Page 91 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

66 CHAPTER 1

VetBooks.ir may lead to resorption of bone from the margins of developing thrush than those with wide and shallow
sulci (Fig. 1.110). The disease is common when the
the distal phalanx, which is radiographically identi-
fied as pedal osteitis.
frog becomes too moist under a full pad.
Management Clinical presentation
The treatment of foot bruising depends on the Horses with thrush usually present because the
cause. Isolated stone bruises usually require nothing affected foot has a characteristic foul odour and
more than rest and NSAIDs to provide analgesia; discharge, and the surface of the frog is ragged.
these are titrated against the severity of discom- Affected animals are often not lame, but deeper
fort experienced by the horse. Iceing the affected damage, especially between the bulbs of the heel,
foot for 24 hours may decrease the inflamma- can be painful (Fig. 1.110).
tion. Partially paring the surface of the horn over
the bruise may relieve pressure from the area as it Differential diagnosis
heals. Recurrent bruising associated with flat soles Canker.
requires protection of the sole, either with seated-
out wide-web shoes or full pads. Bruising in the sole Diagnosis
and lamellae associated with laminitis will recur The characteristic odour and appearance of the
until corrective shoeing has eliminated sole pres- frog are usually sufficient to make a diagnosis of
sure distal to the solar margin of the distal phalanx thrush, but it may need to be distinguished from
and stresses within the dorsal lamellae. Suppurative early canker. The symptoms and progression
bruises should be treated as abscesses and the cause of thrush differ from those of canker in several
removed whenever possible. ways: (1) thrush is a degenerative condition of the
superficial layers of the frog, whereas canker is a
Prognosis proliferative condition affecting the basal layers;
The prognosis with bruising varies with the cause.
When the bruising is an isolated event, a full recov-
ery is probable, but when the bruising is secondary
to conformation or concurrent disease, the progno- 1.110
sis for recovery without recurrence is guarded.

THRUSH

Definition/overview
Thrush is a degenerative keratolytic condition of the
frog and adjacent sulci.

Aetiology/pathophysiology
Thrush is probably caused by an anaerobic bacte-
rial infection, but the specific aetiological agent
has not been identified. The disease is frequently
seen in horses standing in moist unhygienic condi-
tions or subjected to poor daily foot management.
Thrush usually starts superficially on the surface of
the frog, particularly in the central and paracuneal
sulci, before extending deeper into the stratum cor-
neum of the frog and occasionally reaching the ger- Fig. 1.110 A foot with severe thrush infection in the
minal layers of the epidermis and the dermis. Horses central sulci of the frog and midline of the bulbs of the
with deep and/or narrow sulci are more prone to heel. (Photo courtesy Graham Munroe)