Page 1274 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Skin 1249

VetBooks.ir INFECTIOUS CAUSES – BACTERIAL 12.42

ABSCESS

Definition/overview
An abscess is an aggregation of leucocytes and tis-
sue debris related to the skin and subcutis; it may be
infected or sterile.

Aetiology/pathophysiology
Infected abscesses can be caused by a variety of
organisms, but those more commonly involved are
Streptococcus equi (Fig. 12.42), Corynebacterium pseudo-
tuberculosis and Clostridium spp. They are often asso-
ciated with intramuscular injections or wounds, but
can be disseminated through the lymphatic system.
Ectoparasites were incriminated in one outbreak of
C. pseudotuberculosis. Fig. 12.42 Streptococcus equi abscessation caused a
large alopecic area and skin slough in this unvaccinated
Clinical presentation mare during a strangles outbreak. (Reprinted from
Abscesses usually appear as subcutaneous swell- Pascoe RR and Knottenbelt DC (1999) Manual of Equine
ings that may fluctuate. Acute abscesses are Dermatology, WB Saunders, with permission)
attached to the skin and may be hot and pain-
ful. Chronic abscesses may be walled off and may
or may not be attached to the skin. Clostridial CHEEK ABSCESS
abscesses often have gas formation, acute swelling
and severe pain. Definition/overview
This is acute abscess formation at or around the lat-
Differential diagnosis eral commissures of the mouth.
Haematoma; cyst; acute eosinophilic granuloma;
hernia. Aetiology/pathophysiology
Cheek abscesses are caused by penetration of the
Diagnosis buccal mucosa by grass, barley or oat awns, or by lac-
Aspiration of contents followed by culture and cyto- erations of the buccal mucosa by cheek or wolf teeth,
logical examination of a smear is used for diagnosis. followed by infection.

Management Clinical presentation
Surgical drainage is indicated. Antibiotics may Acute painful swelling of the ‘bit’ area or adjacent
be required. Aeration of affected tissues by exten- cheek area (Fig. 12.43), a small area of exudation
sive surgical incision is important for clostridial over a pointing abscess and hair loss (alopecia) may
infections. be observed.

Prognosis Differential diagnosis
The prognosis is very good if full drainage is estab- Bit injury in the mouth; cuts inside the commissure;
lished, but poor if pockets of infection remain. foreign bodies.