Geronimo the alpaca could be put to death today as crowds of protestors prepare to march on Downing Street in a desperate bid to save him.
Animal lovers will descend on the capital in a last-ditch plea to spare the creature, who has twice tested positive for bovine tuberculosis.
They are set to demand the Prime Minister personally intervenes to spare Geronimo's life.
The animal's owner Helen Macdonald has threatened to film the last moments of her alpaca's life if the cull goes ahead and broadcast it on social media.
Last week, Ms Macdonald lost her final appeal to save her beloved pet at the High Court in London and now a warrant has been signed for his destruction. The Government reportedly has 28 days from last Thursday to carry out the killing.
She believes the tests are returning false positives, and has been refused permission to have him tested a third time.
Her plight has seen an outpouring of support, with more than 90,000 people signing a petition calling on Boris Johnson to halt the killing.
A protest will start at 2pm on Monday at Defra's headquarters at Smith Square in Westminster before heading to the gates of Downing Street.
The demo is being organised by members of the Born Free Foundation, the Alpaca Society, and practicing vet and bovine TB policy expert Dr Iain McGill.
Speaking before the protest, Dominic Dyer, from the Born Free Foundation, said: "Defra has known for many years that the TB skin test could be leading to false positive TB results in alpacas.
"However rather than allow Geronimo to be tested for TB using a more accurate Actiphage PCR blood test, Defra Secretary George Eustice continues to order his death to avoid greater scrutiny over the many failures in the Governments bovine TB control policy in cattle, alpacas and badgers."
The demonstrators will be joined by a number of alpacas who have been trained to walk with people and are comfortable around crowds, the organisers said.
The campaigners believe that Geronimo is free of TB and that Defra's tests are highly likely to be inaccurate.
They are demanding a different type of test be used to prove Geronimo's disease status before his death.
The protesters are calling for the Prime Minister to force the Environment Secretary to halt the killing and immediately implement the latest bovine TB tests for all suspected cases.
They also want to see an end to all further badger cull licences in favour of a vaccination programme for cattle, alpacas and badgers.
"The case of Geronimo the alpaca could well prove a major turning point in improving bovine TB control policy, in order to better protect cattle, alpacas and the future of our precious wildlife," Mr Dyer said.
The outcry over Geronimo's fate prompted George Eustice, who comes from a farming background, to write an article in the Mail on Sunday about his own experiences with bovine TB.
"Each week on average, we have to remove more than 500 cattle from herds due to infection in England alone. Behind every one of those cases is a farmer who has suffered loss and tragedy," he said.
"Farmers understand that infected animals are a risk to the remainder of their herd, so while the loss of individual animals is always a tragedy, the farming communities have worked with our Government vets in this arduous but necessary endeavour."
