As my grandpappy Old Reliable used to say... uh...Don't recollect if I've ever mentioned Old Reliable before. (Jock: Aye, you have, laddie.)
Have I ever told you girls about the time I saved your father from certain death?
~ Trusty to Annette, Collette and Danielle
Trusty is the tetartagonist in Lady and the Tramp, and a supporting character in the sequel. He is an elderly, somewhat senile bloodhound with a weakened sense of smell. At the end of the movie, he seems to have died from having a wagon fall on him, but he only had a broken leg.
Lady and the Tramp
Trusty is the neighbor of Lady, and possibly the oldest dog in the film. According to Jock and himself, he was once a service dog working alongside his grandfather, the esteemed Old Reliable, to track down and capture criminals before eventually having his age catch up to him, which is when he supposedly lost his sense of smell for a number of years. Though Trusty firmly believes his strong sense of smell remains intact, Jock believes otherwise (though he refuses to admit it, not wanting to hurt Trusty's feelings).
Now retired, Trusty spends his days alongside his best friends, Jock and Lady, who hold a strong kinship with the old dog.
Trusty can usually seem absentminded and a little clumsy, but is a loyal, sweet and respectful friend to Lady and everyone else. He has a large way with manners, referring to Lady as "Miss Lady, ma'am." He can also be a blabbermouth, and regularly connects a story or topic to a piece of advice given to him from Old Reliable, with a statement going as followed: "As my grandpappy Old Reliable used to say, uh... Don't recollect if I've ever mentioned Old Reliable before," to which his friends would reply by stating he has.
At the very end when Trusty is about to tell it to Lady and Tramp's puppies, he realizes that he's completely forgotten what Old Reliable said to him now (as such, we, the audience, never actually learn what the advice was).
Lady and the Tramp II: Scamp's Adventure
Trusty reappears in the sequel and first appears in the beginning as he watches Lady, Tramp, and their family stroll through the neighborhood. He later appears after Scamp has ran away. Annette, Collette and Danielle bring the news and that's when Trusty brought back one of his old stories and mentioned the time he saved Tramp. Trusty joins the group as they search for Scamp. In the end, everyone is reunited once again.
Oliver and Company
Trusty made a cameo appearance with Jock and Peg in Oliver & Company during Dodger's song "Why Should I Worried"
Trusty made a cameo appearance in the debut episode of Walt Disney's Wonderful World of Color, Adventures in Colors and Shape .
House of Mouse
Trusty appears in several cameos on House of Mouse In " Pluto Saves the Day", he was part of the all-dog band alongside Jock and several other dogs from Disney animated films.