Geronimo the alpaca was looking perky on Friday. His owner, Helen Macdonald, a veterinary nurse who has battled for four years to save his life, rather less so. “I’m still standing, that’s just about the best I can say,” she said. “It’s agony, to be honest. Mental torture.” After Macdonald lost the last stage of a sinuous court battle to stop Geronimo being put down this week, the Department for Environment, Food and Rural Affairs (Defra) gave her until 5pm on Friday to do the deed herself. She made it perfectly clear she was not going to do Defra’s “dirty work” and take the life of what she insists is a perfectly healthy animal, so the next, inevitable stage appears to be the arrival of men or women in a van who will euthanise the eight-year-old camelid. Geronimo has twice tested positive for bovine tuberculosis but Macdonald argues that the regime is flawed and has begged Defra to check again. The end appeared to be nigh for Geronimo when on Wednesday, far away from his field in south Gloucestershire, a high court judge in London rejected a last-minute attempt to save him. Macdonald has said she will not break the law to stop whoever comes for the animal doing what they have to do. But she has also said she will not help them, and that a live CCTV camera perched above his pen will broadcast to the world what goes on. She also has a band of supporters on hand ready to put up a “human shield” around the creature, if it is possible to do this without breaking the law. “I’m not saying how many we’ll have here,” she said. “I don’t want to give them an advantage.” Normal life has long been on hold for Macdonald. She breeds alpacas and usually runs training courses for people who would like to own one. She sends alpaca wool off to craftspeople in Devon who turn it into yarn, and the rougher bits go to someone in Nottingham who uses them to stuff duvets and pillows. That side of her business has had to take a back seat because of Geronimo. The stress is clearly taking a toll. “I’m a law-abiding citizen but they’re trying to break me,” she said. It is also affecting Macdonald’s 84-year-old mother. “She doesn’t sleep at night.” Macdonald said she planned to spend the day trying to prove Defra is wrong and exploring any fresh legal avenues with her lawyers, but she said she got the impression some people were just waiting for the “meat wagon” – and perhaps the riot police – to arrive. There has been an outpouring of support from the public, with more than 130,000 people signing a petition calling on Boris Johnson to halt the killing. Macdonald said she and Defra were at a stalemate but claimed there was still a way out, believing the government could order that Geronimo be kept alive and used for humane tests. “We’d learn something then. I’d just like George Eustice [the environment secretary] to come and sit down and talk this through.” The awful wait may not go on. Defra has committed to not using its warrant before 5pm on Friday, but it remains valid until 4 September. Defra said: “We are sympathetic to Ms Macdonald’s situation, just as we are with everyone with animals affected by this terrible disease. It is for this reason that the testing results and options for Geronimo have been very carefully considered by Defra, the Animal and Plant Health Agency and its veterinary experts, as well as passing several stages of thorough legal scrutiny. “Bovine tuberculosis is one of the greatest animal health threats we face today and causes devastation and distress for farming families and rural communities across the country while costing the taxpayer around £100m every year. Therefore, while nobody wants to cull animals, we need to do everything we can to tackle this disease, stop it spreading and to protect the livelihoods of those affected.”