The findings come from the Unwanted Horse Coalition, which commissioned the survey. The coalition is an alliance of equine organisations that joined together under the American Horse Council to educate the industry and public on the big issue of unwanted horses.

The coalition said 87pc of respondents said the issue is now "a big problem," compared with 22pc who believed that three years ago.

The coalition said respondents consider the economic recession to be a major contributor to the unwanted horse problem.

The closing of US horse slaughter facilities, changes in breed demand, indiscriminate breeding and high costs of euthanasia and carcase disposal were also cited as important reasons, the coalition said.

Regarding placement options for unwanted horses, the coalition said 63pc of equine rescue/retirement facilities polled reported that they are at or near capacity and turn away 38pc of horses brought to them.

Capacity is clearly the issue, the coalition said, in that as many horses stay for life at the facilities as are adopted out.

The survey was conducted by an independent market research company that contacted more than 23,000 horse owners and equine industry stakeholders, as well as non-horse owners.

In a related development, the National Congress of American Indians (NCAI) has passed a resolution supporting the reopening of the US horse plants and urging an end to federal government interference in the ability of tribes to manage horses on tribal lands.

* The survey is available at www.unwantedhorsecoaltion.org.