Authorities have found more than 20 dead horses on a farm in West Virginia.

The West Virginia Department of Agriculture says it has activated its homeland security incident management team to assess the situation at the property in Greenbrier County.

Local reports indicate up to 26 horses have been found dead on the property, thought to be about 300 acres, since a tipoff to county officials on Wednesday.

A feed and grain store is just a few hundred metres from the property in Crawley, where the dead animals were found.

West Virginia's agriculture commissioner, Gus Douglass, said his department had the duty to ensure the carcasses were disposed of properly to protect the environment and the health of other animals.

He said his team left the department's headquarters at Guthrie early on Thursday afternoon local time and would report back once they assess the situation.

He said he was disturbed by the discovery.

"It seems we're seeing more of these incidents in recent years - particularly with horses - and I find that very distressing.

"Farmers have a moral obligation to care for their animals, and the vast majority of them do so. But there are a few that, for whatever reason, fall short of those responsibilities."

While the agriculture department has broad authority when it comes to controlling infectious diseases in farm animals, state law gives county sheriffs or their designees authority over animal welfare issues.

"Some people believe that the Department of Agriculture is responsible for the welfare of farm animals, but that's simply not the case.

"If we receive a report of distressed animals, we can enter a farm to see if the cause is disease related. If not, that's where our authority ends," said

One report from West Virginia suggested a law enforcement official visiting the property saw 14 dead horses as he headed up the old road to an abandoned farmhouse on the property.

A man is under investigation over the treatment of the horses and faces two counts of midemeanour animal cruelty, a report suggests.

Further reports indicate the man at the centre of the investigation has interests in other properties, which are also being checked.