PINE RIVER — Animal protection officials have detailed filthy conditions at a northern Minnesota dog-breeding operation.

More than 130 dogs were seized and one carcass was recovered from the Pine River operation this week as part of an animal cruelty investigation.

Authorities removed 29 puppies and 104 grown dogs from the property Tuesday.

Humane Society investigator Wade Hanson says there were dogs “living in mud, water, green algae.”

Hanson says one dog was found dead in a doghouse, and he had “to dig it out of there.”

The Humane Society also released photos showing unsanitary conditions at the operation.

An attorney representing the couple who run the operation said the investigation is part of a politicized effort to bring about state regulation of the dog-breeding industry.