Page 389 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

364 CHAPTER 1

VetBooks.ir on palpation in acute cases. Clearly, most signs are 1.720
related to the associated tenosynovitis.

Differential diagnosis
Tenosynovitis, cellulitis, oedema and congestion of
the palmar veins should be considered.

Diagnosis
Clinical examination
Careful palpation may reveal some thickening and
pain over the affected area.

Radiography
Radiography is useful to eliminate other causes of
swelling in the palmar fetlock (e.g. fractures of the
sesamoid bones). There may be entheseous new bone
on the palmar abaxial aspects of the PSBs.

Ultrasonography Fig. 1.720 Transverse sonogram over the palmar
This is the diagnostic technique of choice. It will usu- aspect of the fetlock. The normal palmar annular
ally demonstrate the presence of tenosynovitis. The ligament is a thin, fibrous band (bracket) with fibrillar
PAL is visible as a thin band of tissue with a trans- organisation, lying directly over the palmar aspect
versely oriented fibre pattern that covers the palmar of the SDFT (yellow double arrow). Note the barely
aspect of the SDFT. It should measure <2 mm in visible synovial tissue between the tendon and the
thickness in an average 500 kg horse (Fig. 1.720). ligament (red arrow) and the thin subcutaneous tissue
The ligament may be thickened in association (arrowhead).
with tenosynovitis or as a result of chronic trauma
(Figs. 1.721, 1.722). Haemorrhage may be present Management
initially in or around the PAL. In chronic cases, dif- If a haematoma or subcutaneous thickening is
fuse fibrosis will form a thick layer of echogenic tis- noted, rest, local anti-inflammatory treatment
sue that makes it difficult to identify the PAL and (e.g. cold-hosing, ice packs) and bandaging until the
may extend to the palmar mesotenon of the SDFT, symptoms resolve are usually all that is necessary.
creating a continuous echogenic layer from skin to Tenosynovitis should be approached as described
tendon. earlier (see p. 355). In most cases, thickening of the
Entheseopathy is visible as local thickening on PAL responds well to conservative management and
the abaxial aspect of the PAL and irregular bony treatment of the associated tenosynovitis.
insertion (Fig. 1.723). Ultrasonography shows In chronic cases it is likely that fibrosis and thick-
that the large majority of suspected PAL syndrome ening of all the tissues affect the function and cause
cases are due to synovial membrane thickening reduced flexion and pain. In these cases, transection of
(Fig. 1.724). It is likely that thickening impairs the PAL (PAL desmotomy) may provide some relief.
the tendon movement through lack of mobility The surgery is best performed tenoscopically, as this
rather than through compression. Subcutaneous will allow accurate assessment of the sheath integrity
tissue thickening is visible between the echogenic and, if indicated, a partial synovectomy to be per-
epidermal layer and the PAL (Figs. 1.725, 1.726). formed. The ligament is severed using a retrograde,
In acute cases, a haematoma may be visible at this curved tenotomy knife (‘hook blade’), arthroscopic
level. electrosurgical hook blades or a radiofrequency