An animal protection group has accused the Petland Inc. pet store chain of scheming to sell sick puppies bred in filthy conditions to thousands of unsuspecting people.

Petland intentionally misled thousands of customers into believing the puppies came from the finest breeders and were healthy, the Humane Society of the United States said in a lawsuit against the company, which is based in Chillicothe, Ohio.

The group said it conducted an investigation showing that many of the puppies sold by Petland in its 131 U.S. stores were bred in mills in horrific conditions or through brokers such as The Hunte Corp., based in Goodman, Mo. Investigators for the Humane Society saw "puppies living in filthy, barren cages reeking of urine, with inadequate care and socialization," the complaint said.

The plaintiffs are seeking changes in how the puppies are bred and financial damages to help recover veterinary costs they say were associated with keeping their puppies alive. They also are seeking to stop what the lawsuit alleges are unfair and deceptive sales practices.