In one of the starkest reminders to date of the dangers of texting while driving, the late [article id="1645913"]celebrity plastic surgeon Dr. Frank Ryan[/article] was reportedly tweeting about his dog just before his car plunged off a cliff in Malibu on Monday.

Ryan, best known for performing several surgeries on "The Hills" star Heidi Montag, was killed when his 1995 Jeep Wrangler fell off the side of the twisty Pacific Coast Highway and fell on its roof.

Ex-girlfriend Charmaine Blake told People magazine that Ryan was sending out a Twitter message about his border collie, Jill, just before his crash. "He lived up in Malibu on a tiny street, and he was texting while driving, and he accidentally went over the cliff," she told the magazine. Blake added that Ryan's family was told by crash investigators that the texting caused the wreck.

A California Highway Patrol spokesperson confirmed for People that Ryan was texting before the crash, but investigators have not yet determined the official cause of the accident. The dog was ejected from the car, but survived, sustaining head, eye and paw injuries.

On Ryan's Twitter, the last post reads, "After 25 years of driving by, I finally hiked to the top of the giant sand dune on the [Pacific Coast Highway] west of Malibu. Much harder than it looks! Whew!" That missive was followed by a photo of Jill looking out at the Pacific Ocean with the caption, "Border collie jill surveying the view from atop the sand dune."

Celebrity publicist Blake, 29, who lived with Ryan from 2003 to 2006, said she remained close to the surgeon and hoped that his death will remind people that they "should not text and drive at all."

TMZ reported that the 50-year-old doctor was trapped inside his vehicle and suffered from major head injuries. He was pronounced dead after Ventura County Fire Department officials tried to lift him out of the wreckage with a helicopter.

In addition to famously working on "Hills" star Montag, Ryan's other patients included Vince Neil, Gene Simmons, reality-TV personality Adrianne Curry and Lorenzo Lamas. Montag took to her Twitter page to express her condolences.

"I am devastated to hear the news of Dr. Frank Ryan's death," Montag wrote on Tuesday. "He was the most amazing person I have ever known. He was an angel and changed my life and the lives of everyone he met. He was the most brilliant talented surgeon who will ever exist. Dr. Frank Ryan changed the world."