Late last month, Kathleen Eaton of Amelia Island, Fla., went online to buy a dog. She found a miniature black schnauzer named Holly at a site she thought was puppyspot.com. She emailed the company and was told she could get the dog for a discounted price of $750.

She asked to pay with a credit card, but was told to wire the money to a Western Union in Oklahoma City. The company would then send her information about Holly’s flight the next day.

“My husband kept saying, ‘I don’t like this,’ but I didn’t listen,” said Ms. Eaton, 75, who retired four years ago from a career managing real estate offices.

She sent the money, and emailed again that evening asking for the flight number, but heard nothing. A few days later she reached out via email and was told that there had been delays, but that Holly would be coming soon. Then another email arrived requesting an additional $950 for health and insurance coverage. “I said: ‘You’re scamming me. I can tell your operation is phony,’” Ms. Eaton recalled.