The disease was first found in Nakhon Ratchasima but has now spread via mosquitoes, gnats and gadflies to other parts of the country, killing hundreds of horses, as well as zebras, camels, donkeys and mules.
Equines infected with the African horse sickness (AHS) virus will show symptoms of listlessness, no appetite, swollen eyes and fever exceeding 38.5 degrees Celsius.
Owners of animals should contact local livestock officials within 12 hours if their animals show any symptoms of AHS.
An official investigation showed the source of the infection came from horses imported from Africa. A ban has been placed on transport of equine stock out of areas where AHS has been found.
Last week the Department of Livestock Development and Thailand Equestrian Federation acquired AHS vaccines to help prevent further spread of the disease. It also urged owners to protect their horses and equines by erecting mosquito screens.