Alpacas were introduced to UK farms about 20 years ago
Three men were needed to free a farmer from the jaws of an alpaca after he stepped in to stop a "dominance fight" between two of the animals.
Rob Rawlins, 52, had to be airlifted to hospital after sustaining injuries at his Wellground Alpaca Stud Farm near Westbury, Wiltshire.
The farmer said the bite was not deliberate but he had "got in the way."
Alpacas, a South American relative of camels and llamas, are normally highly docile creatures.
Mr Rawlings said: "Two of the alpacas here were having a dominance fight and I tried to intervene, which was when I was caught on the arm by one of them.
"The bite had not been intended for me but unfortunately my arm got in the way."
Great Western Ambulance Service (GWAS) paramedic Mike Essery, who was first on scene, said: "On arrival I was told that it had taken three men to prise the jaws of the alpaca apart to release the man's arm.
"The bite was extremely deep and the man was in quite a lot of pain.
"Given the location I decided it was quickest to fly the man by air ambulance to hospital so if any micro-surgery was required he could receive it as soon as possible.
He added: "The man told me that alpacas are known to be very docile animals and don't normally bite, in fact he thinks this may be the first alpaca bite recorded in 14 years.
"The animal is due to have his fighting teeth - which are very large, sharp teeth at the back of the mouth - removed or filed for safety and it was these teeth that caused such a deep wound."
Alpacas were bred in South America for their coat, which was woven into clothing.
About 3,000 were introduced to Britain about 20 years ago, and their numbers have increased to 30,000, according to the British Alpaca Society.
Alan Brown, of the British Camelids Association, added: "I just find it staggering that it's happened. In 20 years I have been involved with camelids I have never been bitten."