260 Canine Sports Medicine and Rehabilitation
dog. If a physis is injured, it can prematurely
close, resulting in a shortening or malformation
of the leg. This can limit or abrogate the dog’s
ability to have a performance or working career
(Harasen, 2003).
While physeal injuries can be caused by an
acute event, such as a fall or a blow to a limb,
chronic injuries to the physes also can occur
from overuse of young growing bones. Canine
sports medicine/rehabilitation professionals
have observed that agility dogs that are taught
to weave or jump at a young age and are
trained repetitively while young have an
increased risk of chronic injuries, particularly
to the spine, later in life. Agility dogs, particu
larly those of larger, more heavy‐set breeds
such as Golden Retrievers, that present with
career‐ending lumbosacral disease frequently
have a history of being eager, fast weavers that
were overtrained as young dogs. This condi
tion appears to be much less common in dogs
that begin intensive agility training when
physically mature. Overuse or repetitive
trauma injuries represent approximately 50%
of all pediatric sport‐related injuries (Valovich
McLeod et al., 2011). There is a significant need
for research to increase our understanding of
the effects of physically taxing sports on canine
athletes.
Research on the effects of resistance training
on young human athletes suggests that moder
ate strength training can be beneficial in chil
dren (Fedewa & Ahn, 2011; Gunter et al., 2012).
Coaches who place young athletes on strength‐
training programs must ensure that the athletes
are properly taught the appropriate skills, are
provided with a well‐controlled, progressive
program, and are not subjected to repetitive
stresses.
For endurance training such as long‐distance
running, the story may be a bit different.
Running depends on aerobic power—the abil
ity to transport oxygen from the air to produce
energy in the muscle cells. Endurance training
can increase aerobic power in adults by up to
30%. But in children, the maximum increase,
even with very hard training, is only about 10%
(Borms, 1986; Zauner et al., 1989). The cardio
vascular system of a preadolescent youngster is
simply not mature enough to adapt well to the
physiological stress of long‐distance running.
Furthermore, while long‐distance running
does not seem to harm the cardiopulmonary
systems of children, overuse or repetitive
trauma injuries represent a large percentage
of all pediatric sports‐related injuries
(Valovich McLeod et al., 2011). Again, matu
rity is an issue. Up to about age 16, the grow
ing cartilage in the long leg bones and
surrounding the joints is relatively soft.
Continuous foot‐to‐road pounding can easily
injure the cartilage during miles of training
(Loud et al., 2005). In addition, a child’s leg
bones can grow very rapidly, particularly
during puberty. When this happens, the mus
cles and tendons that span the joints stretch,
rather than grow. As a result, the tissue can
get very tight, like taut elastic bands, increas
ing the risk of injuries.
There are psychological considerations as
well. For many children, intense training
can lead to problems like anxiety and chronic
fatigue (Winsley & Matos, 2011). Such prob
lems can easily take the fun out of the activity
and could foster an unhealthy attitude
toward sport, exercise, and physical fitness in
general.
Bones grow and function the same, whether
they make up the skeleton of a child or a dog.
We can learn a great deal from studies that
have been performed in human athletes
because people can clearly identify where and
how much they hurt and can verbalize their
emotions about training. Hopefully, more
studies in dogs will be performed in the
future.
Guidelines for the types of exercise to which
puppies and growing dogs can be exposed are
provided in Table 10.4. These guidelines err on
the side of caution, preventing young dogs
from experiencing extremes of physical activ
ity because of the problems that can develop
in young adult and middle‐aged dogs that are
trained and exercised excessively prior to
the closure of growth plates. Some dogs are
driven to exercise even at young ages and will
push themselves beyond the limits of safety. Be
sure to set boundaries for your clients’ dogs
with the goal of increasing their longevity in
performance.