Page 850 - Problem-Based Feline Medicine

842 PART 10 CAT WITH SIGNS OF NEUROLOGICAL DISEASE

ture and sensitivity are not available, a broad-spectrum Prevention
antibiotic is chosen such as trimethoprim-sulfa,
Treat otitis externa effectively when it occurs.
cephalosporin or a penicillinase-resistant penicillin
(enrofloxacin). Treat ear mites.
Antibiotic treatment should be continued for 6–8
weeks.
MIDDLE EAR POLYPS**
If otitis externa is present, the antibiotic is chosen
based on the culture and sensitivity of the external ear Classical signs
canal. The otitis externa should be treated as well.
● Mild and slowly progressive head tilt.
Systemic treatment is preferable if the tympanic
● +/- respiratory signs.
membrane is perforated or cannot be visualized.
● +/- signs of otitis externa.
Avoid topical drugs that are toxic for the vestibular
● +/- facial paresis/paralysis, +/- Horner’s
and/or auditory system (gentamycin, neomycin).
syndrome +/- keratoconjunctivitis sicca,
Selamectin (Revolution®) or systemic ivermectin
+/- deafness.
(200–300 μg/kg IM, SC, PO) is preferable as a miticide
rather than topical treatment.
Cats with radiographic changes in the bullae are treated Pathogenesis
with surgical curettage of the tympanic bulla to allow
The pathogenesis is incompletely understood.
drainage, followed by long-term antibiotherapy based
on the culture and sensitivity obtained from the sample The polyp originates from the middle ear cavity and
collected at time of surgery. If the culture is negative, is composed of inflammatory granulation tissue cov-
a broad-spectrum antibiotic as listed above is adminis- ered by respiratory epithelium.
tered for 2–4 weeks.
The instigating cause is not exactly known. Some
If there is chronic or recurrent otitis externa, ablation of believe that it is congenital, to explain its frequency in
the external ear canal is indicated. very young cats. Others postulate that it results from
chronic inflammatory middle ear disease, secondary to
In the presence of paralysis of the eyelids, artificial
upper respiratory infections. The respiratory infection
tears are unnecessary if tear secretion is normal as the
would create abnormalities in the eustachian tube
spread of the tear film is taken over by the third eyelid.
epithelium, resulting in poor middle ear ventilation and
Artificial tears should be administered 2–6 times daily
secondary inflammation.
in the affected eye, if the Schirmer tear test is abnor-
mal (< 10 mm/minute), to avoid development of a Most cats with middle ear polyps have a bacterial
corneal ulcer. infection. The most common bacterial isolates are
Pasteurella multocida, Streptococcus, Staphylococcus,
Bacteroides and Pseudomonas.
Prognosis The polypoid growth has a tendency to exit the mid-
dle ear cavity. It can do so by rupturing the tympanic
Facial paralysis and partial Horner’s syndrome
membrane and emerging into the external ear canal,
often remain, although the severity is much improved.
causing characteristic signs of otitis externa, or it
An ipsilateral mild deviation of the face occurs over
enters the eustachian tube to exit into the nasophar-
time.
ynx with subsequent upper respiratory signs. The fre-
The vestibular signs resolve in most cases, except for quency of each end location versus the other is
the head tilt, which frequently remains for the life of unknown.
the animal.
The polypoid growth within the middle ear cavity may
The cases managed medically may recur and require encroach on the inner ear leading to vestibular
surgical curettage at later date. signs.