There are now just over 80 equine masseurs registered in Britain, with therapists required to first complete a massage course for humans before treating horses.
Once in the profession it's no easy ride, as each therapist requires permission from a vet before starting work.
As an equine masseur, it's essential to know the inner workings of an animal unable to vocalize what it is feeling -- making the anatomy paintings an important point of reference.
But the fine art of painting horses isn't all science based -- Rossa also decorates thoroughbreds purely for aesthetic value.
Earlier this month she painted a racehorse from neck to hoof in an intricate Christmas jumper, as part of The Jockey Club's online advent calendar.
For the photoshoot, 17-time champion jockey, Tony ''AP" McCoy donned a matching festive jumper as the pair leaped over a golden hedge laden with presents.
It wasn't the first time Rossa had used a horse as canvas, also painting a thoroughbred in the Union Jack as part of a special shoot for July's Barbury International Horse Trials in Britain.
Eventing competitor Laura Collett was pictured riding the remarkable painted horse jumping over a mini Stonehenge obstacle course.
It took Rossa more than five hours to paint the gray horse, using brown sticky tape to create the straight lines of the flag. "The horses seemed to quite enjoy it -- some just love the attention and being paraded around," she said.
With their insides vividly on display, these thoroughbreds are no oil paintings. But their eye-catching outfits may have proven picture perfect for training therapists the fine art of massage.