Thermal image of heat emission from the inside of the fetlock area. The affected site is circled and compared with the region on the other limb and a statistically significant lesion was found. Ultrasound examination yielded information on damage to the ligaments.
Thermal image of heat emission from the inside of the fetlock area. The affected site is circled and compared with the region on the other limb and a statistically significant lesion was found. Ultrasound examination yielded information on damage to the ligaments.

Thermography is a non-invasive technique, whereby a camera with a sensor measures the infra-red emissions from a horse’s body. Once the information is recorded, it enters the camera and the temperature variations are depicted in the display with different colors corresponding to different temperatures.

Essentially what we can see is the horse’s body, then we look at specific areas and compare them between one leg or one site and another. After images are recorded in the camera they are then downloaded into a computer that analyzes the data and generates a report which indicates the relevance of the temperature variations.

The reason that heat detection is important is because the presence of heat is considered one of the cardinal signs of inflammation. The human hand is able to appreciate, in some circumstances, a change in temperature of 1.0 degrees C, while this camera can detect changes down to 0.1 degrees C, a ten-fold improvement. In addition to heat, the camera will also appreciate cold areas. Heat or inflammation is generally a result from hemorrhage, external or internal trauma, tendon or joint inflammation and/or infection. Conversely, cold may be seen with decreased circulation, non-active swelling such as edema or in the presence of obstruction of blood flow.

Focal increase in heat from injured tendon.
Focal increase in heat from injured tendon.

In this image there is a white spot corresponding to intense heat at the site of injury. The tendon did not have significant swelling and the horse's lameness was discovered before further damage could occur. By visualizing this area early in the course of the lameness, an ultrasound exam identified swelling in the tendon and allowed for a successful plan to monitor and treat the area as the horse was brought back into work.

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