On Thursday, Jirawan Pluangkratok, a pig raiser in Chokchai district, said two more of her herd had died of the disease, bringing the total to 10.
The Department of Livestock Development has banned unauthorised transport of pigs in Nakhon Ratchasima province until the disease is identified.
Meanwhile, provincial livestock officials have guaranteed Jirawan compensation of Bt50,000 if she culls her entire herd.
Blood samples from the dead animals have been collected but the initial examination failed to clarify the cause of death.
The samples have been sent to the Northeastern Veterinary Research and Development Centre in Surin province for further investigation.
Nakhon Ratchasima was placed on alert last year after an outbreak of African swine fever in Vietnam and China led to the culling of millions of hogs.