SAN DIEGO -- The former executive director of the North County Humane Society pleaded guilty Thursday to fraudulently obtaining 3,600 Vicodin tablets by using the federal drug registration numbers of three veterinarians.

Stacy Steel was ordered by Vista Superior Court Judge Daniel Goldstein to enter a drug treatment program, pay a $500 fine and submit to searches by law enforcement at any time.

The charge will be dismissed if Steel, 37, successfully completes the treatment program, the judge said.

The defendant ran the Humane Society chapter for three years before resigning her $95,000-a-year job on March 25.

Deputy District Attorney Richard Madruga said Steel obtained the tablets -- officially called hydrocodone -- between Aug. 22, 2005, and Feb. 9 of this year.

The offense was serious, but the plea arrangement for the Encinitas resident was "completely fair," Madruga said.

"There's no evidence that she was selling the pills, or taking money from the Humane Society to buy the pills, and no evidence that the animals were endangered," the prosecutor said.

The North County Humane Society, as a licensed handler of veterinary drugs, is monitored by the federal Drug Enforcement Administration. It runs a shelter in Oceanside and provides animal control services under contract with the cities of Oceanside and Vista.

Madruga said the case showed a "lack of oversight" in how the agency orders narcotics, and he expressed hope that procedures would be revised.