A volunteer at a beloved no-kill Brooklyn animal shelter filed a lawsuit accusing the nonprofit of shipping unadoptable dogs to their deaths down south to make way for profitable puppies.

The explosive allegations against Sean Casey Animal Rescue were included in a small claims suit filed by Dana Paoli, who’s trying to claw back a $1,000 donation he made to SCAR after the death of Gunther, a pitbull mix who was euthanized in Arkansas over “aggressive” behavior.

But volunteers say the 3-year-old white canine was more Clifford than Cujo and was sentenced to death for taking up kennel space.

Gunther was euthanized last month due to “aggressive” behavioral problems. Facebook/Sean Casey Animal Rescue¿

“He was super-duper friendly. He wanted to meet everybody.…