Front Matter

Chapter 12 Disorders of the Canine Thoracic Limb: Diagnosis and Treatment 299

nutrition, and genetics. Overnutrition, such
as an excess of calcium, has been found to
disrupt endochondral ossification and may
be the cause for shoulder OCD (Hazewinkel
et al., 1985; Dammrich, 1991). The second fac­
tor that contributes significantly to shoulder
OCD is trauma to the joint. Repetitive and
concussive impacts commonly experienced
by performance and working dogs likely
increase the prevalence of shoulder OCD in
that population.

Diagnosis

Slight to moderate lameness is common ini­
tially and many clients will not immediately
notice the change in gait. When clients do start
to notice lameness, it is not unusual for them to
report it only as a unilateral lameness in the leg
with the most severe symptoms. Lameness is
reportedly worse after exercise, and stiffness is
commonly reported after rest. Dogs will exhibit
a shortened stride length at both a walk and a
trot, and occasionally some will completely
offload the painful limb. Palpation typically
reveals pain along the caudal humeral head
and during shoulder extension and flexion. A
click can sometimes be noted during hyperex­
tension of the shoulder and is likely associated
with the coexistence of degenerative joint
changes. Muscle atrophy is generally noted in
long‐term or severe cases. Additionally, it has
been noted that the pain and lameness experi­
enced is often predictive of the size and location
of the OCD lesions. Dogs with a unilateral OCD
lesion located caudocentrally on the humeral
head showed a persistent lameness that did not
occur when the lesion was located caudomedi­
ally (Olivieri et al., 2007).
Radiographs can help to reveal OCD lesions
that may appear as a surface cavity and
cause  the surface of the subchondral bone to
seem flattened and/or abnormal in shape
(Figure 12.5). Rarely, OCD lesions are not
revealed by radiographs. In these cases, needle
scope or musculoskeletal ultrasound is recom­
mended to rule out OCD, especially for young
dogs with shoulder pain and lameness that is
indicative of shoulder OCD. Musculoskeletal
ultrasound, although not a strong modality
for  diagnosing shoulder OCD, may reveal
irregularities around the humeral head.

Treatment

Medical management consisting of NSAIDs and

restricted activity may benefit a small number of

dogs who present with mild OCD lesions, but

most cases will require surgical treatment.

Arthroscopy of the joint allows for removal of the

osteochondral flap, debridement, and  stimula­

tion of fibrocartilage formation. Fibrocartilage

formation within the lesion can be encouraged

through abrasion arthroplasty, microfracture, or

forage. Frequently, the flap fragments or breaks

free entirely, which may cause secondary condi­

tions such as bicipital tenosynovitis. On rare

occasions, the flap is unable to be located and is

reabsorbed (Olivieri et al., 2007). Arthroscopy is

minimally invasive, allows for extensive explora­

tion of the  joint, and allows for simultaneous

bilateral treatment. Arthrotomy is not preferred

as it may require a second surgical procedure

should the flap not be found caudally. In severe

cases with  large lesions and/or severe joint

inflammation, consideration may be given to

biological therapies to improve healing and

decrease inflammation (Mokbel et al., 2011).

One author (SC) recommends follow‐up

to  arthroscopic treatment consisting of eight

biweekly intramuscular injections of polysulfated

glycosaminoglycans (PSGAGs), lifelong oral joint

protective agents, and weekly rehabilitation

therapy to include manual therapy, physical

Figure 12.5 Radiograph showing shoulder

osteochondritis dissecans lesion (arrow).