Among the allegations is that Durkin vaccinated puppies without the supervision of a licensed vet, failed to have them properly examined as required by law, and failed to advise consumers they could return a puppy, or recoup some medical costs, if it became ill within 14 days of purchase.
Mackay, whose collie, Hannah, survived but has problems, and animal activists say they hope the case raises awareness about the obligations of dog breeders and brokers to provide veterinary care and documentation.
Steve Lee, acting director of the Division of Consumer Affairs for the Attorney General's Office, said his office wants to make sure dog brokers and breeders comply with New Jersey law.
"We are concerned about the allegations that this business sold sick puppies without disclosing important information to consumers or following other requirements of the law," Lee said. "We will investigate any and all consumer complaints about businesses that sell puppies or other pets."
Durkin is accused in a civil complaint of violating consumer laws. She does not face criminal charges and can continue to sell dogs.
She declined to comment and referred questions to her attorney, Pennsville lawyer Paul Scull, who could not be reached. In a story earlier this month, Scull said he could not comment on pending litigation.
Fresh pictures of puppies appear weekly on Durkin's Prada Puppies' Facebook page, which has more than 7,000 likes.
In December 2012, after seeing a newspaper ad, Mackay paid $400 cash for Hannah. Shortly after Hannah arrived at Mackay's home, the puppy seemed fearful, did not like to socialize, and growled, Mackay said. The odd behaviors led her to question the quality of Hannah's breeding, she said. A veterinarian suggested Hannah see a dog psychiatrist.
Mackay wishes she had done more research. "I would tell others to go to a reputable breeder or animal rescue group," she said.
Judy Morgan, a veterinarian of more than 20 years with offices in Gloucester and Salem Counties, said she had treated puppies sold by Durkin's business for a variety of illnesses, including genetic disorders and parasites. Dogs that are inbred, she said, often have poor immune systems and require much medical care throughout life.
Morgan accused Prada of "cranking out dogs for money."
Reputable breeders, Morgan said, keep extensive documentation on dogs and their bloodlines to minimize genetic disorders. "Puppy mills" disregard safe practices, she said, and often sell genetically defective dogs to brokers at low prices. The brokers then sell the puppies for hundreds of dollars.
"They sell them out of the back of their cars and out of their vans," Morgan said. "It's a tragedy."
New Jersey has long been a dumping ground for puppy mill owners, including those in Pennsylvania and Ohio, she said.
Libby Williams of Hunterdon County started a nonprofit in 2003 to help identify problem breeders and educate consumers. Her organization, called Pet Watch New Jersey, has taken numerous complaints about Durkin, she said. When appropriate, Williams said, she refers people to the Attorney General's Office.
About two years ago, Christian Guevara said, he drove from North Jersey to meet Durkin in Salem County. He paid $500 for his Boston terrier, Joey. Shortly afterward, Joey needed more than $2,000 in vet care and was diagnosed with the knee disorder luxating patella. Guevara said he never considered returning Joey because he had bonded with the dog in a way he considers "a lifetime commitment."
Mackay said she feels the same about her "beautiful girl" with quirky behaviors. She recalled a recent walk in which Hannah was excited, with her tail swishing, when she noticed a statue of the Virgin Mary holding Jesus. When the mysterious woman did not respond to Hannah, the dog's ears went back and she barked aggressively at the statue as Mackay pulled her away.
"I love her to pieces, but she's a basket case sometimes," Mackay said.