A dog owner was determined to prove her pet does, in fact, have multiple facial expressions and has gone viral as a result.

Australian shepherd Penny lives in the United States with her owner and is as adored as a pet can be, with a whole TikTok account dedicated to her antics

One particular video shared to her account, @wortheverypenny0, has gone viral after her owner had an answer for anyone who has ever said: "She doesn't have different facial expressions! She's a dog!"

The clip, shared on August 3, starts with the sweet dog looking at the camera with a normal expression before jumping to her "puppy face," big eyes appearing to beg for something nice.

It then shows her "judgemental face," with her big eyes narrowed to look very much unimpressed.

Naturally, it shows her happy face, with a big smile stretched across her maw and her tongue hanging out as she sits in an outdoor park, followed by her thoroughly annoyed, angry face after a bath.

Another expression that will be familiar to dog owners is Penny's "scared of thunder face." She has her ears pinned back, eyes wide, and mouth firmly closed as she stares out the window in horror.

TikTok users went wild for the video, which has racked up 16,000 likes and 311,000 views in a matter of days.

One commenter wrote: "You forgot crazy eyes. I KNOW she's got that one. Every Aussie does."

Another person commented, "The thunder face," while one said the "angry face is hilarious."

"The judgment face, her little smirk," a TikToker wrote, and one couldn't get over "her little eyebrows."

Scientists agree that dogs have a range of facial expressions. A 2022 study presented at the Experimental Biology meeting in Philadelphia found that dogs had developed an additional facial muscle in the thousands of years since being domesticated.

Dogs are descended from wolves, which do not have these facial muscles; according to the researchers, the muscle likely contributes to the famous "puppy dog eye" effect.

Researchers compared the facial twitch muscles of the two species. Wolves had more slow-twitch muscles, so they did not form facial expressions as rapidly, whereas dogs' facial expressions evolved to be more appealing to humans and to benefit communication between dogs and humans.

At the time, Anne Burrows, senior author of the study, told Newsweek the research was used to answer in-depth questions on how dogs use their facial expressions to interact with humans.

Newsweek reached out to @wortheverypenny on TikTok for comment.

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