Prospective new pet owners are usually greeted by energetic young puppies with eagerly wagging tails and expectant lolling tongues in pet stores.Although almost every animal is presented as having been sourced from a caring and reputable breeder and to have enjoyed a happy life until that point, in the majority of cases that isn’t true.Puppies, as well as cats and rabbits for sale in US pet stores, including New York, most often start their lives in mass-breeding facilities in the Midwest and are brought up and transported in often deplorable conditions — which their owners rarely find out about.“Pet stores often advertise that their animals are ‘top quality’ and come from ‘responsible breeders,’ but the sad reality is that these dogs are trucked in from out-of-state commercial breeding facilities also known as puppy mills, where dogs often spend their entire lives in wire crates,” Bill Ketzer, senior director of state legislation for the Eastern division of the American Society for the Prevention of Cruelty to Animals (ASPCA), told The Post.According to the Humane Society of the United States (HSUS) there are 10,000 puppy mills in the US — licensed and unlicensed — which sell a combined total of about 2.6 million animals every year, according to their data.Former Petland employee turned whistleblower Miriam Arena, 26, started working at the large pet retailer’s Lexington, Kentucky store in October 2023. She told The Post she first learned the brutal realities of the industry when a “white transport van” arrived from interstate to deliver puppies to her store.“There were dozens of distressed puppies packed into cages on top of each other, soaking in feces and urine.They had no water and had traveled a long distance without being let out to move,” Arena explained to The Post.“The ventilation wasn’t even working and the transporters did not seem to care at all even though the puppies had been in there with the doors shut and no win...