The letter warned the Warwick resident that if she didn't "shut that dog up" the person would "cut the f***** things throught (sic) and yours".

Adding insult to injury, the vile note was targeted at a Southern Downs Ark foster carer, who was simply trying to do good by taking in abandoned animals.

"I had to read it twice to make sure I was reading the correct thing," the foster carer said.

"In my head I was thinking, 'Why wouldn't they just come to the front door and talk to me about it?"

The woman said this was the first complaint she had received for dogs Bear, Spot and Jasmine.

"They're all pretty quiet," she said.

"Most of the neighbours didn't even know we had the dog."

The three dogs were all surrendered to Southern Downs Ark, and are waiting to be rehomed.

"We take them in, work them, try to give them some manners so they're good enough to rehome," the foster carer said.

"When they're good enough to rehome they go on a national website to find a forever home"

The owner said she doesn't know who put the letter in their letter box, or why they felt the need to use such aggression.

"Can you hear them at the moment?" she asked.

"The letter was in mailbox yesterday.

"We had another girl who was adopted.

"She was a bit yappy, but at night-time she slept inside the house.

"But it's because there are so many dogs around the neighbourhood that yap."

Warwick police officer-in-charge Senior Sergeant Jamie Deacon said threats sent by letter were a serious crime.

"If there is a conflict between parties or the reception between them is not good, progressing that to threats is lunacy," he said.

"If people have a beef, there is a forum where they can make complaints through council."

If you are not comfortable approaching the owner when the dog barks excessively, or if the dog continues to bark after the owner has had time to resolve the problem, you can report the issue to by calling the council and providing them with basic details.