They weren't Amelita Donald's horses--they had been spared--but the theft of three show-quality equines from the Dallas stables where her quarter horse is boarded sent Donald on a months-long journey last year through the often tawdry world of horse trading.

"The police wouldn't do anything for us and neither would the sheriff," she said. "We were told we'd have to find our own leads."

The victims of the theft banded together and hired private investigators. Donald threw herself into the search, which took her to slaughter plants and horse auctions where she said she encountered unbelievable wretchedness.

"You see the animals in these horrible conditions in the plants, standing in manure, with cuts and bruises and broken legs, with banged-up heads and their eyeballs dangling out," she said.

Her first impulse was to blame the animals' condition on the slaughterhouses, where horses are killed and processed for human consumption overseas. But Donald soon learned that the suffering began before the animals reached the killing pens.

From auction to slaughter, the journey taken by more than 300,000 horses yearly in the United States is needlessly filled with suffering, according to animal-rights activists, horse lovers and Humane Society officials familiar with the issue.

Ursula Liakos, a Northern California horse breeder and activist, says thousands of horses are mistreated and many die while being transported cross-country to slaughterhouses.

Most of the horses are bought at thousands of auctions held across the country. They make the trip to slaughter in overcrowded, low-roofed, double-decker trailers built for cattle. Such conveyances are also routinely used by ranchers, but critics say rides to the far-flung slaughterhouses sometimes cover thousands of miles. Horses cannot stand for long periods in double-decker trailers without suffering gashes, critics of the system say.

Defenders of the slaughter industry say it performs a service by humanely eliminating unwanted horses that otherwise might be neglected or mistreated by their owners. But critics say many animals arrive at the slaughterhouses not only with deep cuts but so starved and dehydrated that they can hardly stand.

Because there are no slaughterhouses in California for processing horse meat for human consumption, most California horses are transported to Texas, where there are four such plants in operation.