514 Canine Sports Medicine and Rehabilitation
management, patient assessment, and report-
ing. Veterinarians should be aware that the
FLIR ONE camera designed for smart phones
and easily available and affordable to clients
does not provide sufficient resolution for
medical diagnosis.
How thermography works
Thermal imaging is a noninvasive, nonradiat-
ing, physiological diagnostic tool (Jiang et al.,
2005) that depends on radiant heat from
metabolism. Vasoconstriction from increased
sympathetic tone decreases regional blood
volume and therefore temperature; vasodila-
tion from decreased sympathetic tone or
inflammation increases local temperature. By
correlating pattern changes in temperature
with various diseases, degeneration, or injury
processes, thermography may provide a repro-
ducible diagnostic tool (Uematsu et al., 1988;
Ring, 2004; Diakides & Bronzino, 2008).
Thermal images provide absolute tempera-
tures (aT), and differences in temperatures of
similar areas or tissues (∆T) are noted. A differ-
ence of more than 1 °C between areas is con-
sidered significant (Turner et al., 1986).
Thermal imaging cameras use high‐resolution
lenses that gather infrared photon energy
packets into high‐speed and high spatial reso-
lution focal plane array detectors (Volmer &
Mollman, 2010). Images are stored as digital
jpeg and video files.Using thermographyThermal imaging does not replace, but rather
augments, a thorough physical examination,
and its use as a physiological imaging tool inte-
grates well with anatomic imaging such as
radiography, CT, MRI, and ultrasonography.
Though hot spots generally indicate pathologi-
cal changes, cool areas also can indicate abnor-
malities (Devereaux et al., 1986) (Figure 20.12).
Environmental factors such as radiant heat
sources, lights, and exposure to either direct or
indirect sun as well as coats, collars, and har-
nesses must be controlled during thermal imag-
ing. Fans, breezes, water, topical medication, or
uneven hair thickness can create artifacts.
Dampness can cause an evaporation artifact for
several hours after a bath.
If the environmental temperature is similar
to the temperature of the dog, it will be impos-
sible to discern usable heat patterns. In very
extreme cold, thermoregulatory vasoconstric-
tion may mask all but the most severe inflam-
matory changes (Figure 20.13).Figure 20.12 Lateral thermal image of an agility Doberman recently involved in a collision with another dog and
demonstrating pain to touch in the thoracolumbar region. The range of temperatures read in the scan is shown on the
right side of image. The greener areas in the dorsal, lumbar areas were edematous and painful to touch, indicating
probable subcutaneous bruising.