Page 1044 - Adams and Stashak's Lameness in Horses, 7th Edition

1010 Chapter 9

Table 9.2. Frequency of therapeutic injections performed over In the previously described western performance
a 7‐year period on 17,458 horses in a western performance horse demographic review, the fetlock joint was blocked
VetBooks.ir most frequently medicated synovial structure (N = 912;
equine sports medicine practice.
for diagnostic purposes in 239 cases and was the sixth
Table 9.1). Interestingly, the frequency of medicating to
medication
Synovial structure Frequency of fetlock joint with interleukin‐1 receptor antagonist pro­
tein (IRAP) was second only to the femoropatellar joint
(Josh Donnell, Unpublished data).
Tarsometatarsal joint 7,183 (28.8%)
Femoropatellar joint 5,133 (20.6%) PROXIMAL SUSPENSORY DESMOPATHY
Distal intertarsal joint 4,970 (20.0%) Suspensory desmopathy of the fore‐ and hindlimbs is
frequently encountered in western pleasure horses, albeit
Distal interphalangeal joint (forelimb and hindlimb) 4,480 (18.0%)
commonly with differing presenting histories. In the
Medial femorotibial joint 960 (3.9%) western performance practice demographic review, fore­
limb and hindlimb proximal suspensory analgesia was
Fetlock joint (forelimb and hindlimb) 912 (3.7%) pursued 648 and 575 times, respectively (Table 9.1).
Horses subsequently diagnosed with hindlimb proxi­
Carpal canal 897 (3.6%) mal suspensory desmopathy often present with a his­
toric hindlimb lameness that improves for 2–3 weeks
Sacroiliac joint 807 (3.2%)
following hock injections. Following the transient
Digital tendon sheath (forelimb and hindlimb) 650 (2.6%) improvement, however, the lameness returns and seems
exacerbated with work in soft, deep ground. Trainers
Navicular bursa 355 (1.4%) and riders also usually describe a lack of hindlimb pro­
pulsion, but this observation is not specific for only
Lateral femorotibial joint 338 (1.3%)
hindlimb suspensory desmopathy. The lameness is not
Carpus 332 (1.3%) consistently worsened when the hindlimb is on the
inside vs. outside of the circle and is broadly character­
Scapulohumeral joint 221 (0.9%) ized by a decreased cranial phase of stride and an unwill­
ingness to push during late stance phase. Once the
Tarsocrural joint 167 (0.6%) lameness has been localized to the proximal metatarsal
region in accordance with ruling out the distal limb,
Femoropatellar, medial femorotibial, and lateral 126 (0.5%) standard radiographic evaluation of the tarsus is typi­
femorotibial joints
cally pursued, followed by both weight‐bearing and
Pastern joint (forelimb and hindlimb) 113 (0.4%) non‐weight‐bearing ultrasonographic evaluation of the
proximal suspensory ligament as previously described. 6,7
Bicipital bursa 87 (0.3%) Commonly observed pathologic changes include liga­
mentous enlargement (desmopathy), osseous remode­
Cervical facet (total) 70 (0.2%)
ling (enthesopathy), fascial thickening (fasciitis), and
Cervical facet (C3–C4) 22 (<0.01%) loss of fat/muscle/fiber definition assessed with off‐angle
imaging. Ligamentous enlargement and osseous remod­
Cervical facet (C4–C5) 20 (<0.01%) eling of the plantar aspect of the third metatarsal bone
(Figure 9.55) singularly or in combination remain the
Cervical facet (C5–C6) 11 (<0.01%) most consistent, subjective findings in western pleasure
horses. However, a portion of acutely lame horses with
Cervical facet (C2–C3) 10 (<0.01%)
suspected suspensory injuries show no ultrasonographic
Total therapeutic injections 24,910 evidence of abnormalities. The importance of contralat­
eral limb comparisons cannot be overemphasized, per­
mitting the clinician to more easily evaluate subtle
Source: Josh Donnell, Unpublished data.
changes that may otherwise go undetected. Of the 1,728
ultrasonographic evaluations performed in the practice
demographic review, the forelimb and hindlimb suspen­
FETLOCK OSTEOARTHRITIS sory ligaments were the most frequently evaluated
anatomic structures with 871 and 365 exams performed,
Similar to the racing Thoroughbred, the western respectively (Josh Donnell, Unpublished data).
pleasure horses experience pathologic manifestations Horses subsequently diagnosed with forelimb proxi­
due to the chronic, repetitive forms of loaded exercise mal suspensory desmopathy commonly present with an
that they undergo. Condylar fractures are far less com­ acute lameness following a period of uncontrolled
mon in the western pleasure horse compared with the (excessive) lungeing or exercise. Alternatively, horses
racing Thoroughbred, but osteochondral fragmentation, present with an acute‐on‐chronic, insidious forelimb
synovitis, and eventual osteoarthritis with varying levels lameness that worsens with work. A common complaint
of articular damage, sclerosis (Figure 9.54), and bone for these horses is not “holding ground” with the limb
marrow edema are commonly encountered in western on the outside of the circle. Regardless of the history, the
pleasure horses. lameness is usually exacerbated with the limb on the