DENVER (KDVR) — TSA has a warning for anyone hoping to take their pets along for their holiday travels after agents at two airports recently got a shock at the X-ray machine.

At airport security checkpoints, TSA agents are trained to see through the fancy carry-ons and spot all sorts of threats.

“The most common types of items we see are knives and tools and martial arts items,” TSA Colorado spokesperson Lorie Dankers said.

However, pictures and X-rays capture what agents spotted at airports around the country in the past few weeks as TSA discovered two pets during the X-ray screening process.

The first happened just before Thanksgiving at LaGuardia Airport, where a cat was in a checked bag. The second incident happened about a week ago in Wisconsin, where a dog was concealed in a backpack and was screened through the X-ray at the security checkpoint.

“You can only imagine the shock of the TSA officer operating the X-ray,” Danders said. “What was interesting is the traveler was actually planning. They had declared their pet to the airline, but they had kept it in a backpack to send it through the checkpoint. There’s really no need to do that.”

Flying with pets? What TSA wants you to know

TSA will screen pets via the security checkpoint. Agents suggest pet owners expect the following:

All pets should be bought to the security checkpoint in a handheld travel carrier.

Remove the pet from the carrier just prior to the beginning of the screening process.

Place the empty travel carrier so it can go through the X-ray process.

Never place a pet in the X-ray tunnel. If possible, carry the pet during the screening process. Alternatively, the pet can walk through the screening process if the owner has the pet on a leash.

TSA says pets should travel in the cabin of the aircraft with their pet owners.