DENVER -- A Denver woman is warning about a "Lost Dog Scam," after someone claimed to have her dog and threatened to kill it unless she paid hundreds of dollars. Animal protection officers say similar crimes preying on people with missing pets are on the rise in Denver and across the country.

"He's our baby. I have been desperately searching for him," said Kari McCabe, whose 5-year-old Shih Tzu disappeared Tuesday from her home near Sheridan and Yale after the kids who mow her lawn left the back gate open. "I would do anything at this point to get him back. I haven't eaten in two days. I haven't slept."

She posted his picture online, everywhere from Facebook to Craigslist, and 'Lost Dog' posters are all over the neighborhood, offering a reward.

But Kari never expected the response she got Thursday morning.

"I step out of the shower, and I see this text message, and it's, 'Hello how are you doing,'" said Kari.

The texter claimed to have her dog, texting "you have less than four hours to pay the sum of 500 dollars or your dog dies."

He even sent a photo that looked a little like Kari's dog. (A reverse image search showed it was a file photo online -- Not Buddha.)

"When you're so desperate to find your dog, you want to believe maybe it is your dog," she said.

Kari replied that she would pay even more if he could prove it was her dog. Instead she got a text saying "just consider him dead."

"I was honestly concerned about the animal's welfare," said Sgt. Joshua Rolfe with Denver Animal Protection, who said these types of scams are on the rise and the scammers are difficult to catch. "Usually once they catch wind of us calling or replying, the ad gets pulled or the phone number isn't working any longer. "

Rolfe said missing dog scams similar to this one are on the rise, but in some cases people actually find a dog (or steal it) and then demand hundreds of dollars to return it.

Similar scams are being investigated across the country, although in most cases the scammer never has the missing pet.

Some cons claim they found the missing dog in another state and need money for a plane ticket or a kennel. Others say they're truckers and ask pet owners to wire transportation costs.

In Arkansas, the Attorney General issued a warning about pet ransoms, saying some families have paid hundreds of dollars for pets they never got back.

"It's shocking there are people in this world like that. That would do something and prey on somebody who is heartbroken," said Kari.

Now, she just wants to warn others.

She still doesn't have Buddha back, but she's leaving the gate open, just in case.

"I just don't want it to happen to anybody else and of course I want my dog home," she said.

She is offering a $500 reward for his return.