- “There'll be no living with him from now on.”
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. In one scene of the first film, Jock mentions to Lady of the "bygone days when he and his grandfather were tracking criminals through the swamps," indicating that he is from Louisiana. His Southern accent and way with manners further confirm his roots.
Eventually, Trusty's age caught 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.
Like a true Southern gentleman, Trusty is always courteous. He always refers to Lady as 'Miss Lady, Ma'am.' Unlike the more outspoken Jock, he never raises his voice or loses his temper, even when dealing with dogs like Tramp who he does not care for (in the first half of the film).
Trusty first appears at the beginning of the film where he is asleep, dreaming of his glory days of tracking down criminals in the swamps of Louisiana with his grandfather, Old Reliable. Jock mentions to Lady that poor Trusty has long lost his sense of smell. When Trusty finally awakens, he is delighted to see the new collar given to Lady and comments that she has grown up so fast.
Trusty later appears with Jock, as Lady is depressed at the fact that Jim Dear and Darling have not been giving the love and respect that she usually gains from them. They realize that Darling is having a baby and tries to explain with no luck until Jock does so. They briefly describe what a baby is and is interrupted by Tramp. Trusty tells Lady not to listen to Tramp's stories.
After Lady's heartwarming and heartbreaking adventure with Tramp, Trusty and Jock then appear as they visit her. Following this, Trusty is then seen feeling very guilty at the fact that he and Jock misjudged Tramp after he saved Jim Jr. from a vicious rat. To redeem themselves, Trusty and Jock rush to find the dogcatcher's wagon and save Tramp, where Jock realizes that Trusty never lost his sense of smell; in fact, Trusty's sense of smell is so acute that the rain concealing the trail helped him track it down. Trusty and Jock successfully stop the wagon, but Trusty was caught in the wheel, leaving him seriously injured, seemingly killed. However, on Christmas Day, it was shown that he survived with a broken leg and Trusty joins, Lady, Tramp, and their family for Christmas. Both he and Jock expressed admiration to the pups and to Tramp's new collar, like they did with Lady about hers in the beginning.
Trusty reappears in the sequel and first appears in the beginning as he and Jock watches Lady, Tramp, and their family stroll through the neighborhood. He and Jock later appears after Scamp has run 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 and Jock joins the group as they search for Scamp. Along the way, Trusty's sense of smell has seemingly failed him again, having sniffed out a lady's wig, six cats, three gophers, two rabbits, five flying pigs and a wildebeest before finally finding Scamp shortly after he escaped the pound. In the end, everyone is reunited once again.
Trusty made a cameo appearance in the debut episode of Walt Disney's Wonderful World of Color, Adventures in Colors and Shapes with a pack of other dogs including Jock and Pongo from One Hundred and One Dalmatians as they chase down Ludwig Von Drake for a steak.
Trusty appears in the film remake, voiced by Sam Elliott in the remake.
- Trusty's howling and his actions of doing so through the streets were given to Toby from The Great Mouse Detective. Also, his scene of almost scaring the dogcatcher was recycled in the film as well.
- It's ironic that Trusty lost his sense of smell, as bloodhounds are arguably the dog breed with the best sense of smell.
- Originally, Trusty was going to be killed by the dogcatcher's wagon when it accidentally toppled over and crushed him to death. However, Peggy Lee burst into tears when she saw it and pleaded for Disney to avoid another traumatic scene like in Bambi, so the animators had to revise the final scene so that Trusty would be alive on Christmas Day, with only a broken leg.
- Trusty is one of several bloodhounds from Disney's main canon, alongside Copper, Bruno, Towser, & Napoleon.
- Trusty's introduction is identical to that of Bruno, as they are both first seen whimpering, growling, and chasing something in their sleep.
- It is implied that Trusty knows the rat because when he heard Aunt Sarah scream, he said that he "should've known".