DNA tests have been carried out by police as the search continues for the animals that mauled a flock of pregnant ewes at a farm near Haywards Heath.
The shocking attack back in January saw 32 sheep seriously injured at Hillsdown Farm in Horsted Keynes, 15 of them so badly they had to be put down.
Police confirmed at the time that it was the second such incident in the area in a matter of weeks.
And the culprits are still at large, according to a spokesman at the farm, who said the investigation was still ongoing.
“We are still waiting on the DNA results taken from a number of dogs in the area,” said a spokesman. “We remain hopeful that we will at least be able to identify the litter the dog came from.”
A new campaign urging dog owners to keep their pets under control has been launched by rural insurer NFU Mutual, after new figures reveal the cost of dog attacks on livestock.
A spokesman for NFU Mutual said: “As the insurer of three-quarters of the UK’s farmers, we are sadly all too aware of the heartbreak and distress that dog attacks on livestock cause.
“That’s why we are urging dog owners to keep their pets on a lead at all times in the countryside and for people to report out-of-control dogs to a local farmer or the police.
“Known as livestock worrying, dog attacks on farm animals can result in horrific and often fatal injuries.
“Even if a dog doesn’t make contact, the distress of a chase can cause sheep to miscarry their lambs and sometimes die from exhaustion.
“We believe that a significant proportion of attacks are now caused by owners who let their dogs roam from homes adjoining the countryside and either aren’t aware that they are attacking farm animals - or don’t care.
“To help farmers tackle livestock worrying, we have commissioned research into dog owners’ attitudes to exercising dogs in the countryside and have launched a campaign to highlight the importance of keeping dogs under control.”
Although more dog owners are putting their pets on leads when livestock are nearby, more owners are allowing their pets to go out in the garden unaccompanied when they’re out, a spokesman said, despite one in six owners admitting their dog has escaped from home.