A worried horse owner has issued a warning for people to be on their guard after she discovered one of her animals with a plait in its mane.

The owner, who lives near Shepton Mallet, but does not want to be named for fear of reprisals, fears her horse could have been targeted for theft by gypsies or travellers after similar incidents were featured in the equestrian press.

Horse owners claim the plaiting of a mane carried out by an intruder in daylight could be a signal for horse-stealers returning under covering of darkness. Feeling the plait in a mane could indicate the horse has already been checked as not being branded or micro-chipped and so is free from any identity coding that could prove it stolen when it later comes up for sale.

But other comments on websites say it could be a plague of My Little Pony fans just wanting to plait horses manes. And another correspondent states: "If they've got time to plait a mane they've got time to steal the horse."

Others claim it is nothing to do with potential thieves but more to do with pagan rituals and the full moon.

Shepton Mallet's police beat team manager PC Darren Walton urged horse owners to contact the police's Farmwatch team if they had concerns and to make sure their horses were micro-chipped.

"We have had two or three cases reported of horses' manes being plaited – but none were stolen. Some people seem to think it could be more to do with a Pagan ritual."

Equine vet Nicko Robertson from The Stable Equine Practice at the Bath and West Showground says that what appeared to be plaiting of manes could be the effect of the weather.

"Ponies' manes can appear to have been plaited but if they are out in the wind and rain they can develop what are like dreadlocks, with bits of leaves and twigs tangled up in them."

Mr Robertson said that modern technology was the best way of reassuring horse owners about the safety of their animals and preventing horse theft.

He said: "Since last summer all new equine passport applications have required every horse is microchipped as an unequivocal form of identification.

"To have your horse thus identified, and to advertise the fact with signs and rug patches, is probably your best safeguard against horse theft. There was a story last year of a pony abandoned on the dockside at Holyhead by thieves who realised it had a chip implanted and realised they could not sell it or ship it abroad.

"Once horses and ponies have been chipped, owners should put up signs telling would-be thieves this – it's the best way of stopping horse theft. Like any stolen property you are more likely to get it back if it can be identified."

Dr Liz Williams, author, director of Witchcraft Ltd in Glastonbury and an authority on witchcraft said: "I think it's likely to be a question of theft. It's certainly not part of standard Pagan or Wiccan ritual, which takes a dim view of messing about with animals (especially other people's animals).

"There is a folk tale that fairies plait horses' manes in order to ride them, because fairies don't use reins – but I don't think this is too probable in this case! In olden days, horse owners used to hang charms in the mane to stop this from happening."