Delgado is a police dog who was once a member of the police force and was after a Doberman Pinscher named El Diablo. He lost his sense of smell after he and his former partner were ambushed by Diablo. Unable to help his injured partner, Delgado got kicked out of the force.
Delgado meets Chloe after he rescues her from a dogfight with Diablo. She thanks Delgado for saving her and asks him if he could help her find her way back to Beverly Hills. Delgado refuses at first, but after Chloe insists that she was dognapped and being pursued by Diablo, the police dog reluctantly helps her by keeping her from being detected.
Along the way, Chloe constantly pesters Delgado by asking him agitating questions. Later, while Delgado was asking for help from one of his German Shepherd friends, Chloe gets tricked by a rat named Manuel and an iguana named Chico, who talk her into giving them her diamond collar. When Delgado finds out, he quickly becomes furious with her because that collar was evidence to where she lived.
When Chloe and Delgado get lost in a desert, they are suddenly ambushed by three mountain lions. Delgado tries to fight them off, but he and Chloe are rescued by a large pack of stray Chihuahuas led by Montezuma. Chloe and Delgado then stay for a short time at the Chihuahua pack's birthplace.
Sometime later, the same rat and iguana from before help Delgado by presenting him with Chloe's collar. Delgado sniffs it several times, gets his sense of smell back, and goes to find Chloe. He eventually finds Diablo and defeats him by pinning him to the ground, although Diablo manages to slip away. Delgado becomes a member of the police force again and bids Chloe farewell before he leaves with his new partner.
Delgado reappears in the second film. He participates in the dog fashion show to win a large cash prize for Papi and Chloe's family to save Sam and Rachel's family home, although he is the first one to be disqualified. His main role is that he finds his two sons Alberto and Antonio that he had regretfully abandoned as puppies at a police station, due to an incident in the past. Later, after helping capture the bank robbers, Chloe and her family eventually explain to Delgado's sons why he did it, and they accept this from them and their father, thus earning him a place in Beverly Hills in the L.A. force for a while, and giving him and his sons more time to catch up a little.
Delgato has a small role in the third film. He shows up at the hotel garden that was vandalized by accident, listening to Papi about his plan to expose Jenny for her evil acts. After Papi and Pedro make her trip and fall in a puddle of peanut butter, Delgado is seen dangling Mr. Montague from a tree. He then drags Oscar into a police car and is not seen afterwards.
- The dog that acted for him is named Sam.
- Delgado is Spanish for "thin."