Key Points:

The horse ridden by actor Viggo Mortensen in the three The Lord of the Rings movies has had lifesaving emergency surgery.

Brego, a 22-year-old Dutch warmblood stallion, was rushed to the Equine Clinic and Hospital at Massey University suffering from severe colic.

Senior lecturer in equine surgery Frederik Pauwels said Brego was in a critical state when he arrived. He was anaesthetised and surgeons found a large amount of small intestine stuck in a tear in his gut.

Colic is often caused by the bowel becoming twisted or blocked and signs include stomach pain.

Almost 2m of Brego's small intestine was removed before the ends were joined back together.

"Because of the severity of the case we expected there to be problems with him afterwards, but he did really great," said Mr Pauwels.

He said the horse would have suffered a "pretty nasty death" if he had not received treatment.

Brego, who is cared for by veterinarian Ray Lenaghan and his wife, Jane, at their 7ha property on the Kapiti Coast, stayed at the university's veterinary hospital for about a week before being released last Friday.

Mortensen and Brego formed such a close bond during filming of the trilogy that the actor eventually bought him. The Lenaghans have been caring for him since the trilogy was finished.

The horse has returned to the Lenaghans' property where he joins other Rings cast members including elven princess Arwen's silver stallion, Florian, Gandalf's cart pony, Clydee, and several Black Rider horses.

Mrs Lenaghan, who was the riding double for Liv Tyler who played Arwen in the trilogy, said Brego had been stabled and was recovering well.

"We'll just keep nursing him back to health. He's more or less retired but we still ride him occasionally."

Mrs Lenaghan said Mortensen was "obviously very worried" when he heard the news about Brego.

"But he was very thankful we acted quickly. It's a good thing his horse is as tough as old boots."

Mortensen said in an email to the Lenaghans he looked forward to seeing Brego again this year after completing a project in Hungary.

He is filming Good, based on the C.P. Taylor stage play. Mr Lenaghan was not sure when he would be back.