Page 77 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery

Preoperative assessment: Patient evaluation and prep- modalities will be required, after surgical cytoreduction
aration should be performed as for a lateral ear canal and histopathological confirmation of tumour type, to
VetBooks.ir obstructed by hyperplastic tissue, it may be difficult to pected of having neoplasia should have thoracic radio-
resection. Because the horizontal ear canal is often
control the growth and spread of neoplasia. Patients sus-
graphy or CT to determine whether gross metastatic
assess whether a vertical resection will be sufficient or
whether TECA is needed.
disease is present. Metastasis of ceruminous gland
adenocarcinomas may occur in half of affected cats.
Surgical technique: Details of this procedure are given in
Operative Technique 5.2. Preoperative and perioperative medication: TECA with
lateral bulla osteotomy is a very painful procedure, and
Postoperative complications: The most common compli- pre-emptive analgesic administration should be used to
cations include dehiscence and stenosis. Primary repair of ease the animal’s recovery. The day before surgery, a
dehiscence is essential to prevent secondary stenosis fentanyl patch can be placed and non-steroidal anti-
and subsequent OM and fistulation. Facial nerve palsy and inflammatory drugs (NSAIDs) administered (if the patient
infection are uncommon, and most owners are satisfied has not been treated recently with steroids). Alternatively,
with the cosmetic results. pre-anaesthetic medication should include an opioid and
an NSAID administered perioperatively. These drugs
Prognosis: Excellent results have been reported in should be continued for several days after surgery once
72–95% of dogs and cats. In one series, 95% of animals the animal has recovered enough to take oral medica-
with end-stage OE were reported to be improved by the tions. Another option in dogs is placement of a wound
procedure, even when the horizontal canal, whilst still soaker catheter to allow continuous delivery of lidocaine
patent, was hyperplastic (McCarthy and Caywood, 1992). to the site for 38 hours after surgery. When compared
Operated patients still require continued therapy for otitis with intravenous morphine, continuous local lidocaine
or its underlying causes, but they may require less fre- infusion provided equipotent analgesia and produced
quent treatments. Animals that develop occlusion of the less sedation in dogs undergoing TECA and bulla oste-
horizontal ear canal will need TECA and bulla osteotomy otomy (Wolfe et al., 2006).
to resolve clinical signs. Because thorough preparation of the ear canal is diffi-
cult, this procedure is classified as ‘dirty’, justifying the
Total ear canal ablation with lateral bulla use of perioperative antibiotics. Ideally, the choice of anti-
biotics is based on results of prior cytology and culture
osteotomy and sensitivity testing. Intraoperative cultures of the bulla
TECA with lateral bulla osteotomy is an extremely chal- should be taken to confirm the bacterial species and anti-
lenging procedure; supervised training and practice microbial susceptibility. Timing of intraoperative cultures is
should be obtained by the veterinary surgeon before offer- controversial, because isolates obtained before and after
ing this procedure to clients. Many practitioners will refer flushing differ in 70% of operated ears; if the primary
patients with end-stage otitis because of the difficulty of concern is residual bacteria, then culture after flushing
this surgery and high potential for complications. Referral would make the most sense.
may also be necessary to evaluate the animal for primary
causes of otic inflammation, particularly uncontrolled or Surgical technique: Details of this procedure are given in
poorly controlled allergic dermatitis. Whilst removal of the Operative Technique 5.3.
ear canals provides relief to many animals, underlying skin
conditions can still cause pruritus and proliferation of Postoperative complications: Complications are seen in
the remainder of the pinna; if these are not controlled, the 29–68% of animals that undergo TECA with bulla osteot-
owners will be dissatisfied with the results of surgery. omy and are reported in 82% of animals if bulla osteotomy
TECA should be combined with bulla osteotomy to prevent is not performed, probably because of incomplete removal
recurrent fistulation and infection. of affected epithelium within the osseous canal and bulla.
Facial nerve paralysis occurs in 25–50% of dogs after
Preoperative assessment: Patients with end-stage otitis the procedure and is permanent in 10–15% of all dogs.
should have already undergone systemic and dermato- Temporary facial nerve palsy usually resolves in 1–4
logical evaluations, as well as culture and cytology of the weeks; administration of eye lubricants three times per day
ear canals. Neurological function should be examined is recommended until eyelid function improves. Dogs with
preoperatively. If the dog has a diminished blink reflex or permanent facial nerve paralysis should undergo Schirmer
drooping lip, then the facial nerve may be embedded in tear tests to determine whether artificial tears are neces-
hyperplastic tissue or damaged by extensive inflammation, sary to prevent keratoconjunctivitis sicca. Postoperative
conditions that can make the surgery more challenging. cellulitus and infection are also common complications,
Animals with head tilt and nystagmus may also be slightly particularly if infected bulla lining or epithelial remnants
worse after surgery. lining the external acoustic meatus or cartilaginous attach-
Because TECA is almost always combined with bulla ments are not removed. Draining fistulas will appear 1–12
osteotomy, many veterinary surgeons forgo radiographic months after the surgery in 5–10% of animals; residual
imaging of the skull in animals with obvious end-stage tissue must be removed through a lateral approach or a
otitis. In brachycephalic breeds, however, CT is very useful ventral bulla osteotomy.
for determining the location of the osseous bullae, Other complications include dehiscence, neurological
because they may be difficult to reach from a lateral abnormalities from inner ear damage (nystagmus, circling,
approach in some dogs. If unilateral OE is present or neo- head tilt, ataxia), hypoglossal nerve damage, Horner’s syn -
plasia is suspected, skull radiography or CT is recom- drome (particularly in cats) and avascular necrosis of
mended to determine the extent of the disease. If a tumour the pinna. In patients with allergic dermatitis, persistent
has invaded the tympanic bulla, owners should be warned changes to the skin of the concave pinnae (e.g. erythema,
that surgical cure is unlikely and that other treatment pruritus, lichenification, glandular hyperplasia) may continue

68

Ch05 HNT.indd 68 31/08/2018 10:56