The RSPCA says it has found no evidence of neglect after a dead horse was found on land near The Embankment in Wellingborough.
Many people voiced their worries on social media after the horse was discovered under a tree opposite the water park.
The RSPCA has come under fire from residents over an alleged lack of response to the concerns, which have been in place for several years.
But the charity has confirmed that while it is aware of concerns, it appears that the horse died of natural causes.
A spokesman for the RSPCA said: “The RSPCA is aware of concerns about a group of horses being kept on land near The Embankment in Wellingborough and has visited to check on their welfare.
“The horses are currently being provided with a nutritionally-adequate diet and are sustaining normal bodily conditions.
“They also have a constant source of water.
“There are no urgent concerns for their welfare.
“We are very sorry that one of the horses has died, but have found no evidence that this was caused by neglect and it appears to have instead been from an acute medical condition.
“We will continue to monitor the welfare of the remaining horses and ask anyone with any extra information or concerns to call us on 0300 1234999.”
The RSPCA cannot take the animals without the permission of the owners.
The spokesman added: “The RSPCA can only act within the law.
“We cannot take horses without the permission of their owners or unless a vet has confirmed they are willing to support a case that an animal is suffering – which would then allow the police to remove the animals.
“This is not an isolated incident and the country is currently in the grip of a horse crisis with the RSPCA and other horse welfare charities struggling to cope with the numbers of abandoned, neglected and abused horses.
“We are stretched to breaking point with about 125 places at our equine centres and more than 500 horses in our care.”
One of those with concerns, who wished to remain anonymous, first voiced his worries a few years ago.
He said: “There are several groups of horses kept in this area.
“People are constantly contacting the RSPCA about their condition, but nothing ever gets done.
“We contacted the RSPCA a few years ago when they had vegetation woven into their tail hair.
“Now one has died, and it may be entirely innocent and natural causes, but there are a lot of people concerned for their welfare.”