Hamilton writes on Instagram that his 12-year-old bulldog Roscoe was revived after a cardiac arrest when he was being treated for pneumonia.
"We do not know if he will wake up. Tomorrow we will try to wake him up, I am by his side and want to thank everyone for your prayers and your support", he writes.
Roscoe has become well-known in the Formula 1 circuit where he often accompanies his owner. Roscoe also has his own account on Instagram with 1.3 million followers.
