Three foals have been found in south east Northumberland tied to railings and left without water.
Northumberland County Council is warned horse owners who abandon their animals that they may face prosecution for causing suffering or neglect.
Council officers were alerted to three foals which had been left tied to railings at the Grace Darling academy in Newbiggin.
They had been left without water, and one foal had become tangled in its tether, and was in danger of breaking a leg.
The foals were taken out of Northumberland to a welfare centre, where two of the animals were found to be in poor condition.
The council is appealing for help in identifying the owners of the horses.
Anyone with any information is asked to contact the Environmental Enforcement Team, in confidence, on (01670) 627000.
Coun Ian Swithenbank, policy board member for streetcare and environment, said: “Owners should know that we will not tolerate animals being abandoned with no regard to their welfare.
“We may seek to prosecute those who neglect animals or cause them suffering.”
The council has taken firm action to address the problem of horses left to graze on council-owned land.
“In the last year, 50 horses have been uplifted from unlawful grazing sites.
“If they are not claimed by their owners and a fee paid, they have been re-homed wherever possible.”
Two authorised horse grazing sites opened in Newbiggin last December, at Store Farm and East Lea, and work is on-going to identify another site in Ashington.
The routine tethering of horses is an unacceptable practice and is discouraged by the council, therefore animals authorised to graze under licence will roam free within the confines of the paddock to which they are allocated.