Eric Dane Has '1 Functioning Arm' as ALS Progresses

"Grey's Anatomy" star Eric Dane revealed he only has "one functioning arm" as he battles ALS.

The 52-year-old actor opened up about his condition during an appearance on "Good Morning America," which aired Monday.

"My left side is functioning; my right side has completely stopped working," he said. "I feel like maybe a couple more months, and I won't have my left hand either. It's sobering."

Dane underwent nine months of testing before finally being diagnosed with ALS, also known as Lou Gehrig's disease, a degenerative disease that causes progressive paralysis of the muscles.

"I started experiencing some weakness in my right hand," he said. "I didn't really think anything of it at the time. I thought maybe I'd been texting too much or my hand was fatigued, but a few weeks later I noticed it got a little worse."

Dane said he saw a hand specialist who referred him to another, then consulted a neurologist who also referred him to another neurologist, until finally he received the diagnosis.

"I will never forget those three letters," he said. "It's on me the second I wake up. It's not a dream."

Dane shared his concerns about losing movement in his legs and described a harrowing experience on a boat trip with his daughter. After jumping into the water with her, he suddenly realized he could no longer swim.

"I realized in the moment that I'm not safe in the water anymore," he said. "She dragged me back to the boat, and I was breaking down in tears."

The ordeal, Dane said, left him "heartbroken," adding that he's grown to resent his health challenges, especially knowing how they might affect his daughters' lives.

"I'm angry because my father was taken from me when I was young, and now there's a very good chance I'm going to be taken from my girls while they're very young," Dane said. His father died by suicide when he was a young boy. "At the end of the day, all I want to do is spend time with my family and work a little bit, if I can."

Known for his role as Mark Sloan in "Grey's Anatomy," Dane also stars in "Euphoria" and will appear in the Amazon Prime Video series "Countdown."

Speaking with Variety recently, the actor said he is "ready and willing to do just about anything" in the acting world.

"But I have limitations that I understand will preclude me from playing certain roles," he added. "I'm working on 'Euphoria.' I finished 'Countdown.' As far as that goes, I'm pretty capable."

• Ellen Pompeo Explains Why She Exited 'Grey's Anatomy'
• Ellen Pompeo: Detained by TSA After Bomb Squad Called Over a Snack