Page 385 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

360 CHAPTER 1

VetBooks.ir recognised. DDFT tears will be addressed separately cause the DDFT to move independently in relation
Tendon disease within the sheath is increasingly
to the SDFT.
Other lesions include erosions of the proximal
but spontaneous partial rupture or tears may occur
in the SDFT, DDFT, or both. SDFT lesions are less scutum and bone production at the insertions of
common than in the DDFT and may extend into one the annular ligaments on the sesamoid bones and
or both insertion branches. These lesions appear as phalanges. There may also be thickening of the
hypoechogenic areas, forming either a cleft, a wedge- peripheral tissues, including annular ligaments and
shaped area or more diffuse lesions, extending into subcutaneous tissue.
the centre or a more peripheral portion of the tendon Partial tears of the manica flexoria may be seen as
(Figs. 1.713, 1.714). They can always be followed for a focal, hypoechogenic thickening near the attach-
some distance proximodistally. Occasionally, these ment of the manica, often forming an amorphous
lesions will cause the affected tendon to split into two mass (Fig. 1.716). In complete tears the redundant
or more independent portions. Complete rupture may manica may be seen to float in one of the proximal
also occur, the cut ends moving apart several centime- recesses of the sheath or, most often, to curl up into
tres proximally and distally. a soft-tissue mass lateral to the SDFT. This may be
Echogenic fibrous adhesions may be clearly iden- difficult to differentiate from hypertrophic synovial
tified between tendons or between the tendon(s) and masses.
the parietal sheath (Fig. 1.715), although the syno-
vial thickening and tight space caused by the inex- Magnetic resonance imaging
tensible annular ligaments often obscure them. They MRI has recently been used to assess soft-tissue
may, however, be suspected, or confirmed by evalu- structures in the digital sheath. MRI is particularly
ating the relative motion of each tendon in relation sensitive to detect lesions within the flexor tendons
to the other and to the sheath wall while flexing and and sesamoidean ligaments and to look for adhe-
extending specifically the fetlock and the DIP joint. sions. It is notably useful when lesions are suspected
Fetlock flexion alone should cause the two flexor ten- in the distal fetlock and proximal pastern region,
dons to move together in relation to the sheath wall where the ergot and the sharp angle make ultrasono-
(annular ligament and scutum), DIP flexion should graphic assessment difficult in most horses.

1.713 1.714

Figs. 1.713, 1.714 (1.713) Transverse sonogram of the palmaromedial aspect of the DFTS just at the level
of the PSB showing an obvious hypoechoic cleft in the medial edge of the SDFT plus subcutaneous fibrous
thickening, mild thickening of the AL and a possible adhesion from the palmar aspect of the tendon to the
sheath wall. (1.714) Surgical dissection at an open tenosynoviotomy, which clearly confirms the full-thickness
split in the medial SDFT. (Photos courtesy Graham Munroe)