Horne's friend and daily visitor, Alison Lawson, told supporters staging a 24-hour vigil outside the hospital that his condition had noticeably deteriorated during the day. "He is definitely worse," she said as she left his guarded room at York District Hospital. "Barry is still conscious but he is not able to focus any more.
Ms Lawson, Horne's nominated next-of-kin, added, "His spirits are amazingly high. His skin has changed colour now and his eyesight has virtually gone. The hearing in one ear has gone too and he can't hold down water any longer."
Once he loses consciousness Horne's living will comes into force, forbidding nurses from feeding him as he approaches his 63rd day without food. Bobby Sands, the IRA hunger striker, died in 1981 after 66 days.
Nevertheless, Horne is keen to hear press reports of his protest. "He remains very optimistic," said Ms Lawson. "He still hopes Labour will change their mind and announce a Royal Commission into animal experiments."
As Horne, a convicted fire bomber, lies struggling for breath his supporters wait at the camp they have built, flanked by placards and posters. Some are carefully laminated and carry considered arguments which highlight the Government's unfulfilled promises on animal rights. Other banners simply say "Don't let Barry die for Labour's lie".
It will not be long before he falls into a coma," confirmed Brendan McNally, one of Horne's former friends in the animal rights movement.
Another supporter, Sue Stone, has travelled to York on business and joined the vigil for part of the day. She is angered by suggestions that she and Horne's other supporters care about animals more than they do about people. "I don't think there is a choice. If you care about life you care about both," she said.
Her view was not shared by a middle-aged pedestrian who said she helps raise money for the hospital. "It's disgraceful that people like you are prepared to threaten other people's lives with your attacks," she said. "Let him commit suicide if he wants to. You should all go home and do something useful."