Page 730 - Adams and Stashak's Lameness in Horses, 7th Edition

696 Chapter 5

US frequently shows enlargement of the GT with seen proximally. In the longitudinal scan, the normal
focal or diffuse hypoechoic areas with loss of normal SDFT has a dense parallel fiber pattern. Deep to the
VetBooks.ir Mild thickening of the wall of the calcaneal bursa due to direction), is rectangular in shape, and is firmly attached
SDFT, the LPL is at full thickness (plantar to dorsal
fiber alignment when viewed in the longitudinal plane.
to the calcaneus. At this level, the DDFT is out of view
chronic distension with primarily anechoic fluid may be
identified. Infection and trauma tend to involve the medially and must be evaluated by placing the trans-
attachments of the GT, SDFT, and calcaneal bursa. The ducer plantaromedially. In fact, only 30% of horses in
GT and SDFT and the LDFT and TS should all be evalu- one study had injury of the LPL.
ated with US. The prognosis for athletic soundness in Curb was reported to be caused by excessive stress or
horses with chronic calcaneal bursitis and associated strain from race training (80 horses), direct trauma (11
osteolytic lesions of the TC is guarded. horses), previous injection (3 horses), associated injuries
(3 horses), and an apparent “bad step” or unknown
cause (13 horses). The most common reported form of
Curb
direct trauma was stall or wall kicking. Horses with LPL
The term curb describes a swelling along the plantar desmitis, SDF tendonitis, or DDF tendonitis or those
aspect of the calcaneus distal to the point of the hock/ with combined soft tissue injuries exhibited most pro-
tarsus but does not typically addresses etiology. While nounced lameness. Horses with curb are more likely to
desmitis of the long plantar ligament (LPL) can manifest have swelling and injury of peritendinous and periliga-
as a swelling in this region, it is not the only cause of mentous tissue and/or SDF tendonitis than injury of the
120
curb. It is felt that curb may result from excessive vio- LPL. Horses with severe SDF tendonitis, LPL desmitis,
lent tension or direct trauma. Trauma may occur from LDF tendonitis, or combined soft tissue injury received
kicking walls or tailgates in trailers and violent attempts long‐term rest (3 months) and controlled return to exer-
to extend the hock. In addition, there is some specula- cise, but they were the most likely group to do poorly or
tion that conformation may predispose to the develop- to remain lame. Diagnostic US examination may reveal
ment of curb. Lameness, if it occurs, is typically minimal that the swelling is due to peritendinous or periligamen-
and of short duration. Horses with persistent lameness, tous fibrosis, SDF tendinitis, DDF tendinitis, or LPL
particularly those with swelling more distal to the LPL, desmitis. Curb is primarily an injury of racehorses but
should be evaluated more carefully. Superficial digital does occur in nonracehorse sport horses. Within race-
flexor (SDF) tendinitis of the proximal metatarsus may horses, the STB is predisposed. Gait differences between
have a similar appearance, with swelling distal to the the STB and TB may account for this predisposition, but
calcaneus. Occasionally, a similar swelling exists with- conformation may play a role. Sickle‐hocked conforma-
out lameness. This swelling has a fluid consistency and tion is more prevalent in the STB breed and seems to
appears sonographically as a fluid pocket surrounding predispose these horses to the development of curb. It is
the SDFT. Drainage of the fluid may alleviate the problem, felt that overload or excessive strain of plantar soft tissue
but persistence of the fluid may warrant corticosteroid structures would be exacerbated in horses with sickle‐
injection. hocked conformation. Etiology of curb in the sport horse
While curb is primarily an injury of racehorses, and may be different than that in racehorses because direct
most commonly the STB racehorse, it does occur in non- trauma was a common etiology in nonracehorse sport
racehorse sport horses (Figure 5.99). US examination of horses. Horses with more severe lameness may have
this area reveals thin subcutaneous fibrous tissue layer, acute LPL inflammation and tearing due to violent exer-
the SDFT as a crescent shape, narrow in a medial to tion, trauma from kicking, and violent attempts to extend
lateral direction, and somewhat thickened from that the hock.

R TARSUS
DPOH CURB

A B

Figure 5.99. Horse with swelling along the plantar aspect of the fluid pocket surrounding the SDFT (B; arrows demonstrate a
calcaneus distal to the point of the hock (A; arrow). Often the swelling consistent with an organizing hematoma surrounding the
swelling has a fluid consistency and appears sonographically as a SDFT).