Almost 30 sheep were attacked in Cadamstown, Co Kildare, on Friday night 27 January where 10 sheep were killed and another 19 ravaged.
Owner of the sheep James Mulligan said that there are another 87 sheep in the field that are traumatised following the attack and "may never thrive again".
Sheep kills in this area are an ongoing issue, he said, adding that this is the third or fourth sheep kill in the last few months.
"It's mentally and physically hard on any farmer to go through this. I couldn't face gathering up the dead ones until yesterday. I wouldn't wish it on anyone.
"It's not anything to do with money - it's an animal welfare issue and it's another job farmers just do not want to do. It’s not fair," he said.
Mulligan added that 20 sheep were killed in a field bordering the one where his were killed, but "nothing was done".
In a statement, gardaí said that investigations are ongoing.
Irish Farmers' Association (IFA) sheep chair Kevin Comiskey said he is getting regular calls from farmers over sheep attacks.
"This issue is ongoing and it has to be dealt with immediately.
"The Minister set up a working group on the issue and I told him I should be in it because I see what's happening on the ground," he said.
In a separate incident in Co Kerry, gardaí are investigating the theft of 31 sheep earlier this month.
The sheep were stolen from Castlegregory on the Dingle peninsula on Thursday 19 January.
In a statement, a Garda spokesperson said that no arrests have been made and investigations are ongoing.