Rob Lowe is mourning the loss of his family dog, Wayne

Alongside a picture of his pooch, Rob wrote: "We are heartbroken that our beloved Wayne passed away today. He was 14 years old. He was a curious, adventurous boy who loved playing chase, stealing snacks, and swimming. He was also a wonderful actor who did all his own stunts on our backyard Instagram show 'Abandon Crab'. We love you, Wayne!"

The 57-year-old star received several supportive comments from fellow celebrities as well as family and friends.

His brother, Chad Lowe, wrote: "Godspeed Wayne."

While his son Matthew posted: "He is in heaven swimming and stealing bread. Abandon crab forever," and his other son Johnny added: "Straight to Heaven."

There were also comments from Katherine Schwarzenegger and her brother Patrick Schwarzenegger.

Katherine wrote: "Poor Wayne!!! We love you Wayne ! (sic)"

And Patrick added: "Don't forget drinking jacuzzi water ! (sic)"

Meanwhile, Rob celebrated a whopping 31 years of sobriety in May this year.

He captioned a post on Instagram: "Today I have 31 years drug and alcohol free. I want to give thanks to everyone walking this path with me, and welcome anyone thinking about joining us; the free and the happy. And a big hug to my family for putting up with me!! Xoxo (sic)"

And the 'Outsiders' star also admitted he's still working on himself to this day, and whilst the process hasn't gotten "easier", he does feel more fulfilled.

He added: "All of my understanding about life has come from getting sober and being in recovery. The work that you do once you stop whatever it is you've been abusing - that's when the real work begins. And that continues to this day. In many ways, it doesn't get any easier but it does get more fulfilling.

"The only way to stay in recovery is to be honest with yourself on a minute-by-minute basis. No secrets, no double life. And you have to get real. That's what acting is all about - being real and being honest. The longer you are in recovery the more facile you are in getting honest. It really helps get you where you need to be [as an actor] a lot quicker."