Sgt Rob Taylor has called for the law to be updated to also cover animals, such as alpacas and lamas, and increase sentencing powers.
He said more than 2,000 sheep have been killed in nearly 500 dog attacks since 2013.
The North Wales team and four other UK forces will present their findings to Parliament at the end of the year.
The NFU and FUW farming unions have said they too support the campaign for a new Protection of Livestock Act.
Sgt Taylor said the current powers of sentencing "do not reflect the true accuracy of the loss to the farmer and the offence involved", and called for powers in relation to the seizure of dogs and banning orders on owners.
Iestyn Pritchard, of NFU Cymru, said figures showed there were about 100 cases in 2013 but they were now "closer to about 1,000" per year, meaning the problem was getting worse.
"There is obviously the financial effect of losing stock, we always think in terms of the lambing period, but there's also the stress involved with having to deal with dead sheep or severely injured sheep.
"When you're trying to run your own business, you're on your own land and you're finding outside influences are having a direct impact on your business and you can't control it," he said.
He added rather than just taking one dog for a walk it was a growing trend to take out two or three, making it more difficult for the farmer and dog walker to control a "pack of dogs".
Police need more powers to stop dog attacks on sheep, the head of rural crime in north Wales has said.