Lewis Hamilton's Dog, Roscoe, In Coma, Fighting For Life in Hospital

Lewis Hamilton is asking his fans to send some serious well wishes after his dog, Roscoe, was placed in a coma this week ... revealing his beloved friend's condition remains uncertain amid a pneumonia battle.

The Formula One legend shared the heartbreaking story on his Instagram, posting photos of himself right by his English Bulldog's side in the hospital and detailing what they have gone through this week.

"Please keep Roscoe in your thoughts. I want to keep you all updated. Roscoe caught pneumonia again and was struggling to breathe," the Ferrari driver said on Friday.

"He was admitted into the hospital and sedated to calm him while they did checks on him and during the process his heart stopped."

Hamilton, 40, said doctors managed to secure a beat for Roscoe's heart ... but he is now in a coma.

"We don’t know whether he will wake from this. Tomorrow we'll try to wake him up. I'm by his side and want to thank you all for your prayers and support," Hamilton said.

Hamilton is a seven-time champion, but Roscoe is a star in his own right with over one million social media followers ... and he even made a special appearance in "F1: The Movie." He's also a brand ambassador for plant-based dog food companies ... as he's vegan, just like his dad.