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Yesterday a group of us from The ISCP attended a course in Veterinary Thermology in Cheshire, UK, and thoroughly enjoyed learning about this fascinating technology. It was taught by Sophie Gent, founder of SyncThermology, whose team uses their skills on humans, domestic pets, horses, and zoo animals and works in tandem with doctors and vets.

What is thermology?

The scientific term is Digital Infrared Thermographic Imaging (DITI). A sophisticated thermal imaging camera converts infrared radiation (IR) from the skin’s surface into electrical impulses which are visible as colours. The human or animal is scanned by the camera and the images are transferred onto a computer for interpretation. Infrared radiation is electromagnetic radiation with wavelengths longer than visible light but shorter than radio waves: it’s invisible heat. In our bodies it’s our metabolism that produces infrared.

Interpretation is the key, and it’s extremely complex. In a nutshell, the hotter areas (in the red spectrum, and white) in the scans show inflammation and the colder areas (in the blue spectrum) flag up neurological issues, but there’s a lot more to it than that. For instance, a blue area (cold) shows a nerve issue and dark blue/black shows vasoconstriction, but hot areas may also show where the animal is over-compensating and over-using a limb to avoid putting pressure on the limb where pain is present, as well as areas where pain is present.

DITI can’t photograph structure or anatomy. It measures activity in the autonomic nervous system (the parasympathetic and sympathetic nervous systems) and detects inflammatory and neurological processes. It also measures any interruption of homeostasis, and autonomic function and disease.

Symmetry is important when undertaking DITI scans. It can skew the results if the animal is scanned at odd angles, so a camera angle of 90 degrees, with each area framed in a square and with each side of the body scanned in exactly the same position, is necessary.

How does it work?

Inflammation at any tissue depth is recorded by sympathetic nervous system fibres or the neurological supply to that area. The neurological information is processed by the central nervous system, causing a sympathetic response in the area of the skin that corresponds to the affected site. Hyperthermia (excess heat) is due to a decrease in sympathetic motor tone.

Thermography only records skin surface temperature from a 5millimetre microdermal circulation, but areas of heat that show on the scans may not actually feel hot on the skin’s surface because there’s no direct conduction of that heat to the skin.

Thermal imagining shows objective results relating to the physiology of pain, pathology, injury, and dysfunction in the body, irrespective of the depth of the disorder. However, it is not about ‘hot spots’. The most important part of interpretation is pattern recognition.

Ideally, animals should be scanned when well to obtain a baseline scan, so that comparisons can be made when the animal or human is ill. During health, the image patterns on both sides of the body are symmetrical, which are consistent and reproducible, so changes in pattern are immediate indicators of an issue.

Thermology is not used as a diagnostic tool in itself, but is used in tandem with conventional diagnostic methods.

Environmental and other influences

Thermal imaging cameras are extremely sensitive to environmental factors such as heat, cold, water, etc., and these environmental factors create what is called ‘thermal drift’, which influences the scan results. So, rain, light (patches of sunlight), wind, cold, mud, sweat, slobber, and whether the animal has been wearing a coat all influence the results.

Certain treatments, such as sedation, nerve blocks, steroid injections, medications, physical therapy, bandages, casts, and exercise beforehand also affect scan results

What does thermography show?

DITI is not a picture of pain (as is commonly thought) but is a picture of autonomic dysfunction which correlates well with regions of pain. DITI is a window into the autonomic/sympathetic nervous system which records, via somocutaneous reflex, the sympathetic response to pain and injury.

One of DITI’s biggest contributions to medicine is the ability to detect post traumatic pain and sympathetic nervous system maintained pain syndromes which can occur after minimal injury.

Who interprets the results?

The thermographer must collect the data correctly for it to be useful, as the interpretation is dependent on the skills of the technician. It can then be read by the thermographer, and the medical doctor or veterinarian.

Applications for DITI

DITI is used for detection of pain, injury, joint changes, arthritis, fibromyalgia, tendon and ligament conditions, post-operative healing, disease, auto-immune disease, thrombosis, and tumours. In humans, it is used with great success for breast cancer screening because it detects breast changes long before an x-ray or mammogram can show these.

DITI is very helpful for evaluating complaints that may be related to changes in behaviour. Those of us who work professionally with dogs always ask about known health issues, and advise a veterinary check in the case of sudden changes in behaviour, as these may be caused by pain or an undiagnosed health issue.

DTI is very useful for preventative care because it can detect dysfunction at a very early stage, and can detect abnormalities two to four weeks before structure lesions are present. DITI’s ability to measure inflammatory processes helps to localise initial stages of breakdown so can be used for preventative as well as detective care.

DITI can be useful for monitoring recovery. It shows the response to treatment by objectively measuring inflammatory and neurological patterns over a period of time.

Baseline scans of a healthy body are important, because any subsequent changes can be detected well before these would show up on diagnostic instruments such as x-rays, MRI scans, etc. A full body equine scan takes 90 minutes, and a full body canine scan takes 40 minutes.

My personal experience

Over three months ago, I bought a small thermal imaging camera that attaches to my smartphone. The aim was to monitor pain levels in Skye, my lurcher, who has numerous serious health issues and is on a great deal of medication, including three different pain relief medications. I found it so fascinating that I booked a place on the SyncThermology course to learn more about how to use it effectively.

Although my camera was comparatively cheap (around £200, whereas the thermal imaging cameras used by SyncThermology cost around £17,000) and doesn’t have the high level of accuracy needed for professional use, I’ve found it very helpful. Scans before and after medication have shown me whether the medication is working, and whether it continues to work for the duration of hours before the next dose is due, and I’ve shared the photographs with my vets so that we can build up a picture of progress and deterioration. This, in conjunction with blood and scan results and observing Skye’s signals of discomfort and pain, has enabled us to know when we need to increase medication dosages, and has certainly kept his quality of life good for far longer than was expected.

However, there is a big however. Interpretation of results is complex with a professional grade thermal camera, and extensive training in the technology is needed. The results from these cheaper cameras aren’t as accurate, though Sophie Gent showed me how to use it for greater accuracy, and it’s vital that any modality is used alongside veterinary care. If you’re considering investigation through thermal imaging, please contact Sophie at SyncThermology to arrange for this to be carried out professionally.