Front Matter

142 Canine Sports Medicine and Rehabilitation

through vasodilation (Nadler et al., 2004). This
effect has been shown when treating chronic
wounds as well (Petrofsky et al., 2007). More
recently, Neff and colleagues demonstrated that
superficial heating can even enhance blood
flow into areas with compromised vasculature,
such as tissues affected by peripheral artery
disease (Neff et al., 2016), by promoting capil­
lary growth (Kuhlenhoelter et al., 2016), further
supporting healing.
Xia and colleagues demonstrated an increase
in the metabolic activity with superficial heat­
ing as well as stimulation of cell proliferation
of in vitro human skin fibroblasts, believed to
represent a mechanism of improved wound
healing in vivo (Xia et al., 2000). Ito and col­
leagues noted similar findings using a thera­
peutic thermal environment (37 °C) to promote
articular chondrocyte metabolism and cell
proliferation (in vitro), information that may
be important in the treatment of osteoarthritis
(Ito et al., 2014).
Therapeutic temperature elevation may also
provide protection to damaged tissues during
the healing process. Khan and colleagues found
that providing 38 °C heating over skin graft
donor site wounds led to the expected increase
in local blood flow but also a significant increase
in lymphocyte movement into the tissues,
possibly indicating an enhancement of the
immunity within the wound (Khan et al., 2004).
Furthermore, Ikeda and colleagues found that
superficial heating increased subcutaneous
oxygen tension, a measure that correlates
strongly with resistance to infection as well as
improved wound strength (Ikeda et al., 1998).

Therapeutic effects on tissue flexibility
and joint ROM

Heat increases the viscoelastic properties of
connective tissues (Hardy & Woodall, 1998).
Superficial heating can therefore promote
improved flexibility and joint ROM (Petrofsky
et al., 2013) if the restricted ligament, tendon, or
joint capsule is located within 2–3 cm of the
surface. In humans, use of superficial heat com­
bined with stretching is more effective than
stretching alone (Funk et al., 2001; Robertson
et al., 2005; Nakano et al., 2012) although there is
also some evidence that active heating through
exercise may provide greater benefits toward

muscle flexibility (Rosario & Foletto, 2015). This

is worth considering when designing rehabili­

tation treatment plans for both human and

canine patients, especially if time is restricted.

Including superficial heat therapy as part of the

home exercise program (HEP) can also lead to

significant increases in active ROM (Petrofsky

et al., 2016a). Finally, heat application can be

helpful when stretching patients who have con­

tractures and/or spasticity due to neurological

injury, as shown with rats with spinal cord inju­

ries (Iwasawa et al., 2016).

Therapeutic effects on muscle strength

While superficial heat application has not been

shown to have direct effects on muscle strength,

a study by Petrofsky and colleagues showed

that patients with chronic knee pain who used

heat therapy prior to performance of a daily

HEP (in combination with in‐clinic therapy)

had significantly enhanced strength gains as

compared to the exercise‐only group (Petrofsky

et al., 2016a), likely related to improved comfort

and resulting increased compliance.

Considerations for clinical application

In canine rehabilitation, superficial heating

is  typically provided through application of

a hot pack. This can include moist heat

(hydrocollator) packs, gel packs warmed in

hot water or a microwave, or clay packs

(Figure 7.7). There is evidence that moist heat

Figure 7.7 Patient receiving superficial heat therapy

via clay pack over the hip, lateral thigh musculature,

and stifle.