138 Canine Sports Medicine and Rehabilitation
units post‐tibial plateau leveling osteotomy
(TPLO) had decreased pain, swelling, and lame
ness with increased passive range of motion
when compared to sham‐treated dogs.
In addition to reducing inflammation, cryo
therapy may lessen pain through several other
mechanisms. Decreased tissue temperatures
have been shown to lower sensory nerve con
duction velocities (Herrera et al., 2011) and
increase both pain threshold and pain tolerance
(Algafly & George, 2007; Park et al., 2014).
Analgesia may also result via the gate control
theory of pain, with overstimulation of cold
receptors blocking the transmission of pain
signals to higher centers. Pain reduction may
also be attributable to the downregulation
of pain‐sensitizing inflammatory mediators
(Zhang et al., 2014).
While efforts have been made to assess the
ability of cryotherapy to address pain in animals
(Downer, 1978; Sluka et al., 1999; Corti, 2014),
these effects can be more easily measured in
human patient populations. Indeed, its use has
been shown to reduce the need for additional
pain medications following orthopedic surgery
(Ohkoshi et al., 1999; Barber, 2000; Kuyucu et al.,
2015). Cryotherapy has been shown to be
effective in reducing the discomfort associated
with osteoarthritis (Guillot et al., 2017), muscle
injury (Fonseca et al., 2016), fractures (Barca
et al., 2016), rheumatoid arthritis (Księżopolska‐
Orłowska et al., 2016), and surgical wounds
(Gatewood et al., 2017). Cryotherapy can also
reduce painful muscle spasms (Nadler et al.,
2004), possibly related to a decreased firing
rate of muscle spindle and Golgi tendon
organ receptors (Mense, 1978; Feys et al., 2005).
A reduction in electromyogram (EMG) activity
following cryotherapy has been demonstrated
as well (Macedo Cde et al., 2016). Finally, cold
therapy may limit development of post‐exercise
soreness (Brophy‐Williams et al., 2011; Fonseca
et al., 2016), helping to encourage patient par
ticipation and compliance.
Therapeutic effects on tissue protection
and healing
Cold application after injury can reduce the risk
of further tissue damage by decreasing cellu
lar metabolism (Merrick et al., 1999), which,
through decreased cellular oxygen demands,
can diminish secondary hypoxic cellular injury
(Merrick, 2002). In addition, Siqueira and col
leagues found that performing three 30‐minute
cryotherapy sessions for the 3 days following
muscle injury reduced the production of reac
tive oxygen species, indicating reduced oxida
tive stress (Siqueira et al., 2017).
Cold therapy offers clear protective and
healing benefits at the tissue and organism
levels as well. For example, temperature reduc
tion has shown a protective effect on micro
circulation in the area of injury (Schaser et al.,
2007). Additionally, Oliveira and colleagues
demonstrated that cryotherapy application
immediately following muscle trauma resulted
in a smaller area of damage as compared to
untreated muscles (Oliveira et al., 2006).
Cryotherapy may also decrease the risk of
compartment syndrome often associated with
skeletal muscle ischemic injury and closed soft
tissue injuries (Wright et al., 1989; Schaser et al.,
2007). Finally, cryotherapy can assist with over
all healing of the patient as a decrease in pain
alone can lead to earlier patient mobilization
(Bleakley et al., 2006; Song et al., 2016).Therapeutic effects on tissue flexibility
and joint ROM
Regaining muscle flexibility and joint ROM is
key to functional recovery. The therapist can
employ several techniques toward improving
both muscle flexibility and joint mobility
(Chapters 5 and 6) but they may involve some
discomfort for the patient. When working with
human patients, the procedure can be explained,
often resulting in better relaxation and subse
quent outcome of the treatment. In canine
rehabilitation, however, achieving and main
taining a relaxed patient during a potentially
uncomfortable treatment may be more diffi
cult. The therapist may experience greater suc
cess if cryotherapy is performed prior to these
techniques. For example, Park and colleagues
found that brief periods of local cryotherapy
(3 minutes) reduced uncomfortable stretch
sensations and increased the pressure pain
threshold of tight muscles (Park et al., 2014).
Larsen and colleagues showed that greater flex
ibility gains could be achieved with longer peri
ods (20 minutes) of icing prior to stretch (Larsen
et al., 2015). Lastly, cryotherapy may be effective