ALBUQUERQUE, N.M. Emaciated horses barely clinging to life at a New Mexico auction house, their last stop before a lengthy trip to a slaughterhouse south of the border, give credence to grim tales from around the Southwest.

People unable to afford the rising cost of hay, dumping their horses on the side of the road. Tens of thousands of wild horses roaming public and tribal lands, stripping drought-plagued landscapes and draining stock tanks.

As horse rescue operations struggle to keep up with a growing number of neglected, abused and starving animals, a Roswell, N.M., businessman has filed an application to open what would be the first horse slaughterhouse to operate in the United States in five years.

The proposal by Valley Meat Co. owner Rick De Los Santos has reignited emotional debates over what constitutes humane treatment of horses, and how best to control an exploding equine population. Perhaps the most divisive question of all is whether the noble, iconic animals that played a key role in the settling of much of America are livestock or pets.

“It's probably the most polarizing issue the horse industry has had to face in a long time,” said Ward Stutz, senior director of breed integrity at the American Quarter Horse Association in Amarillo, Texas, one of a number of livestock and horse groups that support a return to domestic slaughter.

“Let me just say it this way,” he said. “We believe it is the owner's right to determine what is in the best interest of their horses. We recognize that there is a lot of abandonment and neglect, therefore we believe that horse slaughter should be available.”

Many animal humane groups and public officials are outraged at the suggestion, including New Mexico Gov. Susana Martinez.

“A horse's companionship is a way of life for many people across New Mexico,” Martinez said after the proposal became public earlier this year. “We rely on them for work and bond with them through their loyalty. I believe creating a horse slaughter industry in New Mexico is wrong, and I am strongly opposed.”

Supporters of horse slaughter point to a June 2011 report from the federal Government Accountability Office that shows cases of horse abuse and abandonment on a steady rise since Congress effectively banned horse slaughter by cutting funding for USDA inspection programs in 2006. But a bill passed last year authorized the USDA to resume horse slaughterhouse inspections, prompting the application from De Los Santos. His cattle slaughter business dropped off as area ranchers sold their herds because of drought.

“What we see here will actually break your heart,” said Charles Graham, executive director of New Mexico Horse Rescue at Walkin’ N Circles Ranch and a supporter of humane horse slaughter in the United States.

“The problem in New Mexico is there is a lot of land. People get a horse, the wife loses her job, they keep the new car, the big TV, the cable service, and a horse in the backyard starving,” he said

In Colorado, the GAO report states, investigations for abuse and neglect increased more than 60 percent after horse slaughter was banned domestically, from 975 in 2005 to 1,588 in 2009. Although national data is lacking, the GAO report says California, Texas and Florida have also reported a rise in the number of abandoned horses since 2007.

The number of U.S. horses sent to other countries for slaughter has nearly tripled since domestic horse slaughter ceased. Last year, 68,429 horses were shipped to Mexico and 64,652 to Canada, according to USDA statistics compiled by the Equine Welfare Alliance, a nonprofit dedicated to ending horse slaughter. That compares to total exports of 37,884 in 2006.

In New Mexico, Randol Riley, a supervisor with the New Mexico Livestock Board, said he gets calls reporting suspected abuse every day. And he says abandonment is on the rise.

“Here lately it's gotten worse. They are dumping horses like crazy,” he said, as he delivered three horses a private landowner found abandoned without food or water on his property. The new arrivals brought the population at Walkin’ N Circles to 90 head, 30 above what the facilities and budget are meant to handle. The state's other eight licensed rescues are also above capacity, and have been for years.

The plight of some horses was captured recently on video posted on YouTube by the animal rights group Animal Angels. The video, which shows four horses unable to stand inside a pen at the Southwest Livestock Auction in Valencia, N.M., prompted a criminal probe by local and state officials of the sale yard, where many unwanted horse are bought and sold for slaughter in Mexico.

The Valencia County district attorney on Tuesday charged the auction's owner, Dennis Chavez, with 12 counts of misdemeanor and other animal cruelty charges related to the four horses, which had to be euthanized. Chavez did not immediately return calls from The Associated Press.

Debbie Coburn of Four Corners Equine Rescue in Farmington, N.M., says the case highlights the need to end horse slaughter, including in Mexico. Instead, she said, the horse industry needs to address the issue of population control.

“The slaughter pipeline is where the majority of abuse and neglect take place,” said Coburn. “To use slaughter as a way to get away with abuse and neglect is how I see it ... that's what slaughter is, a way for people to throw their trash under the carpet.”

Graham said opinions among horse lovers “are all over the board. ”

“What really bothers me is the hypocrisy. As soon as they cross the border we turn a blind eye. And those horses die a horrible death,” he said. “To say we can't regulate slaughter and make it humane ... we can. Everybody who opposes slaughter, tell me your solution to 130,000 unwanted horses every year.”

Graham said rules should be implemented for slaughter to make certain the horses are killed humanely, meaning instantly, taken care of on their way to slaughter by being fed and watered, with injuries treated. Most important, he said, the highly intelligent animals shouldn't see other animals being killed or placed in a position to smell blood.

Indeed, on a recent visit to the rescue operation east of Albuquerque, it was clear how in tune the horses are to other horses. As state livestock inspector Riley drove in with the three new arrivals, each of the some two dozen horses in nearby corrals stood completely focused on the trailer even before it passed through the gates.

In Roswell, De Los Santos said he is just trying to revamp a family business to meet demand. He said there is a healthy market for horse meat, which is consumed by humans in a number of countries in Asia, Europe and South America and is used in pet food. He said he followed all USDA instructions for converting his slaughter floor for horses, but has been told no action will be taken on his application this year because of the issue's volatility in an election year.

“The slaughter process is still going on, we are just not benefiting from it,” he said. “It's part of agriculture. Horses are livestock. They are still going to slaughter, but there is the stress of hauling them all the way down to Mexico.”

Coburn said she doesn't see it as livestock versus pet issue, but a “how do we approach this in the best interest of everyone.”

Still, she said there is no denying the animals are special.

“What about the magic of a kid and a horse,” she said. “It's indisputably there.”