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Fact Sheet
Abscesses
in Dogs and Cats
 An
abscess is a localized, encapsulated, accumulation of solid
or liquid material. This material represents tissue breakdown
products. The material inside an abscess (pus) is generally
cloudy and white to off-white to yellowish in color. It
is composed primarily of serum, blood, liquefied tissue
debris and degenerated or toxic neutrophils (a type of
white blood cell) with lesser numbers of other types of
white blood cells such as macrophages and lymphocytes.
Abscesses occur when microorganisms,
or foreign objects, or both, gain entrance into body tissues.
The resultant tissue reaction causes an accumulation of
purulent exudates in the tissue, with components as described
above. At this early point, the affected area is best described
as a cellulitis. If the cellulitis is not quickly resolved,
or if the accumulating debris is not promptly discharged
to an external body surface, then the body will attempt
to wall off the affected area by forming a capsule of fibrin
around it. Fibrin is gluey, web-like type of protein that
also serves as a main component of scabs. Once the fibrin
capsule is complete, the cellulitis is said to have become
an abscess.
Progressive increases in the
pressure within the abscess cavity can lead in time to
rupture of the abscess. However, prolonged delay in evacuation
of the contents of the abscess cavity can result in a thicker,
tougher, more rigid abscess wall composed of fibrous connective
tissue. In this case, healing will eventually require the
filling of the cavity by scar tissue. Unfortunately, this
does not always result in total elimination of the inciting
elements of the abscess; chronic or intermittent discharge
of exudates from a draining sinus tract is a potential
squela.
Among dogs and cats, abscesses
can occur almost anywhere, but they are most common on
the skin, within the anal glands, prostate gland, or mammary
glands, and behind the eyeball.
Signs and Symptoms
Clinical signs of an abscess
will vary depending on the location of the abscess and
the organ system(s) affected. In general, however, all
abscesses cause some degree of pain, swelling, redness,
heat, and loss of function.
A painful, angry, open wound
with material draining out may be visible if the abscess
is superficial and has ruptured to an external body surface.
Sometimes fever, loss of appetite, and/or painfulness in
a particular area are the only signs.
Often there is some prior
history of trauma, fighting, or infection in the affected
area. Tissue destruction may be minor or substantial. Even
body organs not directly involved in the abscess can be
hampered and compromised due to pressure from an adjacent
abscess mass.
Diagnosis
Abscesses are usually diagnosed
presumptively by physical examination and observation.
Often microscopic examination of the abscess contents is
necessary in order to confirm that the structure is an
abscess and not a similarly appearing tumor, cyst, or granuloma.
Blood testing will usually
show abnormalities in the white blood cell counts.
Treatment
Treatment of abscesses centers
around identifying and removing the original cause(s),
beginning antibiotic therapy, and establishing adequate
drainage, if possible. Large abscess and those associated
with large amounts of dead tissue may require surgery.
The prognosis for abscesses
is generally good, but some abscesses may become complicated
by sepsis (blood-borne infection), or chronic, draining
tracts. Furthermore, abscesses which rupture internally
may lead to peritonitis or pleuritis. In these cases, the
prognosis is worse.
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