Page 1182 - Problem-Based Feline Medicine

1174 PART 15 CAT WITH EYE PROBLEMS

for FIP. Serology is confused by intestinal coron- Concurrent anti-inflammatory therapy for anterior
avirus infections. Cats with FIP often have uveitis, e.g. topical 0.5% prednisolone acetate drops
increased total protein and IgG concentrations in applied q 6–12 h are used to suppress the inflamma-
response to viral antigen, and also from cell damage tion associated with the infection, and prevent sec-
resulting from the intense tissue inflammation. It is ondary complications such as glaucoma.
not pathognomonic for FIP, and reflects the
chronic inflammatory nature of the disease.
● FIV uveitis can cause a mild anterior uveitis, and
CRYPTOCOCCUS NEOFORMANS*
anterior chamber flare. The condition can be diag-
nosed with serology using an ELISA test.
Classical signs
● FeLV uveitis can cause signs similar to acute T.
gondii infection, with an inflamed swollen iris and ● Sudden blindness with retinal detachment.
hypopyon. The retina may be infiltrated with tumor Vitreous flare may be present making the
cells, and the retina may occasionally be detached retina difficult to examine.
from neoplasia infiltrating the choroid. ● Anterior uveitis (anterior chamber flare,
miosis, inflamed discolored iris).
Other inflammatory conditions that present with
● Exophthalmos (eye bulging forward).
chorioretinitis include:
● +/- mucopurulent discharge with sneezing
● Fungal diseases especially cryptococcosis, blasto-
and a swollen nose.
mycosis, histoplasmosis, candidiasis and coccid-
● Neurological signs.
ioidomycosis. These diseases present with signs of
● Chronic skin granulomas.
uveitis and multifocal granulomatous chorioretinitis
that appears as small brownish nodules in the retina,
See the main references on page 25 (The Cat With Signs
and may cause blindness. Systemic signs of fever,
of Chronic Nasal Disease).
inappetence, weight loss and dyspnea are often
present. Serological tests are available to differenti-
ate these infections.
Pathogenesis
Treatment
Cryptococcosis is the most common fungal infection
A combination of drugs that inhibit the production affecting cats which occurs throughout the world.
of folinic acid necessary for T. gondii proliferation
Cryptococcus neoformans is a budding, capsulated
has been the mainstay of treatment in people. The most
yeast-like fungus found in soil or in avian excreta.
common combination is pyrimethamine, a dihydro-
In Australia, there is an association of the organism
folate reductase inhibitor, and a sulfonamide, which
C. neoformans var. gatti with the bark of a Eucalypt
inhibits production of folic acid. Unfortunately, cats do
tree, the River Red Gum (River and Forest varieties),
not tolerate sulfa drugs as well as people, and often
which has been exported world wide as a timber
develop gastrointestinal side effects.
tree.
Trimethoprim/sulfadiazine (30 mg/kg PO q 12 h) may
In general, all deep fungal infections enter the body by
be given alone, or with pyrimethamine (0.5 mg/kg PO q
the inhalation of aerosolized spores leading to either
24 h). Supplement with folinic acid (1 mg/kg PO q 24 h).
fungal rhinitis (e.g. Cryptococcus) or pneumonia (e.g.
Other antimicrobial drugs that are used to control blastomycosis, histoplasmosis), with subsequent dis-
T. gondii infection include tetracyclines, clindamycin, semination to other parts of the body, including the eye,
clarithromycin and atovoquone. by hematogenous or lymphatic spread.
Clindamycin (Antirobe, Upjohn) at a dose rate of 12.5 The initial ocular site for establishment of infection is
mg/kg q 12 h for 3–4 weeks is the most common treat- usually the choroid, and the anterior uveal tract is
ment used in cats. often involved later in the course of the infection.