Horses and ponies found living in squalid conditions at farm in Antrim
More than 60 animals have been rescued and nine found dead at a farm in Antrim.
The horses and ponies were discovered a week ago in squalid conditions by a vet at the premises on the Lisnevenagh Road.
Police found the animals living amongst the carcasses of nine dead animals.
Four animals were found to be in such poor condition that they had to be humanely put down.
Investigating officer Sgt Alison Liddle said police were met with a "truly heartbreaking scene".
"These animals were effectively starving to death in the most dire of conditions - there was no clean bedding, no water and nowhere for them to move around," she said.
"Live animals were being forced to live next to the rotting carcasses of other dead animals. No animal should be made to endure such horrendous cruelty. Every officer who attended has been affected by what they saw.
"This has made us determined to pursue the persons responsible and make sure they are found amenable for their despicable cruelty in a court of law."
The police were assisted by staff from the Crosskennan Lane Animal Sanctuary.
Janice Watt from the sanctuary said even though they had removed a lot of animals from the site, they had had to put some to sleep.
"Unfortunately we are expecting further fatalities due to the degree of starvation and neglect they have suffered.
"Another had to be put to sleep on Monday, she was simply too weak to stand, we could not get her to her feet."
Ms Watt said there was an "equine crisis" currently happening in Northern Ireland which was also affecting the Republic of Ireland as well.
"What is happening is that the bottom has fallen out of the horse market, essentially the value of horses has dropped significantly," she said.
"What we're finding is that a lot of dealers are buying up all these horses because they are so cheap, some are going through sales for as little as £2.50, so they are buying so much stock and not thinking about the level of care and the amount of money it is going to cost to look after that stock."
She said it was important that people were aware of the costs of keeping a horse or pony.
"We always advise people when they're thinking of taking a horse on that it is going to cost between £2,000 and £3,000 a year to look after that animal," she said.
The charity is the only one in Northern Ireland which takes in horses.
"We're receiving a massive number of calls every day about horses in need," she said.
"We're completely volunteer run so it is very difficult for us to meet the demand of all of those calls.
"There is no statutory or government agency that is actually taking on responsibility for this so it means that the problem is much much greater than the resources we have as a charity to cope with."
Ms Watt said a lot of cases of animal neglect happened on private land so were hard to detect.
"It is normally a neighbour or someone who notices something, maybe a dead horse lying in a field that alerts us to the problem and that normally is just the tip of the iceberg once you get in there," she added.