A barking dog has saved its family's life when their Cornish home was filled with a "potentially fatal dose" of carbon monoxide (CO).
Poppy the boxer dog raised the alarm at the Canworthy Water property in the early hours.
Liz Boult, her sons Charlie Prewett, seven, and Ollie Prewitt, four, and Ms Boult's partner Richard Harris were taken to Derriford Hospital.
A wood-burning stove is thought to have produced potentially lethal CO levels.
Inhaling the colourless, odourless gas reduces the blood's ability to carry oxygen.
Ms Boult and Ollie were treated and later discharged from hospital, but Charlie and Mr Harris are being treated in a hyperbaric chamber at the nearby Diving Diseases Research Centre (DDRC).
Cornwall Fire and Rescue Service said the amount of CO detected in the house could have killed the family within minutes.
Dr Christine Cridge, the DDRC's medical director said the family was "very lucky" to survive.
"Richard's a big hunk of a man, but when he found Charlie unconscious on the bathroom floor, he was so weak he could hardly lift him," she told BBC News.
"Thanks to prompt treatment, Richard and Charlie are doing really well - they've had two treatments of hyperbaric oxygen therapy and we'll do another one tomorrow."
It is not clear whether the family pet detected the gas, or was barking because she was unwell.
"They used to send canaries down mines, so although I'm not a vet, maybe Poppy was being affected by the gas herself because animals are smaller," Dr Cridge added.