Story highlights EXCLUSIVE : John Ensign is now working at a veterinarian hospital he once owned

: John Ensign is now working at a veterinarian hospital he once owned Former Nevada senator left Washington amid a sex scandal

Once the only vet in Congress, he is now taking classes to brush up on his skills

He is introspective, warning those still in politics not to let power get the best of them

One minute, he's checking a cat's mouth for gingivitis. The next, he's carefully bandaging a dog's bloody, broken nail.

This could be any hard-working veterinarian tending to ailing animals. But the embroidered name on his crisp white medical coat bears a familiar name: Dr. John Ensign.

He's better known as former Nevada Sen. John Ensign, who abruptly announced his resignation 10 months ago amid a high-profile sex scandal.

"I built this," Ensign told CNN in an exclusive interview inside West Flamingo Animal Hospital, where he now works.

"It was the first 24-hour animal hospital in Las Vegas, and Dr. Yak [the current owner] bought this from me, and now I'm working for him," he mused, calling it humbling, yet also "a very healthy thing to have happen in life."

Ensign was the only veterinarian in Congress. He hadn't practiced since becoming a U.S. senator more than a decade ago.

Ensign took CNN on an exclusive tour of the animal hospital, just a few blocks west of the Bellagio hotel and famous Las Vegas Strip. Stopping to look at a large dog getting a digital X-ray, he points to the image.

"You can tell he's had a crushed pelvis there," he said.

"You see our X-ray equipment? It's all digital now."

He said he works hard to get up to speed on the changes in technology and techniques since he was elected to the Senate.

"Literally, I'm studying, you know, till 10, 11 o'clock every night and just trying to make sure that I get back up to a very high level in veterinary medicine," Ensign said.

"There's been a steep learning curve, and I've gone to continuing-ed [education] conferences. I've spent time with specialty practices, both in California and here," he said.

He insists veterinary medicine is where his heart is.

"I loved being in the Senate. That was a wonderful experience. But I'm putting as much passion into this as I did that, and so I'm really enjoying it. And the other nice thing is being home every night, you know, seeing my wife and kids every day," Ensign said.

Ensign is still with his wife, Darlene, and says they're doing "great" -- healing after his extramarital affair with Cynthia Hampton, a longtime friend and employee, led to his political downfall.

Last spring, the Senate Ethics Committee issued a lengthy, stinging report with a torrid narrative of the affair, accusing Ensign of violating the law by trying to help Hampton's aggrieved husband -- a former staffer -- find lobbying jobs.

Ensign, an evangelical Christian, resigned three weeks before the report came out. When asked if he left Congress to avoid testifying before the Senate Ethics Committee, he said, "My family had been through enough. I didn't want to put them through more."

Ensign and his wife have three children, two boys and a girl -- one in college, one in high school and one in junior high.

The committee report recommended that the Justice Department investigate Ensign for violating the law, but he told us he has no indication that is happening.

"I haven't heard anything since I left. I really don't think about it until somebody like you asks me about it," he said.

But he did offer that he didn't think the ethics report was fair, saying it published the report without incorporating what Ensign submitted.

"They did not even consider our side in it," Ensign said.

He is introspective about his fall from grace, warning those still in politics not to let power get the best of them, as it did him.

"Do everything that you possibly can to keep yourself grounded. And a big part of that is keep people surrounded, keep people around who basically will slap you upside the head and tell you when you're doing wrong," he advised.

Didn't he have that?

"I thought I did, but after a while, you develop invisible barriers and to where they're actually intimidated to do that, even though I would say it all the time," he said.

"Even when you really value people, you can still develop a little bit of an arrogance that you don't even see in yourself."

Ensign's political star was once so bright, the former member of the Republican leadership in the Senate had pondered a presidential run. Does he have pangs now, watching GOP contenders like Mitt Romney and his old friend Rick Santorum go at it?

Ensign shakes his head.

"The chances for me would have been so slim anyway, but you know you can't go back, you can't look back. I'm looking forward to veterinarian medicine, I'm having a ball."

When he's not at West Flamingo Animal Hospital, Ensign spends his time at an animal shelter neutering dogs and cats -- and the shelter sometimes does hundreds in one day.

He recently had to put a dog to sleep for the first time since returning to veterinarian medicine.

"It was an older dog, and you know I held the lady, I hugged her. She wanted to be there when the animal was put to sleep. It was her husband's dog, and he died four years ago, and so at the same time, you look at that as an incredible responsibility to be there for people," Ensign said.

It's those moments that make Ensign call veterinarian medicine his life's passion.

And what about the politics? The profession he was forced to leave?

Ensign tries to keep a sense of humor about it all.

"You know the bark is worse than the bite in D.C.," he said, tongue firmly in his cheek, adding, "I was vaccinated for rabies."