really," Seyfried says.

"I don't know what my twenties would've looked like without Finn. I really don't know," continues the Mamma Mia! star, who recently partnered with Synchrony’s CareCredit and Pets Best insurance. "I don't know how I would've navigated Hollywood. I mean, I stayed out of a lot of trouble, I think, because I had that guy to come home to."

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Seyfried adopted her 15-year-old Australian shepherd while working on the set of the HBO series Big Love.

“As soon as he was mine, like 24 hours after I got him, I realized something about me needed him,” she told PEOPLE in 2019. “He completely changed my life and helped me find my solitude and my independence."

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Now, Seyfried reflects more on the moment she knew Finn was meant to be hers, telling PEOPLE, "I took him home thinking I was going to, like, find a home for him and have him for a couple of weeks, but I fell in love with him right away."

"I was just like, 'I'm going to keep him safe,' and then he just ended up keeping me safe," she continues. "I had struggled with a lot of anxiety and I have OCD, and my twenties were just hard in general, like anybody's twenties are hard, so I think he grounded me in a way that nothing else could have."

The Mean Girls star celebrated her canine companion's latest birthday last month with an Instagram carousel dedicated to him.

"Finny’s 15 🥳," Seyfried captioned a post for her four-legged friend, including images of Finn in different costumes and wigs, along with selfies of herself lounging around with her pet.

Seyfried tells PEOPLE that she cannot believe that her beloved pet is now a senior dog.

"It's insane," she says. "I feel so lucky that he's still alive and he's thriving. Keep knocking on wood."