Footage of a German shepherd reacting to her own reflection after seeing a full-length mirror for the first time has gone viral on TikTok.

In the clip, uploaded by user @emiilyy_23, the seven-month-old dog walks into a room, only to spin around when she notices what appears to be another pooch.

The puppy then crouches into a defensive position, as she stares in shock at her own doppelganger and begins to growl in warning.

Her owner, laughing in the background, says: "That's you!"

The pooch continues to pounce and growl at the mirror, before darting forwards only to retreat in fear when her reflection copies the exact same move.

The German shepherd puppy was startled by her own reflection
The German shepherd puppy was startled by her own reflection

Eventually, she sniffs the glass and appears to realise there is no dog there, although she is presumably still baffled by the strange sight.

The video has been watched more than 1 million times and received 150,000 "likes" after her owner uploaded the video with the caption: "Just my 7mo German Shepard seeing herself in a mirror for the first time."

One delighted fan wrote: "Hilarious! She's like, get out of my house."

"I spilled my drink I laughed so hard at this," confessed another viewer.

A third commented: "Dogs are such goofballs! I love them so much."

Someone else wrote: "I laughed out loud at this! Animals are so funny."

Meanwhile, a few people saw the dog's behaviour as aggressive, but others said it was a normal reaction to finding what appears to be a threat in the home.

One person remarked: "This is literally as if an unknown dog had jumped through a window.

"Humans do this too when they first encounter a mirror."