Diesel vom Burgimwald, the German Shepherd who portrayed the titular K9 Rex on the series, "passed away" during production of season seven, according to Sherri Davis (pictured left with Diesel), the executive producer and dog owner for Shaftesbury's Hudson & Rex.
"He was diagnosed with late-stage cancer and unfortunately succumbed to the disease," Davis confirms to PEOPLE.
Davis was Diesel's trainer and the dog's devoted parent. She first met the dog in 2017 when Diesel was still a young dog. Davis was visiting a "reputable German Shepherd breeder" when she saw the dog peeking into a hallway.
"I asked the breeder, 'What's with that dog down there?' And he said, 'Oh, Dodo, that dog was returned. He's no good!'" Davis recalls of the day she met Diesel, adding, "But there was something special about Diesel. I ended up taking him home that day."
A few months after Davis, who has worked in animal training and rehabilitation for 30 years, introduced the pup to her menagerie of animals, the dog found stardom.
"The producers for Hudson & Rex came out to my facility for a camera test with my dogs. One of the producers looked at Diesel immediately and said, 'There’s Rex. Get to work!' They did a little demo reel, and he never left my side since that day. We were together 24-7," Davis explains.
For Diesel to be ready for the role, Davis had "two months" to take "a dog that had been returned to a breeder at a year and a half old" to the star of "the pilot of Hudson & Rex." The pair pulled it off, and for six seasons, Diesel's talents shone on the small screen, with Davis there by his side at every step.
"Diesel amassed a global fan base, and people have fallen in love with him on and off screen. He visited children in the hospital, FaceTimed elderly fans as a final wish, and touched the lives of everyone on set," Davis says about the dog's time on Hudson & Rex.
Diesel has also captured a large part of Davis' heart: "Diesel's personality is subconsciously one of the sweetest and kindest I've ever met. He's so sensitive to emotions. He's magical," she says.
The loss of her constant companion has understandably been difficult for Davis and she is grateful for the support of the cast and crew of Hudson & Rex during this challenging time.
"I shared Rex/Diesel with the world, but for me, he was part of my soul. He was with me 24-7 for seven years. He never left my side. I never went anywhere without that dog. So, you know, it's heartbreaking," Davis says, adding, "I am grateful to our dog team and am incredibly thankful to our excellent cast and crew because they have championed me through this sadness."
Diesel's legacy lives on through his nephews, Dillon and Dante, who have taken over his role as Rex on the show. Both dogs trained for two years before appearing in season 7, which is currently airing on Citytv in Canada.
