Police responded and a helicopter with thermal-imaging cameras flew over the field.
Wildlife experts at a local zoo were consulted and made preparations to send a team equipped with tranquilizer darts.
"We offered advice to the police and we immediately gathered a team of staff who have been trained to deal with situations such as this," John Pullen, curator of mammals at Marwell Zoo, said.
"We were moments away from making the journey when we received a call from police to say it was a stuffed toy."
The toy was being considered as lost property, Hampshire police said, but they were investigating whether it was a hoax.
They don't how it ended up in the field, they said, but noted it was similar to one that might be won as a prize at a fair or carnival.
