Front Matter

Chapter 7 Rehabilitation Physical Modalities 143

may be more effective than dry (Igaki et al.,
2014) although the impact of the canine
patient’s coat is unknown. When using a hot
pack, the patient should be positioned to
encourage relaxation while still permitting
access to the treatment area (Figure  7.8). If
needed, additional padding should be placed
between the patient and the pack to prevent
burns, and the skin should be checked fre­
quently. Recommended treatment duration is
20–25 minutes (Lin, 2003), although Millard
and colleagues found that 10‐minute applica­
tion was sufficient for heating up to 1.5 cm in
depth and no additional tissue heating had
occurred at 20 minutes (Millard et al., 2013).
Additional treatment time may be required
when treating overweight patients as adipose
tissue impairs heat transfer. However, there
may also be an increased burn risk as skin
temperature increases are greater in obese
patients (Petrofsky & Laymon, 2009). In the
canine rehabilitation setting, superficial heat­
ing is typically used before manual therapies
(soft tissue mobilization, stretching, passive
ROM, or joint mobilization—see Chapter  6)
are performed (Figure  7.9), or prior to active
exercise to improve ease of movement.

Precautions and contraindications

Caution should be used when heating over
areas of decreased circulation or open wounds,
in patients with inflammatory conditions, or
when treating sedated animals or those with
decreased sensation. Use of superficial heating

agents also carries a risk of burns or other

thermal tissue injury (Jabir et al., 2013; Cho

et  al., 2015). Contra indications include acute

inflammation, active bleeding, fever, and

applying heat over a malignancy.

Therapeutic ultrasound

Therapeutic ultrasound (TUS) uses sound

energy at frequencies greater than 20,000 Hz

to affect biological tissues through both ther­

mal and nonthermal mechanisms. Sound

waves are produced via the reverse piezoelec­

tric effect (compression and expansion of a

piezoelectric crystal). These sound waves are

essentially mechanical pressure waves and,

as they move through tissues, absorbed

energy is converted into kinetic energy. This

causes a chain reaction of molecules vibrating

and colliding into neighboring molecules.

Absorption is greatest in tissues with high

protein content.

Phonophoresis, a treatment that uses TUS

energy in an effort to deliver medications trans­

dermally, will not be discussed in this chapter.

It is worth noting that many medications that

are compounded with ultrasound gel may

effectively block transmission of sound energy,

resulting in a less effective treatment overall

(Cage et al., 2013). Therapists who use this

treatment should ensure that medications are

compatible with TUS. For additional informa­

tion, the reader is referred to the physical

modality textbooks previously noted (Cameron,

2013; Bellew et al., 2016).

Figure 7.8 Patient receiving superficial heat therapy via
hydrocollator pack in a relaxed position. Note the
additional padding between the pack and the patient.

Figure 7.9 Patient receiving superficial heat therapy

prior to carpal joint mobilization.