There's a crazy thing happening along the southern border -- migrants attempting to enter the United States with their dogs are forced to leave them behind, and it's creating a whole other crisis.

FNC reporter Matt Finn is on the ground in Eagle Pass, Texas and joined us Thursday on "TMZ Live" to reveal what he's seeing firsthand ... and how he and other TV crews are getting involved, and taking some of the dogs in themselves.

Matt says tons of migrants are trying to cross the border with their dogs, only to be told they can't bring the pups with them to federal processing centers ... resulting in strays roaming the border.

The circumstances leave dogs in need of food, water and shelter ... and Matt says troops with the National Guard are taking care of some of the doggos ... and he and his producer have helped out too.