David Gallagher Says “7th Heaven” Episode Where Dog Happy Gets Hit by a Car 'Was Really Heavy for Me'

Gallagher met up with costars Catherine Hicks, Beverley Mitchell, Mackenzie Rosman and Barry Watson at 90s Con Florida in Daytona Beach, Fla. on Sunday, Sept. 15

The stars of 7th Heaven saw fans’ happy faces smiling back at them at 90s Con Florida.

David Gallagher, Catherine Hicks, Beverley Mitchell, Mackenzie Rosman and Barry Watson gathered at the Ocean Center in Daytona Beach, Fla. on Sunday, Sept. 15, to look back on their hit show in a panel moderated by PEOPLE TV Staff Editor Dory Jackson. 7th Heaven ran for 11 seasons from 1996-2007 and followed a reverend and his wife navigating the ups and downs of raising seven children of various ages.

One important cast member who didn't attend 90s Con Florida: the Camdens' family dog Happy. But the stars remembered the beloved pup, who died in 2010 at age 15.

"We all loved Happy," Mitchell, 43, gushed.

Rosman, 34, chimed in, "She was a very good dog."

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Mitchell revealed that show creator Brenda Hampton wrote the role of Happy specifically for the rescue pup. "Brenda saw Happy, she loved Happy, wrote the show for Happy," the actress said with a laugh.

Gallagher, 39, revealed that Happy didn't exactly love life on set, though.

"Happy was scared of the crew members on the set because there’s about 100 people you never see constantly around us why we are filming," he said. "Every time we did a shot, everyone has to swap out, the crew runs in, Happy would get nervous about it. But because me and Happy worked together every day, she would stick with me. I would often take Happy with me as we cleared out and we’d go back to the trainers and take a break."

Because of his close bond with Happy, Gallagher found filming the episode where she got hit by a car in season 1 (and survived) to be especially tough.

"I just remember coming home and going to bed after doing the scene where Happy was hit by a car. That episode was really heavy for me," Gallagher said. "There were certain episodes that stick out that require you to give it your best, honest shot, and try to connect with the emotions of it. And you would drive home from work that day and feel destroyed. That stuff’s the hardest work. If you get it right, it’s the work you’re most proud of."

Rosman shared a challenge of her own that she experienced while filming 7th Heaven at a young age. "They gave me a flute because Ruthie was supposed to play a flute," she recalled. "And I was proud of myself for getting it to make noise."

Hicks, who played Camden matriarch Annie, felt proud of her on-screen daughter for learning to play the her flute, too.

"She was 6 years old!" Hicks, 73, said. "Sometimes I feel I overlooked your performances. She was tiny."

Hicks had a 4-year-old child at home when she started filming 7th Heaven, and she told the crowd at 90s Con Florida that she sometimes carried guilt about spending more time being a TV mom than a real one to daughter Catie. "I was sort of rude and not friendly to these children because I was always feeling guilty that I wasn’t home," Hicks claimed. "So I wasn’t nice to them."

However, Mitchell said, "That was not true. I thought you were lovely. I’ve always had a great relationship with you and I never thought you were mean to us. I thought you were busy and you had to get to Catie."

Mitchell and Rosman also talked on Sunday, Sept. 15, about why they chose to leave the show after season 10.

"I was ready to do something else with my life, experience being a normal kid in a school with other children my age and we weren’t children anymore," Rosman said. "I wanted to be a senior at a high school with other seniors there. That was my main hesitation, I wanted to give myself a normal childhood experience."

Mitchell, too, wanted a typical school experience and attended Loyola Marymount University. The mom of three said she wanted to "be normal kid and live in the dorms," but, "that was a bad idea."

"I became the head mother for the entire dorm," Mitchell explained. "That only lasted a year. I decided to go back to work."

Gallagher reflected on stepping back from the show when he got into University of Southern California.

"When I got into USC film school, I had told the production that I could make some time, schedule your own classes in college and do a four day work, one day on set," he said. "But I had to do full time USC, not full time set. That’s why we had that recap episode where I had stepped out and then they hit me up at the end of that season my freshman year, 'Will you come back to do the finale, just one day?' 'Sure, I’m okay with that.' Then we got picked up again, 'Hey, crazy idea, think we could do one day a week where you come in and do school full time?' Then through those seasons, I was kinda part time."

The show's 11th and final season coincided with Gallagher's senior year of college. "I just kinda wanted to do my senior year and be at school and be present, keep that experience on its own," Gallagher said. "So I wasn’t there for the 11th season. I just wanted to be a college student and see what that was like."

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In April, Gallagher, Mitchell and Rosman announced a rewatch podcast, Catching Up with the Camdens.

"It’s been over a decade since I’ve revisited my life on the show," Gallagher said in a statement shared with PEOPLE. "The best part about doing it this way is that it gives us all a reason to reconnect with each other. It feels great to spend time with the family again."

Mitchell shared the overwhelmingly positive reaction to the cast’s reunion at 90s Con in Connecticut in March encouraged her and her former on-screen siblings to team up for the podcast.

"Growing up as an only child, these people have always been my family. After 90s Con it was clear that there is still a lot of love for the show among the fans, so why not get the gang back together," Mitchell said. "And honestly, it's like we never left. We truly are family and I am thrilled to revisit some of my most cherished and sometimes embarrassing memories."

Rosman also said at the time that working with Gallagher and Rosman again feels natural.

“Reconnecting with these people whom I love so dearly and have shared literally my entire childhood with, feels like the most natural thing on Earth,” she said.

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Catching Up with the Camdens launched in June and featured a mini reunion with Watson, 50, when they spoke with him in a two-part episode that aired in July and August. Watson, who played the oldest brother on the show, recalled struggling financially before 7th Heaven premiered.

"I remember having to borrow like, money from my manager at the time because I couldn't pay my bills until I got that first episode paycheck," Watson told Mitchell, Gallagher and Rosman on the July 22 episode of Catching Up with the Camdens. "And I remember, you know, Mary still like going, 'I don't know why you wanted to do this.'"

Along with getting the Camden clan back together again, 90s Con Florida also saw the casts of Beverly Hills, 90210, Charmed, Full House, Melrose Place and Sabrina the Teenage Witch reunite throughout the weekend.

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90s Con Florida is occurring through Sunday, Sept. 15, at the Ocean Center in Daytona Beach, Fla.

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