Stars Share Adorable Pet Pics on National Puppy Day

From Julianne Hough to Zac Efron to Justin Bieber, Hollywood A-listers celebrated National Puppy Day on Monday by putting their pets in the limelight.
It seemed any star with a dog participated in the canine celebration by posting pics of their furry friends. Here's a few of our faves:
Allison Williams: "In honor of ‪#‎NationalPuppyDay‬, meet the new member of my family, Moxie. We adopted her from @animalleague, so since she's a rescue we're not exactly sure age/breed. But. My heart bursts for this lady. Even when she wakes me up at night. ‪#‎ObviNoFilter‬ ‪#‎SoTired‬ ‪#‎SoWorthIt‬."

Zac Efron: "Chappelle."
Julianne Hough: "Last #NationalPuppyDay photo of the night! Love my girls more than anything on this planet! #Lexi #harley #mommas."
NEWS: Meet Justin Bieber's New Puppy!
Justin Bieber: "Today is randomly national puppy day."
Andy Cohen: "Happy #NationalPuppyDay -- adopt, don't shop!"

Ariana Grande:
"#ophelia #nationalpuppyday #notapuppyanymore #atall #shesimmense missing my babes. lol sorry for the puppy spam but i do miss them so much (i have 6 dogs for those asking. coco, toulouse, cinnamon, fawkes, ophelia and sirius)"
Kaley Cuoco: "In honor of #muttmonday & #nationalpuppyday here are my mutt puppies :) #norm #shirls #rubes #alwayssomeonelookingovermyshoulder."
Lena Dunham: "Trying to be cool and not succumb but oh it's #nationalpuppyday and adopting this tramp is the best thing we ever did. He's so excited to meet his adopted cousin, @aw's new baby Moxie."
Betty White: "Happy #NationalPuppyDay! Today is all about celebrating puppies and encouraging adoption."

Kate Upton: "Happy #NationalPuppyDay! #AdoptDontShop."
Kellan Lutz: "Showing Bailey some love on #NationalPuppyDay! This was about a year ago when we welcomed her into the family. #GoldenRetriever"
Vanessa Hudgens: "Happy #nationalpuppyday!!! I love my little Darla so much I don't know what I'd do without her. We do everything together."
Backstreet Boys: "Happy #NationalPuppyDay!! Here's a little throwback for you..."
Marie Osmond: "Donny & Fuji, George and me!"

For more adorable puppy love, check out the video below.