Page 72 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

Chapter 5 · Surgery of the ear

skin and underlying cartilage, as with treatment of aural Aural haematomas
haematomas (see below). Pathophysiology
VetBooks.ir cartilage can be closed with simple interrupted Aural haematomas are thought to be secondary to
• Lacerations that extend through the underlying
sutures if the cartilage is not displaced, or can be
trauma. Vigorous head shaking in dogs with external ear
pulled together with vertical mattress sutures, with
the deeper bites of each stitch apposing the canal irritation causes separation of the skin of the inner
pinna from the cartilage, or separation between the carti-
cartilage layer. lage layers or between the perichondrium and cartilage.
• Full-thickness lacerations require closure of both skin The tiny vessels that perforate the cartilage rupture
surfaces, using either a simple interrupted pattern on and bleed until pressure builds up sufficiently to stop
each side of the pinna or a simple interrupted pattern the haemorrhage. If the dog continues to shake its head,
on one side and a vertical mattress pattern to realign further separation of the pinna layers allows continued or
the cartilage and skin on the other side. progressive accumulation of blood and clots.
Not all dogs and cats with aural haematomas have
Marginal defects otitis externa (OE), and 15–45% of affected animals may
have no evidence of external ear canal disease. Because
Defects of the pinna margins can be corrected by amputa- head shaking is thought to be the underlying traumatic
tion of the affected part. For large defects, a pedicle flap event that leads to haemorrhage, otoscopic and dermato-
can be used to replace the edge. logical examinations and ear and skin cytology should be
performed on all affected animals to rule out or diagnose
Partial amputation: A curved incision is made with a predisposing conditions.
scalpel, cautery or laser along the margin, to excise as In animals with aural haematomas, the pinna is often
little tissue as possible. The medial and lateral skin edges infiltrated with eosinophils and mast cells. This suggests
are pulled together with 1.5 metric (4/0 USP) non-absorb- that many of the affected animals have underlying hyper-
able suture material in a continuous pattern. The ear is sensitivity. Fluid within the haematoma usually contains a
bandaged against the head or neck to prevent further low percentage of red blood cells, a few inflammatory cells
trauma until the sutures can be removed. and a moderate amount of protein. Fibrin, blood clots and
other debris may also be present. Cartilage around the
Pedicle flap procedure: The pinna is brought to the side haematoma degenerates, and fibrovascular granulation
of the neck or face to determine which site will provide the tissue fills the defects, thickening the pinna and encourag-
most acceptable cosmetic appearance, based on hair ing distortion of its shape during healing.
length, the colour and direction of hair growth, and the
least tension. Conservative treatment
After aseptic preparation of the pinna, a small portion
Conservative treatment involves drainage and flushing
of the defect margin is removed to freshen and straighten
the edges. If the pinna is thin, the defect can be left un- of the haematoma, either through a small incision or with a
large needle, and administration of corticosteroids systemi-
sutured, covered with antibiotic ointment, and bandaged
for 7 days to allow the skin of the pinna to thicken and cally or into the haematoma cavity. This may work best
for small, acute haematomas. Two different protocols for
become more vascular. Bandages are changed as needed
steroid instillation have been used. It is important to keep in
to allow inspection of the margin. mind that recurrence of aural haematomas following drain-
Once the pinna is ready for closure, the pinna and
age, with or without local infusion of cortico steroids, is
donor site are aseptically prepared, and the margins of the common, and surgical intervention may be necessary for
pinna are debrided sparingly. The pinna is placed next to successful management of recurrent cases (Hall et al., 2016).
the donor site, and the outline of the defect is incised at
After aseptic preparation of the pinna, the haematoma
the site. The outer skin of the defect is sutured to the cavity can be aspirated with a 16 G needle and then
elevated flap, and the pinna and site are gently bandaged.
flushed with physiological saline and reaspirated gently
After 2 weeks, the flap is excised to free the pinna.
multiple times until the fluid becomes clear. The cavity is
then injected once daily with dexamethasone (0.25 mg/kg
Medial defects diluted in sterile saline to 0.5–1 ml), or weekly with methyl-
prednisolone acetate (0.5–1 ml) until the haematoma
The medial portion of the pinna can be treated in several
resolves. Injections must be performed using sterile
ways:
technique to prevent infection. Bandaging of the ear is
not necessary except to seal the drain hole or to prevent
• Small defects can be allowed to heal by second
vigorous shaking (Kuwahara, 1986). Similar results are seen
intention
• For larger defects that cover the medial and lateral when steroids are administered systemically to animals
after needle or incisional drainage of the ear. Haematomas
surfaces, a pedicle flap (described above) can be used. treated with daily intralesional or systemic injections of
Once the flap has healed to the lateral margin, it is
dexamethasone usually heal within 3–6 days. Animals that
transected from its base such that the excess can be receive intralesional methylprednisolone acetate may
folded over and sutured to the pinna medially to cover require a second or third injection, but most cases resolve
any raw surfaces. This technique may cause
with a single treatment (Kuwahara, 1986).
obstruction of the blood vessels in the flap at the
folded edge, leading to necrosis
• Alternatively, the original pedicle flap can be severed at Surgical drainage
2 weeks and a second pedicle flap from the top of the A variety of techniques have been proposed.
head applied to its raw medial surface. The ear is The haematoma can be drained and flushed through
bandaged in place for an additional 10–14 days until a long, S-shaped incision on the concave surface of the
the second flap is cut down. pinna. The pinna layers are then apposed with full-thickness
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