Alpaca farmer Jennifer McClay said her husband saw the dogs leaving their property after the attack at about 9.15pm.

Mrs McClay said it was the third time dogs had been spotted on their 13-acre property, and she worried that the dogs would return and attack the 12 unharmed alpacas remaining at the farm.

She described the attack on the animals, which the McClays farm for their fleece, as "absolutely horrific".

"There's a time bomb out there just waiting to go off," she said.

One alpaca was killed instantly by the dogs while three others were euthanised because of the severity of their injuries.

"It's not just the money, they're your animals," Mrs McClay said.

Another seriously injured alpaca was treated at the scene by a vet and a fifth escaped injury.

Mrs McClay said that she did not want to be overly dramatic about the incident but she thought it was important for Highlanders to be aware that the dogs were still unaccounted for.

They are described as being a red, tan colour and are believed to be Staffy cross-breeds.

A Wingecarribee Council ranger said if anyone saw a dog attacking another animal or leaving the scene of an attack, the best thing to do would be take a photo.

<#start#>

(function(d, s, id) {

var js, fjs = d.getElementsByTagName(s)[0];

if (d.getElementById(id)) return;

js = d.createElement(s); js.id = id;

js.src = "//connect.facebook.net/en_US/all.js#xfbml=1";

fjs.parentNode.insertBefore(js, fjs);

}(document, 'script', 'facebook-jssdk'));