The owner of a therapy alpaca, which was fatally injured in a dog attack on Tuesday, is distraught over the loss and the fact the incident was allegedly filmed by the dog's owner.

Key points: Mimosa the therapy alpaca had both front legs broken in the attack and had to be euthanased

Mimosa the therapy alpaca had both front legs broken in the attack and had to be euthanased The dog's owner allegedly filmed the incident

The dog's owner allegedly filmed the incident ACT Domestic Animal Services is investigating the incident and is seeking information that could help identify the dog's owner

Nils Lantzke told ABC Radio Canberra he was walking his two alpacas, that support Canberrans in mental health units and hospices, in Giralang when he said they were approached by a young man and his black staffy dog.

Mr Lantzke said he was holding the lead of one of the alpacas, called Hercules, while his friend was holding the leash of the second one, named Mimosa.

When they saw the man and his dog approach the pair on the bike path, Mr Lantske said he asked the owner to keep his dog away.

"But he persisted and started filming and the dog attacked and I was yelling at the time, screaming, 'get your dog off the alpacas!'… but he didn't do anything," Mr Lantzke said.

"He attacked Hercules first, the white boy, and Hercules went into classic attack position on his hind legs, to attack the dog, but the dog left him and attacked Mimosa, a tiny little girl.

"And the dog just went to town on her."

In an effort to save Mimosa, Mr Lantzke said he "belted" the dog with a heavy stick, which angered the owner.

Mr Lantzke said his friend, being "small and not well," was forced to let go of the lead to prevent herself being injured, which caused the dog to chase Mimosa up the street.

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Alpaca 'nearly made it home'

"Mimosa tried to get home, she nearly made it, but when we found her she was lying on the grass, with a deep wound in her leg," he said.

"We just stayed with her, she was in terrible pain. Both front legs had been broken and her left leg had been bitten to the bone."

Hercules did not appear to be injured and the dog was nowhere in sight, with Mr Lantzke saying the last he saw of the animal was it being held by its owner.

Mimosa had to be taken to a vet to be euthanased.

"The other alpaca slept near the gate hoping that Mimosa would come home," an emotional Mr Lantzke said.

He said he was now hoping authorities could find the dog's owner, who he said filmed most of the attack on his phone.

"I just hope he somehow has a wake up call and doesn't do this to somebody else," Mr Lantzke said through tears.

Nils Lantzke with a llama-alpaca cross named Forest Gump. ( ABC Canberra: Hannah Walmsley )

But he vowed to continue his work despite the horrific incident.

"We are just here to help people. My alpacas and llamas, we have always done it just to create smiles, and we'll keep on doing that."

"Nothing is going to stop us."

Mr Lantzke said he tried to report the incident to police but was told the ACT Government's Domestic Animal Services handled these investigations, which the DAS confirmed.

A DAS spokesman said the matter was "under investigation".

Dog attacks on alpacas are common, breeder says

Rob Harborne breeds alpacas in Murrumbateman, a New South Wales town just north of Canberra, and said he had lost "about eight" alpacas to violent dog attacks, with several more seriously injured.

"They're always domestic dogs," he said.

"People go away and leave their dogs unattended, or in a non-secure section, and they get into a pack and … they think it's a bit of a game."

Mr Harborne said some dog breeds were known to attack alpacas more often than others, but that no specific breed was the issue.

He said the problem was owners not keeping their dogs sufficiently constrained.

"I've had alpacas with their back legs broken because, as they're running away, dogs follow them and smash their back legs," Mr Harborne said.

"I've been in contact with a lot of other breeders who've had the same thing happen and a lot don't have insurance... the owners have to foot the bill for the recovery if they're not dead and cop the loss if they are, which can sometimes be a lot of money."

The ACT's City Services Minister Chris Steel said his thoughts were with the therapy alpaca's owner and that DAS was taking the matter very seriously.

When asked why police could not do anything about the attack, he said the ACT Government recently came to an agreement with police that these types of matters would fall under the responsibility of DAS.

"If anyone has any information on the attack or the dog or the owner, call Domestic Animal Services on 13 22 81 and call 000 if the attack is happening at the time," Mr Steele said.

"I have confidence DAS will get to the bottom of what has happened and who the owner is."