Page 406 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Musculoskeletal system: 1.8 Soft-tissue injuries 381

VetBooks.ir These injuries are most likely a consequence of direct Diagnosis
trauma. Trauma and haematomata can also induce a Clinical examination
small, marginal lesion in the SDFT (see Paratendonitis,
ultrasonography is warranted to confirm the diag-
p. 345). Plantar ligament desmitis is encountered in a The typical deformity is fairly pathognomonic, but
much smaller proportion of cases with a curb-like nosis and evaluate the extent of the lesion and the
swelling. It is encountered in horses of all breeds, with tissues involved.
a predisposition in those with a sickle hock conforma-
tion. A curb-like appearance is observed in young foals Radiography
with dorsal collapse of cuboidal bones, causing a sagit- Radiography is advisable to rule out other causes or
tal deformity of the tarsus (see p. 36). damage to the underlying bones (i.e. calcaneus and
heads of the second and fourth metatarsal bones).
Clinical presentation
There is a typical convex deformity over the plantar Ultrasonography
aspect of the hock (Fig. 1.751). The swelling may be soft Subcutaneous and peritendinous tissue thickening
initially, but it is often firm in chronic cases. Lameness is obvious (Fig. 1.752). Haematomas may be visible
may be marked, particularly in cases with SDFT ten- as hypoechogenic tissue forming a crescent-shaped
donitis, but presents in a more low-grade, recurrent halo plantar to the SDFT and sometimes filling in
form in plantar ligament desmitis. Many horses do not the space between the SDFT and other underlying
appear to be lame, although it has been incriminated as structures (plantar ligament, DDFT). Vessels may
a cause of loss of performance in racehorses. be compressed or damaged. There may be an associ-
ated acquired bursa or calcaneal bursa distension in
Differential diagnosis acute cases, although most lesions tend to be more
Swelling involving distension of the calcaneal bursa, distal and not involve the tuber calcis.
fracture and osteitis of the calcaneus; in foals, tarsal SDFT lesions are typically focal hypoechogenic
bone collapse causing sagittal deviation of the tarsal and associated with marked tendon enlargement
bones should be considered. (Fig. 1.753). Focal lesions on the plantar or abaxial

1.752 1.753

1

Fig. 1.752 Longitudinal sonogram over the plantar Fig. 1.753 Transverse sonogram over the plantar
aspect of the calcaneus. The SDFT (circled) and LPL aspect of the calcaneus of a horse presenting with
(arrow) are normal, but there is marked thickening of curb. The SDFT (circled) is enlarged, with a focal,
the subcutaneous tissues (arrowhead), probably as a central and hypoechogenic lesion (yellow arrow),
result of repeated, mild trauma. as well as a peritendinous, hypoechogenic lesion
suggesting paratenon thickening (red arrow).
The LPL is normal. 1 = DDFT.