Horses are warm-blooded animals that generate heat and regulate their body temperature. Based on these characteristics veterinarians seek to study the health of these animals and detect lesions. Thermography detects hot spots indicating an increase in blood circulation, which in turn can be considered a symptom of damage or disease (ex: one of the signs of inflammation is the increase in temperature). They also detect problems of bad or poor circulation. Is, therefore, an ideal tool for helping the diagnosis of lameness. The basic principle of this technique consists in the transformation of this heat generated by the body in images, with a wide range of gamma colors that reflect different emissions of heat.

Thermography can be described as a non invasive technique that measures infrared emissions, temperature, of the surface of a foreign body (or object). The result is a graphical representation of the temperature of the surface of a body (images).

In the last few years and with technological advances that had been produced there have been appearing in the equine market a wide variety of highly sophisticated diagnostic tools which include thermography. Equine thermography has increased in popularity recently due to an improvement in equipment, improvements in thermal cameras and in image processor software.

These advancements have finally made thermography increase its importance, by daily making its way into clinical practices as other techniques did in their time, such as radiography.
Its importance can be assessed from three different points of view:


- As a complementary technique for diagnosis. Its role in diagnosing many diseases and lameness is essential now that the key to its success is that it is able to detect damage in tissues, bones... before clinical signs are manifested.
It does not reveal the pathology specifically but facilitates the location of the increase (inflammation, injury) or decrease of heat (reducing blood flow or vasomotor tone). In its function as a diagnostic tool is where more professional opportunities are observed at up to now.
- For closely monitoring the progression of the injury and the healing process;
- Lastly, from the research point of view, we have its more innovative use that consists in the detection of illegal processes used to improve performance in sporting events.


To this day this technique is considered as an innovative diagnostic tool, it was apparently discovered by Hippocrates a thousand years ago, when they observed that when mud was applied on their patients it dried at different speeds depending on the area of the body where applied.
It was used for the first time in veterinarian medicine 35 years ago (in hospitals and universities).


Basic Grounds


Bases of the Technice


In the past, thermography was divided into methodology of "contact" and "no contact". Thermography of "contact" was based on the use of liquid crystals of a deformable base, which changed their form depending on the temperature that they were in contact with. The color of the crystal represented a determined temperature.
But finally this technique fell into disuse because it had many problems in the application over the bodies in which we will not go into. After there existed two techniques of "no contact": "cold" and "not cold". The "cold" technique uses a detector of infrared radiation to measure temperature.


The camera or detector are paired with a cathode ray tube and the intensity of radiation is converted into an electrical signal. This signal is displayed in the final images in black and white, passing through the scale of grays. The hottest areas are the whites and the cooler areas are the blacks, but thanks to the incorporation of a microchip, the white will be seen as red and the dark black blue being, therefore, the classic thermogram.


The main difference with the "not cold" technique is that the latter is composed of a series of detectors, is less fragile and more portable, although they are less sensitive than the "cold" to temperature changes.
Preferences vary, that is, there are authors who prefer the "cold" technique and there are those who prefer the "not cold" technique.


All the bodies and objects emit infrared radiation proportionately to their temperature, which are detected by thermal cameras. And where do we locate infrared radiation? To locate these radiations it would be advisable to do a quick review of the electromagnetic spectrum of all the wave lengths known so far, on a scale from the shortest to the longest are: gamma rays, x-rays, ultraviolet light, visible light (the only one that perceives humans), infrared, microwave and radio waves. These radiations can be absorbed, emitted, reflected or transmitted by a body/object. Radiation can be absorbed, emitted, reflected or transmitted by a body/object. But thermal cameras generate images that are based on the amount of heat generated, rather than reflected.


Infrareds can be optically focused, collected and transformed via detector arrays to an electronic signal. These devices or detectors, found within the camera, are composed of temperature sensitive material: barium, strontium and titanium; and they possess pyroelectricity properties.
These two features allow different temperatures to be generated through the body to reach a circuit inside of the apparatus in the form of a Pyroelectric signal, there it generates an electrical signal that can be transferred to another circuit where it is transformed into a visual signal which in turn reaches the software through which the images finally appear. A complicated path that we as veterinarians have no interest in and will leave in the hands of technicians and engineers, because in short, seeing the technique from a more clinical point of view which is our expertise and less physical of all prior we could summarize as follows:


An animals body is continuously generating heat, which is dissipated through the skin by radiation, convection, conduction, and evaporation. This is due to that the skin is generally 5°C colder than the rest of the body whose temperature is 37°C. The skin acquires a temperature from the local peripheral circulation and metabolism of the tissues, and both are responsible for the existence of a thermic pattern, which is basic for thermographic interpretation. Comprehension of this pattern is critical for the interpretation of these clinical cases; We must have direct cognition that the metabolism of the tissues is constant, and therefore, variations in the temperature of the skin are due to local perfusion, where we find that the veins have a higher temperature than the arteries because they drain metabolically in active areas. It is clear that the circulation and blood flow are what lead to thermic patterns. Within this pattern the thermography detects hot spots indicating increased circulation, and cold points that indicate poor or bad circulation. This terminology as we will see in continuation is for the interpretation of the images and to reach a diagnosis.

<< Start < Prev 1 2 3 Next > End >>