Ranger the German Shepherd is two-years-old, but you wouldn't be able to tell just by looking at him.
That's because the adorable dog has a very rare condition which makes him look like a puppy, despite being an adult.
Ranger, who lives in Phoenix, Arizona, with his guardian Shelby Mayo, was diagnosed with Pituitary Dwarfism after contracting a parasite called Giardia.
After recovering, his owners noticed that the pooch wasn't growing at the same rate as other dogs of his breed.
So they took him to the vet, where they discovered that he is stuck in perpetual puppy-hood.
While Ranger's condition may make him look cute, the poor pup has experienced several health issues in the past as a result, including shedding fur and flaky skin.
Despite this, the little dog has never let anything hold him back and is now happy and healthy - and enjoys a lot of attention from adoring fans on his Instagram account.
His owner, Shelby, said: "When we originally got Ranger from the breeder, he was smaller than all his other littermates, but we figured that was because he had a parasite .
"At the same time, we also discovered that Ranger had a large infection on his neck.
"We were eventually able to get the infection under control, fast forward a few months later we were finally able to get rid of Giardia."
She continued: "During this time Ranger remained very small, the vet had suspected that he may have Pituitary Dwarfism, a genetic mutation. But we were still sceptical as the condition is very rare.
"Over time Ranger still did not get much bigger and at this point we are certain he has the condition."
Shelby goes on to say she believes Ranger's genetic defect was caused during breeding.
"Ranger's litter was the first litter that our breeder had bred those two specific dogs together," she explains.
"We believe this was the cause of the genetic defect and a responsible breeder will not breed the two dogs together again."
She added: "He's healthy and happy as can be as of now and loves jumping around and playing with his ball and squeaky toys with his two sisters Hazel and Jessie."
Recently another cute pup also hit the headlines - because he had a tail growing on his head.
Narwhal was dubbed a because of his unusual defect.
The puppy was found abandoned in the US and taken to a Missouri-based rescue centre, where he quickly found fame online after videos of him were uploaded to Facebook .
Fans fell in love with the furry creature, but were rather disappointed to discover the extra tail didn't wag when he was excited.
