The case had been unusual in that it occurred at the height of summer.
"Since June 2011, there have been 14 horses confirmed with Hendra virus and for the first time outside of a laboratory a dog tested positive for Hendra virus antibodies," Symons said.
He said horse owners should remain vigilant against Hendra virus.
"It is possible for Hendra virus infections to occur at any time throughout the year, so it is very important horse owners practice good biosecurity on their properties to protect themselves and their animals.
"If horse owners notice any signs of illness in their animals, they should contact their local veterinarian."
Symons urged horse owners in Hendra-affected areas to complete a survey, which would help Biosecurity Queensland improve its understanding of issues around the disease.
"The survey is already providing valuable information for both Biosecurity agencies in Queensland and New South Wales," Symons said.
"There has so far been a good response, with more than 750 horse owners completing the survey across Queensland and New South Wales.
"But we need feedback from more horse owners. Understanding horse owners' husbandry, property management, and feeding practices provides valuable information in understanding the transmission of Hendra virus. Every horse owner's feedback is important."
Biosecurity Queensland was focused on learning more about the virus to ensure a safer environment for animals, horse owners, vets and the community, he said.