Almost 500 captive deer and elk have escaped from Minnesota farms over the past five years, and 134 were never recaptured or killed.

So far this year, 17 deer have escaped, and officials are still searching for many of those.

The escapes fuel concern that a captive animal infected with a disease such as chronic wasting disease (CWD) could spread it to the state's wild deer herd. There are 583 deer and elk farms in Minnesota, holding about 15,000 animals. Since 2002, CWD has been confirmed on four farms, and herds there were killed. This year, the first confirmed case of the fatal brain disease in a Minnesota wild deer was found near Pine Island -- where a captive elk farm was found in 2009 to be infected with CWD.

State officials with the Board of Animal Health, which oversees the deer and elk farms, and the Department of Natural Resources say there is no firm evidence the elk herd, since destroyed, is responsible for infecting that deer.

But given the proximity of the cases, suspicion remains high. And others say the continued escape of captive animals is problematic.

"It's a loose cannon, and unfortunately it has the potential of threatening our entire wild deer herd," said Mark Johnson, executive director of the Minnesota Deer Hunters Association. He only recently learned that 109 deer and elk escaped in 32 incidents in 2010, and 24 of those animals never were recovered.

"The escapes themselves are startling and worrisome, but the two dozen not accounted for are a real concern," he said.

Dr. Paul Anderson, an assistant director at the Board of Animal Health, said the escapes are unacceptable.

"We've talked to the industry people and we all agree those numbers are too high," Anderson said. "We and the producers need to do a better job. We're going to increase our enforcement in 2011."

But he said the risk to the wild deer herd is minimal. Deer and elk generally die within three years of exposure to CWD, and 551 of the 583 Minnesota farms have had CWD surveillance for three or more years.

"We're very confident those farms don't have CWD," he said. As for the other 32 farms, "we don't think they have CWD either, but our confidence levels are not as good. We're pushing them."

The law requires farmers to maintain 8-foot fences, but most of the escapes are caused by human error, Anderson said. "They didn't close a gate or didn't get it shut right," he said.

Captive deer and elk brought into the state must come from herds that have been CWD-monitored for at least three years. Anderson said 184 animals were shipped here in the past year, and farmers exported 1,200 outstate.

The DNR is hoping the lone wild deer that tested positive for CWD is an aberration. Officials have long said CWD is potentially devastating to the state's wild deer herd. The DNR is killing 900 deer near Pine Island to determine if other deer might have the disease. So far, all have tested negative. Since 2002, the agency has tested more than 32,000 hunter-harvested deer, elk and moose.

While the Board of Animal Health licenses and oversees the deer and elk farms, the DNR is responsible for animals that have escaped for more than 24 hours. Escaped deer and elk can keep both DNR conservation officers and wildlife managers busy.

Tim Marion, an assistant area wildlife manager in Cambridge, has 38 deer and elk farms in his four-county work area, which includes Isanti, Chisago, Mille Lacs and Kanabec counties. Since last August, he's had 21 animals escape from four farms. Dogs broke into two pens, a tree fell on a fence in a third and another owner said someone opened a gate while he was away.

Four of those deer were shot and seven recaptured. Ten remain unaccounted for. Finding them can be difficult. Of nine deer that escaped from a farm near Mora, officials shot one two miles away, another four miles away and a third 8.5 miles from the farm. All were reported by people who spotted the animals at recreational deer feeders because they had tags in one ear, as required by law.

"There's no way we would have gotten any of these deer without the landowners helping us," Marion said.

But he has another problem.

"Three of those deer out there have no tags in the ear," he said. Will he find them?

"All I can say is we're trying," he said.

DNR conservation officer Jim Guida of Nisswa knows firsthand about escaped deer. He was bow hunting last fall near home when he shot a 10-point buck. Later, he was stunned to find a tag in its left ear.

"I thought it might be a [wild] research deer tagged at Camp Ripley," Guida said.

Wrong. It had escaped from a farm a year earlier.