Stony Creek, Connecticut — Former Navy SEAL James Hatch was a dog handler on scores of raids in Iraq and Afghanistan until he was badly wounded in 2009. His leg still gets stiff in cold weather, but with the help of his service dog Mina, he's back in action as a 52-year-old freshman at Yale University.

Hatch suffers from post-traumatic stress disorder, but Mina's got his back.

"Mina will just sit behind me and it just makes me feel like, OK, if somebody wants to do anything, they'll have to go through Mina," Hatch said.

Mina doesn't like gun fire so she is strictly a service dog. But she comes from a family of war dogs.

Mina is James Hatch's service dog. CBS News

"They can do the work of four or five guys. They can find explosives. They can alert you to the, to people hiding in walls or behind curtains," Hatch said.

He said these dogs don't "understand bullets," but they save lives. Hatch went on about 40 missions with his first dog Spike.

"I sent him to bite a guy and I started putting rounds into the guy. One of the bullets went through the human and into Spike and killed him," Hatch said.

Hatch lost four dogs in combat. He's started a fund to help care for war dogs when they come home.

"I think it's important that we understand what we're asking these dogs to do on behalf of humans," he said.

Mina is 60 pounds of fast-twitch muscle and off the chart energy. She is an awesome animal — too awesome for most humans to handle.

"People are keen to have a dog like this in their life and they don't really understand the amount of work," Hatch said. "We get regular emails from people and they say I can't handle this dog."