This rambunctious German shepherd might look like a puppy, but he is 4 1/2 years old. Owing to a rare condition, he will remain small his entire life. The dog, Ranger, is generating an army of fans on social media for his unusual looks and funny antics, and his owner, Shelby Mayo, 20, a student nurse at Grand Canyon University in Phoenix, Arizona, is using the platform to help educate breeders about his condition. “We knew him from pretty much right when he was born,” Shelby told The Epoch Times. “We didn’t know about his dwarfism probably about until he was a year old.” Ranger’s diminished size owes to a condition known as pituitary dwarfism, but it means much more than a pint-sized frame and cute Instagram photos. Ranger also has a reduced life expectancy. “He won’t grow big like a regular German shepherd,” Shelby explained. “He has what’s called hypothyroidism … …