GOP presidential hopeful Mitt Romney and his wife have put their money behind a horse, and the guy who rides it.

According to a new financial disclosure form filed by the former Massachusetts governor, Romney’s wife, Ann, earned $15,000 to $50,000 since the beginning of 2010 in interest on a loan to a horse farm in California called the Acres. According to a spokesman for the campaign, the item is a personal loan of more than $250,000 that Romney’s wife made to the family’s horse trainer.

Romney filed his original disclosure form in August identifying assets worth at least $85 million. Like Members of Congress, candidates file forms disclosing the value of assets in broad ranges; because some categories of value have no maximum (such as spousal assets worth “over $1 million”), Roll Call only tabulates the minimum values.

At the end of September, Romney filed a one-page amendment to his disclosure form, noting an asset that had not previously been listed.

The asset is a loan valued at $250,000 to $500,000 to a firm called ACR Enterprises in Moorpark, Calif.

ACR Enterprises operates the Acres, a horse-training facility in a sport called dressage, which is a competitive discipline of steps and movements by the horse, a kind of gymnastics sometimes called horse ballet.

Ann Romney and two other women own a dressage horse named Rafalca, which is ridden in competition by Jan Ebeling, the owner of the Acres. The horse and rider have done well — in March, Ebeling and Rafalca won the California Dressage Affaire Grand Prix, according to a publication called Dressage News.

The loan is apparently to Ebeling, though Ebeling and his wife did not respond to emails and phone calls from Roll Call.

The Acres website shows a variety of spectacular horse country vistas and lists services ranging from boarding to horse sales to rider training. The site indicates that Ebeling travels the country holding dressage training clinics.

The Romneys are well-known on the dressage circuit.

The online publication DressageDaily.com described Rafalca and Ebeling’s prize-winning performance at the 2010 national dressage championships in August of that year and explained that both Romneys are active in supporting the horse. The publication said Mitt Romney “also plays a role on the Rafalca team, albeit a more hidden one,” and quoted Ebeling as saying, “He really enjoys the horses, but then, what choice does he have with a horse crazy wife.”

According to DressageDaily.com, “It was actually Mitt Romney who picked the freestyle music” for Rafalca’s August 2010 routine, “which comes from the soundtrack of the film The Mission.”

Ann Romney is also part-owner with Ebeling’s wife of Rob Rom Enterprises LLC, a California company that “owns horses,” the candidate’s disclosure form shows, though the couple reports no income from the corporate entity. The value of Rob Rom is listed as $250,000 to $500,000.

Presidential candidates file their financial disclosure forms with the Federal Election Commission, which reviews the forms then submits them to the Office of Government Ethics. The OGE does a more thorough investigation of the forms and then certifies them as accurate and makes them public. To date, Rep. Ron Paul (Texas) is the only major GOP presidential candidates whose form has been certified by the OGE, according to its website.

The FEC submitted Romney’s amendment to the OGE on Thursday, saying the loan was “inadvertently omitted” from his original filing.