Butt, from West Melton, won her 100th race in New Zealand when she steered Imran Khan to victory in race 3.
Horton trained her first winner two races later, when Bettors Atom prevailed. It vindicated her decision to try her hand at training after more than a decade out of racing.
The Makarewa trainer got her start in harness racing with former leading Southland horseman Bud Baynes, then took a break from the sector.
"I worked for Bud Baynes back in the 1980s, but I left it all behind and went farming," Horton said.
"Now I am back training and I also give Craig Ferguson a hand."
Bettors Atom did not win like a horse who had taken 43 starts to win a race when Ferguson steered her to victory.
The 6yr-old worked hard off the mobile and was trapped three wide into the first bend. She continued to work around the field until reaching the lead at the 1400m, then
cleared out for a stylish two-length victory.
"She tries hard and that is her thing, but she has never been in front, so that surprised me a bit," Horton said.
Ferguson also won race 9 with Nomorechange, a horse he trains and drive.
Butt's 100th win was with the Amber Hoffman-trained Imran Khan. It came on the same track where Butt scored her first driving win, five and a-half years ago, with Saveapatrol.
Butt gave Imran Khan an economical run in a chaotic affair before launching him for a sustained finish from the 400m.
The reinswoman then wasted no time in notching up win 101 when she steered Jungle Gem to victory in race 4.
Trainer-driver Jonny Cox, Butt's fiance, made it a hat-trick of wins for the couple when Lightfoot Lady won the next race.
It may have only taken one start on his home track for Havehorsewilltravel to show trainer Darryn Simpson he had found his next good trotter.
The 3yr-old looked like a possible replacement for Simpson's former stable star Pres The Belle when he produced a crushing win in maiden company over 2200m.
The Angus Hall trotter worked hard and sat parked for the last lap then powered away from his rivals to score by three lengths.
Havehorsewilltravel's win was an all-Dunedin affair. The trotter is raced by Garry Clarke and was bred by Darryl and Anne Trainor.
The victory also continued the hot form of the progeny of mare Winfield Invasion.
Havehorsewilltravel's older half-brother, Mclovin, has been a trotting sensation since joining Andy Gath's Victorian stable.
The 7yr-old has won eight of his 13 starts and produced two group-3 victories this month.