A search is underway on Hamilton Mountain for a labradoodle named Cooper that escaped after it was mistakenly put on a WestJet plane to the Ontario city.

The dog's owner took a flight to Hamilton and has been searching desperately since Thursday as the city dealt with a massive rain and thunderstorm.

"My legs are aching and wet, and I'm starting to feel hopeless," said Terri Pittman, a Halifax resident.

Pittman put her dog on a flight from Halifax to Deer Lake, N.L., on Wednesday. Her parents were supposed to pick him up to take care of him while Pittman and her roommate planned to travel to Jamaica for a wedding in the next few days.

The dog ended up on a flight to Hamilton.

We'll stay out as late as we have to. - Lori Brodie , animal search and rescue volunteer

WestJet told her Cooper had arrived about midnight on Wednesday.

"I got a call saying they'd put my dog on the wrong flight to a totally different province," she said.

The dog escaped from its collar when airline staff let it out for a potty break.

At one point Thursday, Pittman told WestJet over the phone to put Cooper's crate, left open and with familiar-smelling things inside, by the road so that he might return to it. The crate was there for several hours, "but someone stole it a few hours ago," she told CBC Hamilton on Thursday evening.

'One of the worst days of my life'

Since Pittman has been in Hamilton, several people have aided in the search on Airport Road and nearby.

"I heard about it on the 6 'o clock news," said area resident Shannon Sacco. "So my mom and I decided to come and help."

Sacco said she saw about eight other cars on the road outside the airport, driving slowly with their blinkers on.

"The community of Mount Hope and Hamilton have been amazing," Pittman said. "Random people have messaged me saying they want to help."

As of late Thursday evening, there was still no sign of Cooper.

"It's been one of the worst days of my life," said an exhausted Pittman, standing inside the door of the airport in Mount Hope on Thursday evening as rain poured down outside.

She said she hadn't slept in at least two days.

Tips and sightings continued to roll in through social media.

"He's in Brantford," Pittman said at one point, as a new sighting was reported on Facebook.

Pittman is getting support from the women from Dream Team, a volunteer organization that searches and rescues lost animals. They advised Pittman to temper her expectations about the Brantford sighting.

The Dream Team, a group of local volunteers who help with search and rescue initiatives for lost pets. (Dave Beatty)

But they were resolute about continuing the search.

"We all have fur babies," said Lori Brodie, one of the volunteers. "That's why we do this."

"It happens far too often," Brodie said. She added they wouldn't be deterred by the bad weather or how far away Cooper could be.

"We'll stay out as late as we have to. It depends on how late the leads come in. We'll be out there."

WestJet covered the flights, hotel stays and meals for Pittman and her roommate to stay in Hamilton for the search.

"The safety and care of pets, whether they are travelling as cargo or as carry-on, is always a top priority for WestJet, and we sincerely apologize to the pet's owner for what has occurred," said airline spokesperson Lauren Stewart.

Stewart said the airline has engaged its staff in the ground search and put up posters.

"We will continue to work with the owner during this difficult time."

Anyone who may have seen the dog is urged to contact Hamilton airport security at 905-679-4908.