Vet Cetera magazine 2015

PHOTO / CENTER FOR VETERINARY HEALTH SCIENCES
“We looked at 50 cats for a total of 100 ears,”
Njaa says. “A total of 48 ears, nearly 50 percent,
showed lesions of previous or ongoing otitis
media. This is a much higher occurrence than
the 2009 study reported.”
Otitis media can cause discomfort and irritation
that could result in behavioral issues.
“Middle ear inflammation can lead to facial
neuritis, which could lead to abnormal posture
of the ear pinna. The common misconception
is middle ear inflammation leads to head tilt
but that is a reflection of internal ear inflammation,
not middle ear,” says Njaa. “If both ears
are affected, it can lead to a very subtle sign of
the cat extending its neck.”
Because the changes in the cat’s behavior
are subtle, owners might not pick up on them.
“We did discover that unlike dogs where otitis
media is secondary to otitis externa, in cats
there is not a single case of otitis externa,” he
says. “In the cat, otitis media is thought to occur
primarily as a sequela of upper respiratory
tract disease. This often occurs as a direct consequence
of bacteria from the nasopharynx or
simply auditory (Eustachian) tube dysfunction.
“When talking about the ear, I am referring
to the middle and inner ear compartments.
Because of the bony shell, complex anatomy
and delicate sensory apparatus, few articles
address the pathology of this compartment
in common veterinary journals. When dogs
and cats were used as animal models of otic
pathology in toxicity studies or methods that
mimicked diseases in humans (sound-induced
hearing loss), these studies were buried in specialized
journals not commonly referenced by
veterinarians.”
Njaa’s findings are being included in several
book chapters including Jubb, Kennedy and
Palmer’s Pathology Domestic Animals, G. Maxie
ed, sixth edition 2015; Zachary and McGavin’s
Pathologic Basis of Veterinary Disease, fifth edition
2012, and a sixth edition 2016; and Tumors in
Domestic Animals, D. Meuten, fifth edition 2016.
“There needs to be greater attention paid to
cats with the possibility of otitis media being
more prevalent than once assumed,” Njaa says.
“A problem for practitioners is the lack of clinical
disease or very subtle signs associated with
bilateral otitis media. Most people associate a
head tilt with otitis media, but that actually
is a sign that refers to otitis interna affecting
the cranial nerve VIII or the vestibulocochlear
nerve. Furthermore, otitis media may cause
drooping ears related to facial nerve paralysis
(cranial nerve VII). The droopy ears may be
due to chronic, bilateral otitis media necessitating
imaging studies and appropriate therapy
before it becomes more serious and leads
to otitis interna or meningitis.”
According to Njaa, studies have investigated
upper respiratory disease (rhinitis) in cats leading
to meningitis by traversing the nasal cavity.
These studies did not investigate middle
ears for disease.
“I presume that at least some of the cats with
chronic rhinitis may have had dysfunctional
auditory tubes (Eustachian tubes) that could
have initially led to otitis media followed by
otitis interna and meningitis. This is an area
that has not been pursued and one that I would
love to investigate.”
To read Dr. Njaa’s research in full,
visit okla.st/1Poq180.
2015 Oklahoma State University 9