The 13 year old working dog was shot and killed on the evening of Friday, July 19. Police say a heifer also sustained what is believed to be a gunshot wound to its front left leg.

Gismo belonged to Greg and Lauren Newell of Linga Longa Farm.

The day after the shooting, they posted on social media: "It is a very sad day as we lost our beloved 13 year old kelpie Gismo.

"With him missing yesterday morning I drove the paddocks to find him dead near our favourite tree. At first I though it was old age but on further inspection I realised he had been shot. What scumbag shoots on private property, you may have thought you were shooting a fox but you have killed the most loving gentle pet and we are heartbroken.

"We have reported it to the police who will pass it onto the rural crime squad. RIP Gismo and may your paws always been crossed. We loved you and it just wont be the same around here without you."

A few days later, the Newells had received much support on social media. They posted: "We Greg and Lauren are overwhelmed by the out pouring of emotion, love and photos from you. From the bottom of our hearts we say thank you. Whilst every comment brings fresh tears knowing people care warms our hearts."

Rural Crime investigators are appealing for information in relation to firearm and animal cruelty offences committed on the property on Youngs Road, near the interesection of Cedar Party Road.

Spotlights had been seen shining into these paddocks and it is believed the dog was shot and killed in these circumstances.

Anyone with information is urged to contact Taree Police Station on 6552 0399 or Crime Stoppers on 1800 333 000.

"The Rural Crime Prevention Team and local police are committed to putting those responsible for this crime before the Courts. Please help us," a police spokesman said.