"There have been a number of sightings of the dog over the past week and we were finally able to contain the animal in a property yesterday," he said.
The dog is being held by animal control while further inquiries are made.
Hastings District Council regulatory solutions manager John Payne said the scene was spotted by one of his team near Fernhill on Friday morning.
"One of our animal control team members was on their way to work when they saw sheep in the paddock looking bunched up, with some exhibiting blood."
They called it in and animal control attended immediately, finding about 80 sheep dead and another 25 injured.
A passer-by who contacted Hawke's Bay Today said he noticed the sheep dotted across the paddock when he was driving by.
"I saw the animal control vehicles there and when I saw the sheep I knew it was a dog attack," he said.
"There was blood everywhere and from the marks on the sheep and the mess left behind I could tell it was a dog attack because it's something I've, sadly, seen before."
Anyone with information about dog attacks on livestock is asked to contact police on 105 or anonymously via Crimestoppers on 0800 555 111. Alternatively, contact Hastings District Council Animal Control on 871 5000.
Stock owners should take extra precautions like:
• Electrify fences containing stock, especially if close to an urban area. A dog that gets a zap from an electric fence is unlikely to return
• Avoid home kills during the attack season
• House stock closer to home for monitoring at high-risk times, especially when newborn lambs/at the full moon
• Don't leave stock daggy during the attack season
• Don't leave dead stock unburied, skins out to dry, etc
• Take prevention measures against things like fly strike, foot rot, because these smells can attract dogs.