Two of her horses, Gucci and Rolex, were found to have been treated with pain relieving substances four days before the HFRK Grand Prix, in Helsingborg in February.
The horses were treated with the prescription drugs flunixin and Adequanin. One horse was treated with both. Flunixin is a non-steroidal anti-inflammatory drug (NSAID) with analgesic and anti-rheumatic properties. Adequan is a glucosamine based product which stimulates cartilage repair and reverses traumatic joint dysfunction, according to the manufacturer. Both are on the Swedish Federation's list of banned substances.
Kroon appealed to the RIN, the national board of athletics, which decided to reverse the Swedish Equestrian Federation's decision.
Swedish Equestrian Federation President Bo Helander has expressed his disappointment at the decision.
"Such a case completely contradicts our values. The verdict is so surprising that it requires a lot of analysis before we can comment further," Helander said.
"For us, horse welfare and fair play are paramount and we have all worked for years to have a clean sport where animal protection and competition on fair terms is equally important."
RIN said that it had referred to WADA (World Anti Doping Agency) rules in the case, and that FEI regulations apply.
"If so, we need to ask WADA to review its regulations and there is also reason to ask FEI modify their rules," Helander said.
"We have worked hard for a clean sport, Sweden was driving force in the process 20 years ago that led to the zero tolerance limit for phenylbutazone in competition, and we will not give up work for a clean sport.
"We will never accept cheating, a breach of animal welfare law or that the horse does not come first," Helander said.
He said that over the next few days, the Swedish Equestrian Federation would contact WADA, and the FEI's Clean Sport Commission, chaired by Professor Arne Ljungqvist, to discuss modifications that are needed to have consistent rules in equestrian sport.