Page 319 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

294 CHAPTER 1

VetBooks.ir forming a stiff, individual unit with maximal stresses return to exercise, particularly if the tendon lesion
is underestimated or overlooked, may cause more
occurring at the transition to normal parenchyma.
Clinical presentation severe damage with significant worsening of the
prognosis.
The injury is often associated with a sudden-onset
lameness, which occurs during or immediately after Differential diagnosis
exercise. The lameness is variable, however, with up Subcutaneous or paratendonous trauma (para-
to 40% horses not showing overt lameness. If pres- tendonitis) secondary to bandage rub, dermatitis,
ent, it is most severe a few hours after injury or on direct trauma; swelling/oedema from inflamma-
the following day. Heat and swelling over the palmar tion or infection elsewhere in the limb (e.g. foot
aspect of the metacarpus (less commonly the plan- sepsis, mud fever, etc.); tenosynovitis of the digital
tar metatarsus) develop over the first 24 hours, due sheath; inferior check ligament desmitis; SL des-
to oedema and hyperaemia. Pain is usually marked mitis; lymphangitis.
on palpation, but this gradually recedes over 4–10
days, leaving a firm, bow-shaped swelling over the Diagnosis
‘ tendon’ area (‘bowed tendon’) (Fig. 1.555). There Clinical examination
may be associated distension of the carpal and/or A diagnosis may be suspected on the basis of swell-
digital sheath(s). Oedema may extend over the pas- ing, heat and pain over the palmar metacarpal or
tern and/or carpal region. plantar metatarsal area. These signs are not pathog-
The lameness usually recedes within 2 to 10 days. nomonic and there is little correlation between clini-
The severity of the signs does not correlate well cal presentation, palpation and severity of the lesions
with the severity of the tear and some horses with as based on ultrasonographic appearance. Lameness
very large tears may not be lame at all. A premature is not a good indicator. Pain may be elicited on pal-
pation, but this is not specific as normal horses may
flinch to palpation, whereas other horses with ten-
1.555 don strain may not elicit a painful reaction.

Ultrasonography
This is the diagnostic method of choice. If car-
ried out before 7–10 days, it may help to confirm
the presence of injury. However, the examination
should be repeated after 10–15 days, as the lesions
may increase in size over the course of several days.
Furthermore, the initial haemorrhage may be of a
similar echogenicity to normal parenchyma, mak-
ing evaluation of the lesion’s severity more dif-
ficult. High-definition ultrasound systems using
Fig. 1.555 7.5–15 MHz linear array transducers are preferred,
Typical swelling although higher frequencies can be of use to assess
(‘bowed tendon’) superficial trauma or paratendonitis. A systematic
over the mid- approach must be used and comparison with the
metacarpal opposite limb can be valuable.
region of a The palmar aspect of the distal limb is clipped
horse suffering from the accessory carpal bone/point of the cal-
from subacute caneus to the ergot (or to the bulbs of the heels if
tendonitis of the the pastern is to be evaluated) and laterally as far
SDFT. as the splint bones or phalanges. There are several