Page 126 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Musculoskeletal system: 1.3 The foot 101

VetBooks.ir evidence of trauma to an unossified ungual carti- degree of lameness. Chronic fibrosis of the heel and
deformity of the hoof wall may occur.
lage, with displacement of the cartilage from its
attachment to the ipsilateral palmar process of the
distal phalanx. Differential diagnosis
Abscesses that drain at the coronary band (gravel);
Management subcutaneous abscess; puncture wound.
Since most ossified ungual cartilages are asymptom-
atic, no treatment is required. In horses in which an Diagnosis
ungual cartilage can be definitively identified as the Diagnosis is based on a variable history of trauma
cause of acute lameness, NSAIDs and a long period proximal to the coronary band, lameness, the uni-
of rest are indicated. When a fracture is identified, lateral location of a swelling, heat and pain on palpa-
a bar shoe with several clips or a rim shoe can be tion, and one or more draining tracts (Fig. 1.175).
applied to immobilise the hoof capsule. When the If necessary, inserting a probe into a sinus that
lameness is chronic and refractory to treatment, the reaches the ungual cartilage should differenti-
horse may be worked with judicious use of NSAIDs. ate quittor from a gravel or subcutaneous abscess.
Evaluation of the balance of the horse’s feet may Dorsopalmar and lateromedial radiographs with a
indicate that corrective trimming is required for probe in situ will confirm the origin of the sinus
horses with acute or chronic lameness. A uniaxial in the ungual cartilage or in the palmar process of
neurectomy may be performed in horses with per- the distal phalanx. MRI has been used in compli-
sistent lameness. cated cases of quittor to determine the structures
involved and help guide the management and surgi-
Prognosis cal approach.
The prognosis is good except in the rare circum-
stances where the lameness is sufficiently persistent Management
for the horse to require surgery, in which case it is Necrosis of the ungual cartilage has been treated
guarded. either conservatively with long-term antibiot-
ics or surgically by excision of the infected tis-
QUITTOR sue. Although treatment with broad-spectrum
antibiotics for several weeks may lead to a cure,
Definition/overview recurrence of the drainage is common. For this
Quittor is defined as septic necrosis of the ungual reason, in most horses the traditional approach
cartilage. is to resect the necrotic cartilage. The surgery is
complicated because the ungual cartilage is approx-
Aetiology/pathophysiology imately half inside the hoof capsule and half proxi-
Quittor usually occurs following direct trauma to mal to the coronary band. Although an elliptical
the ungual cartilage or from ascending infection incision over the proximal margin of the ungual
from within the foot. The infection is particularly cartilage provides access to the necrotic tissue,
persistent because the ungual cartilage has a poor there is no ventral drainage and treatment through
blood supply. The infection causes a marked uni- this proximal approach alone is likely to result in
lateral inflammatory response, with swelling and recurrence. Consequently, combining the proximal
draining sinuses from the integument proximal to approach with a distal approach, 1–2 cm distal to
the coronary band. the coronary band, by trephination through the
hoof capsule provides ventral drainage (Fig. 1.176).
Clinical presentation The proximal incision may be closed by primary
Quittor is a chronic condition that presents with a intention, while the hoof wall defect heals by sec-
unilateral swelling proximal to the coronary band, ondary intention (Figs. 1.177, 1.178). Care must
one or more discharging sinuses and a varying be taken to avoid damaging the palmar reflection of