Helen Macdonald repeated her calls for environment secretary George Eustice to quit, to chants from supporters of “murderer” at a demonstration outside his offices.
She has accused government officials of hiding from her how the animal was killed and how they “tortured” him on his final journey.
But the Department for Environment, Food and Rural Affairs (Defra) disputes Ms Macdonald’s reading of the results, insisting the post-mortem examination showed lesions, which will be tested in the coming months.
The alpaca tested negative for bovine TB before being imported in 2017 from New Zealand. He showed no symptoms since then, but Defra insisted subsequent tests on him had proved positive so he should be culled.
Officials, supported by police, finally led him to his death from his Gloucestershire farm last week, after a prolonged battle by Ms Macdonald and her veterinary adviser to prove the tests were flawed.
At the protest, campaigner Dominic Dyer branded Geronimo’s capture as “one of the most brutal incidents of animal crime in this country I have ever seen”, to cheers from supporters and chants of “shame on Defra”.
Ms Macdonald, a veterinary nurse, has requested the full post-mortem results, after her own expert was refused permission to attend.
She accused officials of “threatening and intimidating” her, and “wheeling out experts” who knew nothing about camelids.
“There is a long list of people who contributed to the barbaric treatment of Geronimo,” Ms Macdonald told the crowd. She claimed they were punishing her for daring to “stand up to their dogma”, refusing to tell her how her alpaca died.
“Geronimo was the innocent victim of arrogance, ignorance and greed,” she said.
At least nine camelids had died through multiple priming of an “unvalidated” test, she claimed.
Vet Iain McGill outlined how officials had stressed Geronimo in order to capture him, and had failed to take a proper head harness or to dart him.
The government says it would not have been safe to use a dart given numbers of protesters at the farm.
The animal was “primed” with tuberculin, which had boosted antibodies, which in turn had caused a false positive with the Enferplex blood test, Dr McGill said, insisting they had asked to talk to officials but had been rejected.
Chief veterinary officer Christine Middlemiss said: “A number of TB-like lesions were found, and in line with standard practice, these are now undergoing further investigation.
“These tests include the developing of bacteriological cultures from tissue samples, which usually takes several months. We would expect to complete the full post-mortem and culture process by the end of the year.”
Defra, which denied Ms Macdonald a third test while Geronimo was alive, said she was welcome to get a second opinion on the post-mortem report and government scientists were willing to any answer questions. Ms Middlemiss had made attempts to contact the owner, the department added.
Defra says microscopic lesions of TB can take a very long time to progress to larger, visible lesions, if at all.
Dr McGill, who used to work for Defra’s predecessor, the Ministry of Agriculture, said the preliminary post-mortem results showed no visible lesions, and no white or cream enlarged abscesses of the sort seen in TB in alpacas.
Government scientists could do a “Ziehl-Neelsen” stain test under a microscope, which would show any TB bacteria as large pink rods, he told The Independent, and they could also amplify the DNA to carry out a PCR test.
He issued a challenge to Defra chiefs to debate the science with him on live television.
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