Infrared Thermography (IRT) has been used in the equine industry for over forty years. But at its inception, there were issues with the significantly bulky and expensive cameras, poor image resolution/detail, and lack of standardization in both patient and environment preparation, which led some to believe the technology was defunct. However, as with computers and cell phones, there have been significant advances in both the infrared technology and cameras, and in the research, standardization, and utilization of IRT in the equine industry.
Infrared images are now widespread in equine magazines for product advertising, incorporated into pre-purchase exams and saddle-fittings, and appearing in national and international peer-reviewed journals and veterinary conferences.
DETECTING SURFACE HEAT
The infrared camera detects infrared waves that are invisible on the spectrum to our human eye, and converts them to an image we can see called a thermogram; this is different than night-vision, which amplifies ambient light. The infrared waves are seen as surface heat, and in biological systems, where there is increased heat, there is increased circulation. Increased circulation can be correlated with inflammation; likewise, cooler regions may also indicate problems with circulation or nervous system conduction.
The patient is used as its own control, as well as comparing images to “normals.” A change in one degree between two comparative regions is considered abnormal, and while the experienced human hand can feel changes at two degrees, a common thermal imager is sensitive to 0.04 degrees C.
Infrared thermography has advantages in the equine industry for being non-invasive and safe (no harmful radiation), quick to perform and well tolerated, affordable, and useful for:
- lameness localization
- shoeing and farrier applications
- product research
- infectious disease screening
- monitoring healing
- equine welfare and sports (anti-soring)
WORKING IN TANDEM
Thermography and nuclear scintigraphy (bone scan) are both considered physiologic imaging modalities. IRT recognizes metabolic changes, changes in circulation, inflammation, and nervous system conduction; bone scan shows increased radioactive isotope uptake in areas of active inflammation. Both modalities are typically followed by anatomic imaging, such as radiographs, ultrasound, and MRI to detect which specific structure is affected. Alone, neither anatomic nor physiologic is perfect….but together, these tools are synergistic.
Extreme inflammation RF foot related to an abscess
Overlay of IR image with digital showing asymmetries and inflammation related to infection and bruising
Patient with Navicular Syndrome (caudal heel pain), with excessive heel heat, and changes at the coronary bands and heels.
This case was identified as having acute on chronic navicular syndrome, after thermography identified abnormal patterning in the hooves and lower limbs, and anatomic imaging confirmed both osseous and soft-tissue changes. With a proper rehabilitation protocol that included rest, anti-inflammatories, integrative medicine, and trimming/shoeing support, the patient was able to recover and return to light work.
Appearance of laminitis on thermogram
A DIAGNOSTIC TOOL
Thermography is gaining recognition for its merits and is a very useful diagnostic tool for identifying patterns consistent with hoof and distal limb problems including laminitis, bruises/abscesses, ringbone and sidebone, shoeing and trimming imbalances, navicular syndrome and caudal heel inflammation, tendon and ligament injuries. Performance-limiting or career-ending conditions such as kissing spines, tendon/ligament problems, and soreness from poorly fitted saddles, hoof abnormalities, arthritis, and cervical injuries all produce patterning detectable with thermographic cameras.
Where the technology is less useful is if a problem is very chronic and intra-capsular or deep, for example a case with lameness of two years’ duration localized to the LF hoof. This is a case that would likely require an MRI to assess deeper internal structures in the foot – thermography can detect surface patterns, but does not penetrate and is also therefore not useful for small internal structures or those deep to thick muscles, early-stage pregnancy detection or internal tumors. However, thermography excels in providing a whole horse assessment, particularly identifying compensatory issues throughout the patient, as well as primary issues.
When used properly and interpreted with experience, it is highly sensitive, safe, affordable, and has a wide-range of uses well suited to the equine industry.
Joanna Robson, DVM, CVSMT, CMP, CVA, CSFT, CIT owns Inspiritus Equine, Inc., an integrative equine veterinary practice based in California. She is passionately dedicated to client education and promoting whole horse healing through unification of the professional veterinarian-farrier-trainer-saddler-nutritionist team. Dr. Robson is the author of "Recognizing the Horse in Pain - and What You Can Do About It," and is a well-known national and international lecturer on topics such as infrared thermography, saddle-fitting, understanding alternative medicine modalities, and anatomy and biomechanics. www.InspiritusEquine.com