Diogee is a dog who is very loyal to his owner Milo Murphy; so much that he gets out of the house just to reunite with Milo at random times of the day, usually during Milo's predicaments. Diogee will casually appear to save Milo and his friends from any situation, this is used as a running gag in many episodes. Milo usually tells him to go home, and sometimes says "He's not supposed to be..." which can be said in any place where Milo usually is. He always knows the way home and the way to Milo. He doesn't always appear to save Milo, he sometimes appear just to stay with him, even though this means he doesn't obey to his owner.
He likes the film The Dog Door Bone Files, but he gets annoyed if a larger dog sits in front of him during the film. He is very friendly like most well socialized dogs.
Diogee has cream-colored fur with small brown spots right over his mouth and a large, round, brown nose, floppy ears, and a brown "stain" over his back.
Diogee's most prominent relationship is with Milo and his best friends, Melissa and Zack. He always knows how to get to Milo.
The image gallery for "Diogee" may be viewed here.
His name's pronunciation is phonetically based off the spelling of the word "dog".
Dee Bradley Baker, who provides sound effects for Diogee, also did vocal effects on Phineas and Ferb, most notably performing the part of Perry the Platypus/Agent P.
His role in the show also mirrors Perry's. Perry is a secret agent with human-level thinking, Diogee is a normal pet with normal dog behavior. While Perry usually hides from Phineas and Ferb when fighting against Dr. Doofenshmirtz, Diogee usually joins Milo's antics.
In Missing Milo, Diogee's full name is revealed to be "Diogee Ex Machina Murphy".