The 48-year-old actor was thrown from the powerful animal while filming forthcoming Western movie `Lone Ranger` but he believes the strong bond he forged with the creature made it react instinctively to ensure his fall wasn`t as bad as it could have been.
Johnny - who plays the Lone Ranger`s Native American sidekick Tonto - said: "I`m lucky to be here. I`ve done a number of films on horseback and I`ve taken a couple of spills but this was a violent one.
"I had a good relationship with the horse, which was named Scout, and when I look at the tape I can see that Scout saved my life.
"I went down badly and I was dragged for 25 yards and in the end the horse just jumped over me and clipped me with his back legs."
Despite being a huge star, the `Dark Shadows` actor insists he isn`t a very ambitious person and doesn`t choose his roles by guessing how successful they might be.
When he embarked on his acting career, Johnny - who has children Lily-Rose, 12, and 10-year-old Jack with partner Vanessa Paradis - just wanted to be able to look back on his body of work and be proud of it.
He added in an interview with the Daily Mirror newspaper: "I never knew where I was gonig to go. I never really thought about where any of it was going.
"I only knew that, regardless of success or failure, I always wanted to some day be able to look back and go, `I did alright. I`m proud of what I did. I didn`t sell out.`
"I`ve never felt particularly ambitious or driven, although I like to create stuff, whether it`s a little doodle, a drawing, a small painting or a movie or a piece of music, so I suppose I`m driven by that. Everything I`ve done has felt natural."