Through the SPCA she was able to follow through with prosecutions, using warranted inspectors.
"It was a full time job for me for 22 years and I travelled the length and breadth of New Zealand investigating complaints with horses and making things better for horses."
Mrs Shearer, who was based in Hamilton, opposite the Waikato Equestrian Centre, said many of the complaints came from concerned members of the public over what she describes as "passive neglect".
"A lot of people who didn't have any idea, thought it would be nice to own a pony. But horses cost money and they're a huge time consumer."
The neglect included overstocked horses, thin horses, fat horses, horses with not enough feed, horses that didn't have their hooves trimmed and with laminitis a foot disease than can cause lameness.
"The worse thing I always encounter is horses milling around paddocks with no grass and the owners have no money to feed them.
"Generally a lot of it is economic, and certainly recently there's been a big increase of horse owners who become unemployed or go on benefits and can't look after them and so you've got a major problem."
The 65-year-old, who became interested in horses almost 40 years ago when her daughter began riding, had also helped in ownership disputes.
In many cases of horse theft it often turned out the horse had been taken by a disgruntled joint owner after a partnership breakdown.
"It's quite often not horse problems, it's people problems and that's what you're dealing with."
In cases of severe neglect, when a horse was "too far gone" it has had to be euthanased under veterinary advice.
Some of the horses she rescued were thoroughbreds who initially didn't make it as racehorses.
"We've had a couple I can recall that have just been bags of bones, young, but they've come back and people have competed on them and they've done really well."
Animal cruelty legislation had tightened up, creating a good awareness of the issues, Mrs Shearer said. "Education is so important, for young people just to know how to treat animals in general, because there's a lot of animals out there that get a real bad deal."
Mrs Shearer said she had never walked away from a horse welfare issue.
She still planned to be involved with horse welfare and said sharing her knowledge was vitally important because often it was the same people who kept offending.
