Animal welfare groups, including the SPCA of Texas, are warning pet lovers of "dog flipping," which involves selling animals for quick cash, usually online. Sometimes the pets are lost, stolen, picked-up at animal shelters or purchased online for cheap and then resold.
Dog flipping is not a new trend but animal advocates say it's growing fast on Facebook garage sale sites.
"It's hard to track people down. Anybody can pose as somebody," according to Molly Peterson, president of Legacy Humane Society.
Peterson says the trend is pushing criminals to even steal pets. She says purebreds or rare mixes are often targets and what happens while they're waiting to be sold can be just as scary.
"I would like to think that in the meantime, the dog is in a plush bed and it's in an amazing home and maybe it came from a bad home, but the reality of it is it's not typically like that," said Peterson.
That's part of the fear for Wise County residents who've lost their dogs.
Nearly 40 dogs have been reported missing or stolen since November. The sheriff's office says it's checking social media sites as best it can. The sheriff says selling a lost or stolen animal is a crime.
Local
The latest news from around North Texas.
"It is, you know, it's a theft case," said David Walker, Wise County Sheriff, "If we saw someone selling dogs on the internet that belonged to someone else, that would be an issue."
Animal rescue groups warn buyers and sellers of pets online to tread with caution.
They say if you want to buy a pet online, ask the seller to see the animal's veterinarian records.
"If they have no vet records, or anything like that, it's a huge red flag that it's likely not their pet," said Peterson.
They also stress the importance of micro-chipping your pet. This will help authorities track you down in case your pet is lost or stolen and is flipped for cash.
"It's just a quick buck and it's a really sick, sick way to make a quick buck," said Cassie Evans, a board member for the SPCA of Texas.
Evans says the SPCA of Texas is caring for Gypsy, a one-year-old Chihuahua who was underweight with visible bald spots, a sign of starvation.
Evans says she first saw Gypsy in a "for sale ad" posted in a Facebook garage sale, online community groups in which users normally post household items for sale.
Evans says she suspected something was wrong, however, when she saw how much money the seller was requesting in exchange for Gypsy.
"There's no way that this woman bought a teacup Chihuahua for $800 to $1500 and then sold it for a hundred dollars to the first bidder," Evans said.
She then saw comments linking the seller to other dogs posted on Facebook under different usernames.
"She's three pounds. She's really, really innocent and delicate, and I just wanted to see her safe," said Evans.
Cassie purchased Gypsy for $100 so that she could turn her over to the SPCA of Texas, which will help Gypsy find a forever home once she's well enough to be adopted out.
"I just want Gypsy to be loved and taken care of like she should be and not sold like an iPhone, or a toaster or a vacuum on Facebook," Evans said.
NBC 5 spoke to the woman who sold Gypsy to Evans. She declined to speak on camera but says she has never sold another dog online and has never changed her name on Facebook, as commenters on her post had accused.
She also says she bought the Chihuahua from another Facebook seller in the condition it was in, however, couldn't keep the dog because she had moved in with daughter.
Animal welfare groups advise that if you're no longer able to care for a pet, or if you're in search of a new pet for you family, your safest bet is to go to an animal shelter or rescue group.
