In one village, 130 of 150 animals have reportedly contracted the disease.
Authorities suspect it may have come into the state from Uttar Pradesh following the arrival of horses from that area.
A major outbreak could have serious economic consequences for the region, where equines are used extensively for transport.
A military veterinary unit is reportedly in the area and, assisted by state officials, is providing free medication and helping treat affected animals.
The disease is thought to have spread to other nearby villages, despite efforts to contain it. Authorities are warning people that they pose a greater risk of spreading the disease than horses.