Page 1224 - Problem-Based Feline Medicine

1216 PART 15 CAT WITH EYE PROBLEMS

Recently a new chlamydial agent, Neochlamydia hart- positive results occur in the presence of secondary
mannellae, an amebic endosymbiont, has been identi- bacterial infections.
fied in cats. In a study of 226 samples from cats with
Fluorescent antibody tests can also be done on con-
keratitis or conjunctivitis and 30 healthy cats, 12% were
junctival scrapings.
found to have Chlamydophila felis (Chlamydia psittaci)
and 39% N. hartmannellae. Both organisms were found Culture is very difficult and requires specific growth
to be significantly associated with disease. media (usually embryonated eggs), and specialized
laboratories.

Clinical signs Differential diagnosis

Initially, there is unilateral conjunctivitis, with the Herpes conjunctivitis.
signs spreading to involve the other eye several days later. ● The conjunctiva is less inflamed in acute FHV-1
infections.
Acute infections have intense conjunctival hyperemia,
● Chronic cases have a serous ocular discharge with
with chemosis and a serous ocular discharge. This pro-
hardly any sign of conjunctivitis.
gresses to a copious purulent discharge over a few days.
● In the acute form, respiratory signs are more pro-
Chemosis can be so severe that the cornea and intra- nounced, with sneezing, serous discharge progressing
ocular structures are difficult to examine. Signs tend to to mucopurulence, anorexia, pyrexia and depression.
be more severe in kittens than adult cats. ● Young cats are more commonly infected with acute
signs.
Conjunctival lymphoid follicles are often seen in
● Laboratory diagnosis based on PCR, virus isolation
chronic cases of the disease, and older cats. The surface
or fluorescent antibody may be supportive.
of the conjunctiva may have a few, or be covered with
lymphoid follicles, and this is accompanied by a serous Mycoplasma conjunctivitis.
discharge. ● A mild disease with serous discharge.
● Mild respiratory signs, unless co-infected with FHV-1.
Respiratory signs such as sneezing are absent, or very
● A pseudomembrane may develop composed of
minor compared to ocular signs.
a thick white exudate.
Chlamydial keratoconjunctivitis occurs in cats of all ● It responds rapidly to a wide range of antibiotics.
ages. ● Cytology may reveal small basophylic inclusion
bodies, which are coccoid or coccobacillary, and
are seen in the periphery of the cytoplasm of the
epithelial cells.
Diagnosis
● Culture of organism can be done in most labora-
Typically, there is a history of acute conjunctivitis, tories.
which may be accompanied by sneezing and a mild
Neoplasia: squamous cell carcinoma.
nasal discharge. The conjunctivitis can be quite dramatic,
● Typically involves lower lid in depigmented eyelids.
with an intensely red swollen conjunctiva in acute
● Cytology and fine-needle biopsy should confirm
cases. Chronic cases may have an obvious follicular
this diagnosis.
conjunctivitis.
● Lesions are usually red, raised and ulcerated.
Conjunctival cytology may show presence of intra-
Primary bacterial conjunctivitis.
cytoplasmic inclusion bodies. These are seen as pale
● This is not common in cats.
pink granular clusters that may indent the nucleus.
● There will be less inflammation and discharge
There are ELISA and latex agglutination tests avail- compared to Chlamydophila felis and FHV-1 con-
able to support a diagnosis. Discharges should be junctivitis.
cleaned from the eye, and then a dry swab or scraping ● The discharge is more likely to be mucopurulent.
used to obtain conjunctival cells for the tests. False-