Though the cost of treating those injuries had gone down from $12.1 million in 2009 to $11.3 million last year, one serious injury case could skew those figures, ACC spokesman Glenn Donovan said.
ACC considered a serious injury to include a serious spinal or moderate to severe brain injury.
These injuries generated high costs to cover life-changing circumstances such as home alterations if a person became wheelchair bound.
Mr Donovan said most of the claims were for minor injuries such as soft tissue damage.
"By and large the injuries aren't major but it only takes one or two serious injuries to really skew the costs."
Equestrian Sports New Zealand chief executive Jim Ellis said the organisation had very strict safety regulations.
"There are clear risks in the sport ... but it's also a very controlled environment."
Mr Ellis said the high level of rider injuries and deaths in the late 1990s could have put an end to the sport, which includes eventing, dressage, cross-country and showjumping. But there had been an "incredible toughening" of safety standards.
That includes the use of back protectors and changes around helmet wearing for dressage riders, with the exception of elite competitors, where once top hats were worn.
Riders must also wear medical arm bands with blood type and other details in case of a severe injury.
Cross-country course safety was also paramount and massive design changes had been implemented to prevent rotational falls, where the horse falls on a rider. Air vests, which inflate when a rider falls, were controversial because some riders insisted they prevented people from tucking and rolling.
Mr Ellis said the death of well-known French eventing rider Bruno Bouvier in Portugal in March had shocked the industry and intensified safety awareness.
Other preventative measures included a big move to introduce frangible pins on cross-country fences.
When a horse hits the fence the brittle pin snaps, allowing the log to break away, which minimises the chances of the horse and rider falling badly.
He said horse accidents were more formally investigated now and reported at an international level.
"Certainly in eventing the statistics have shown just huge improvements over the 10 years, but clearly if riders are still dying around the world then there's more to be done."
He said when "you're riding a 600kg animal at some speed" that it's difficult to say it's "ever going to be perfectly safe".
ACC lists its highest claim sports as rugby union and league, soccer and netball.
The organisation, in conjunction with the New Zealand Pony Clubs Association (NZPCA), has developed a DVD and accompanying booklet aimed at promoting safe horse riding and horse handling practices among young riders to help curb the number of accidents.
Bumps and breaks part of life in saddle
Diane Norton was riding someone else's horse in a hunt when the excited animal bucked her off.
Miss Norton, 50, smashed into the saddle several times before landing heavily on her tailbone, breaking her left seat bone and buckling her sacrum bone.
She couldn't get off the ground but fortunately a friend on the hunt, an ambulance officer, tended to her within seconds.
The Cambridge woman was flown by the Westpac Waikato Air Ambulance to Waikato Hospital, assessed by physiotherapists and had a CT scan which showed the injuries.
She was admitted for two nights before being discharged on crutches under strict instruction to rest for 12 weeks.
While she's off work from breaking horses in, ACC will pay up to 80 per cent of her income.
Having worked with horses all her life, it's not the first time Miss Norton has been injured by one of the animals.
Two years ago she was front-footed and kicked in the pelvis.
"That fractured my pelvis, broke the transverse processes of seven vertebrae in my lower back and dislodged one in my neck. And then I ended up with shingles from the nerve damage."
Years before that she was bucked off while riding track work and a protective vest which all track riders must wear prevented her from being able to "tuck and roll".
She always wears a helmet and on hunts, where it's all about etiquette, she wears a jacket and long leather boots for protection.
There had been lots of other little accidents over the years.
"Apparently my ACC file is a great big thing like that."
But that was nothing compared to friends and colleagues who had either been paralysed or killed during her time in the horse racing industry.
However, Miss Norton said her fall two weeks ago was "just one of those things" and she couldn't wait to get back in the saddle.
"It's not what I'd call a serious accident. It's just like if you play rugby or netball, or anything, you're going to get hurt. It's not really that dangerous. Riding a motorbike or in cars and trucks is more of a risk than riding a horse."
ACC claims
For horse-riding injuries
2012: 6749
2011: 6095
2010: 5917
2009: 6301
