In the 40 years Jim Stenhouse has been a vet, diagnosing a lame horse has always challenged the Queenslander.
More than 10 years ago, in his quest to better understand and detect one of the most common, and often costly, injuries in horses, Dr Stenhouse built a small thermal-imaging device.
The unit was crude, but when he used it to examine horses and athletes he discovered it could observe things - stress fractures and inflamed tendons - a visual examination could not pick up.
In the past decade, thermal imagers have improved and dropped in price and size, and now they are used by the military, in airports and in some fields of medicine.
Now a University of Sydney professor of animal behaviour and animal science has twigged to the potential of thermal imagers to study the eye temperature of horses.
Studies on cattle have found a correlation between an increase in eye temperature and an increase in salivary cortisol, a hormone released when the animal is distressed.
''We're interested to verify whether eye temperature is a proxy for physiological distress in horses,'' said Paul McGreevy.
''We need hard data to state with confidence how well any animal is faring,'' Professor McGreevy said.
Thermal imagers detect radiation, which is given off by any object above absolute zero degrees, and so can be used to compare differences in temperature between two regions.
This week, Dr Stenhouse and Professor McGreevy used handheld thermal imagers to examine three horses from the NSW Mounted Police Unit.
''This is the first time a university has decided to look closely at thermal imagers,'' said Dr Stenhouse, who consults for a firm that makes the devices.
While blood and saliva are often used to measure cortisol, the collection process could unnecessarily distress the animal and bias the results, Professor McGreevy said.
Thermal imaging was non-invasive and could be used at some distance from the animals, he said.