A NSW mum has had the difficult task of trying to explain to her two boys why someone would want to strangle their pets and urinate over their sheets and pillows this week.

Guinea pig, Salt, and rabbit, Twitch, were found dead and "twisted" in their Tolland home on Wednesday after thieves broke in some time before noon.

The intruders didn't take anything, but after killing the two pets someone decided to urinate over a number of bed pillows.

"I came home to my back window open and my kids' guinea pig and rabbit cage open," Kym Stevenson said, struggling not to cry.

"We panicked and my kids went to explore, I found the rabbit and someone had grabbed hold of it and ... physically done it.

"I'm appalled; it took all my strength not to be physically ill.

"My youngest son found the other guinea pig in his brother's bedroom door and he'd been killed the same way.

"There's no blood, no holes, you could see from the way they'd been killed it was done by a human.

"I don't know what I'd say to them, the people who could do that, it wouldn't matter what was said to them, it would be a waste of time.

"If you could do that to animals, imagine what you would do to a human being."

To add to the traumatic discovery, Ms Stevenson then saw that her pillows were covered in urine.

She described it as controlled and done in a way that you could tell was by a human.

This is the third time in 12 months Ms Stevenson's Bingham Place home has been broken into.

The first time thieves ate all her food and the second time they took her children's X-Box 360 and laptops.

Now she's moving because she doesn't want to live among the boarded up, vacant homes that surround her on the largely unoccupied street.

Ms Stevenson said the fact that someone had killed her children's pets had left her traumatised because she loves animals.

Most of Ms Stevenson's pets are foster animals from Best Friend's Pet Rescue.

After such a heart-breaking week she said she would focus her energy on having a pleasant Christmas with her boys Alex, 10, and Luke, 9.

"I feel really sad, it was scary and I loved them (Twitch and Salt) a lot," Alex said of what had happened.

Police are still investigating the incident, which they have described as disgusting.

Anyone with information is urged to contact Crime Stoppers on 1800 333 000.