Authorities in Western Australia (WA) are working to determine what’s causing small, round lumps in horses mouths on two properties in that state.

In a statement updated July 2, the Department of Agriculture and Food, WA, said officials have "taken samples from eight horses that have resided at two related properties … to identify the cause of mouth papules (small, solid rounded lumps) in the horses. The papules were reported by a private veterinarian attending to the horses.

"Testing has already ruled out the main virus of concern, vesicular stomatitis, and further testing is under way to determine the cause of the papules," the statement continued. "Preliminary testing suggests the lumps might be a response to a viral infection. The department is working with the veterinary clinic involved to finalize a diagnosis."

Area horse owners are urged to contact their veterinarian if they notice any unusual signs on their animals