The government says it is “not possible” to explain how an alpaca from South Gloucestershire may have caught bovine tuberculosis.
Geronimo the alpaca, who lived on a farm in Wickwar, was put down in August after previously testing positive for the disease.
The Department for Environment, Food and Rural Affairs (Defra) published the post-mortem test results today (December 10).
They maintain the animal had “TB-like lesions” but said “it was not possible to culture bacteria from tissue samples taken”.
“This does not mean the animal was free of bTB infection because it had previously twice tested positive using highly specific, validated and reliable tests,” the report stated.
Geronimo, from New Zealand, was a pedigree alpaca worth £15,000.
The eight-year-old twice tested positive for tuberculosis in 2017 but its owner Helen Macdonald disputed the results.
She claimed Geronimo had given false positives.
Chief veterinary officer Christine Middlemiss said the post-mortem tests results were complicated by the “complexity of the disease”.
“This animal tested positive for bovine tuberculosis on two separate occasions using highly specific tests,” she said.
“Due to the complexity of the disease, further testing has not enabled us to use Whole Genome Sequencing to try to understand how the animal became infected in the first place.
“Our sympathies remain with all those with animals affected by this terrible disease which devastates farmers’ livelihoods.”