A dozen kennels in Pennsylvania are among the 100 listed in the Humane Society of the United States's 2017 report on problem puppy-breeders.
Seven of the 12 are in Lancaster County.
The society has published the list for the past five years to inform the public about common, recurring problems at puppy mills.
Dogs living in feces-covered cages, maggots in water supplies, dead animals, newborn puppies screaming in pain, dogs with visible wounds, skin conditions and tumors, emaciated dogs, and dogs living in darkness and in crates too small for their size are some of the conditions mentioned in the report.
"For dogs in puppy mills, conditions like these are the norm — and no matter what the sellers say, breeders like these are the source of most dogs sold online, in pet stores or at flea markets," the society said in a statement.
Missouri had the greatest number of problem breeders, 19, for the fifth year in a row. Pennsylvania, Ohio, and Kansas followed with 12 each. New Jersey had one.
This year the society said its efforts were hampered after the U.S. Department of Agriculture in February removed all animal-welfare inspection reports and most enforcement records from the its website.
The society said it had some records from the USDA before the agency purged the online reports and that it also used state inspection records, court records, consumer complaints and media reports to compile the list.
Read the report here.