Thermal Imaging for Veterinarian Applications

The infrared heat that an animal emits from its body can be "viewed" with an infrared camera. The heat patterns that can be seen show a trained practitioner how the blood flow is normal, or abnormal, in a particular animal. Blood flow can be either increased or decreased, both indications of health problems.  

Physiologic imaging is a function of metabolic action. Physiologic images can change and might appear prior to anatomic disruption. Thermography (or thermal imaging) is considered physiologic imaging because as the animal's metabolism changes. For example a sore tendon heats up, that fact can be discerned.

Equine thermography

Thermography is a qualitative assessment of temperatures. The infrared camera measures temperature automatically and shows an thermal image with different colors for different temperatures. A "hot spot" indicates inflammation or increased circulation. Hot spots generally are seen in the skin directly overlying injury. A cold spot is a reduction in blood supply usually due to swelling, thrombosis, or scar tissue.

There can be "artifacts" found when using a thermography camera, so experience is a key to diagnosis. If legs have been wrapped, or blisters or liniments have been used, they will show up as areas with increased heat. Thermal symmetry is the rule - you compare one anatomic area with the same area on the other side (i.e., outside foreleg to outside foreleg).

Inflammation

Thermography can be used to determine if there is inflammation in an area that was sore on palpation, or to detect an area of increased blood flow when there is no specific pain or signs (subclinical inflammation). Most horses don't have just one problem associated with lameness. Thermography also helps in detecting the secondary areas with problems.

It has been noted that tendons and joints will show inflammatory changes as much as two weeks before clinical lameness is apparent.

Muscle injury

A very valuable use of thermography is in detecting muscle injury. It locates the area of inflammation associated with a muscle or muscle group. It shows atrophy before it becomes apparent clinically. Atrophy is seen as an area of consistent decrease in circulation when compared to the opposite side.

Nerve injury

Nerve injury due to direct trauma or secondary to another injury or disease can affect blood flow and can be visualized with thermography.

Preventive medicine

Thermography also can be used to assess the vasculature and blood flow to tissues before and after exercise. Other uses include pre-purchase examinations, saddle fit, a training aid to avoid injury, pre-race examinations, hoof balance, following tendon healing after injury etc. As can be seen, there are many different uses for this non-invasive, but reliable diagnostic tool.