Page 349 - Problem-Based Feline Medicine

18 – THE THIN, INAPPETENT CAT 341

(pars planitis), focal retinal chorioretinitis and reti- – Small numbers of cats (up to 10–20%) have
nal hemorrhages have been reported. delayed seroconversion or may never seroconvert.
● Neoplasia including lymphoma (often extra-nodal), – The cat is in the terminal stages of the disease,
leukemia, and several others have been associated when antibody production declines.
with the terminal stage of the disease. However, the
Detection of FIV infection does not prove that
exact role of FIV in the neoplastic process is
the clinical signs are necessarily related to the
unclear.
infection.
● Central and peripheral nervous system disease
● Since cats can live for years in the “asymptomatic”
has been associated with FIV infections. These
stage of the disease, the clinician should try to
signs may be transient. Clinical signs include
decide if the virus is a cause, contributing factor, or
behavior changes, seizures, paresis and anisocoria.
just incidental to the cat’s problem.
Concomitant infections (cryptococcosis, toxoplas-
mosis or FIP) may contribute to neurologic signs. Immunoflourescent antibody or western blot tech-
● Renal disease and failure may have an association niques may be used to confirm the presence of FIV
with the FIV virus. Since many older cats suffer antibody, particularly in ELISA-positive cats from
from chronic renal failure, the exact association low-risk populations, or if initial test results were
between the virus and renal failure has yet to be equivocal.
determined.
Non-specific findings on routine hematology and bio-
chemistry include:
Diagnosis ● Various cytopenias including neutropenia, throm-
bocytopenia, lymphopenia, and anemia.
Diagnosis of FIV infection is based on serological
● Mild non-regenerative anemia.
evidence of the presence of FIV specific antibodies.
● A polyclonal hyperglobulinemia.
● In practice, diagnostic kits are available to detect
antibody to either p24 core protein or gp41 enve-
lope protein using enzyme-linked immunosor-
bent assay (ELISA) or rapid immunomigration Differential diagnosis
(RIM).
Feline leukemia virus infection (FeLV) may be clini-
Interpretation of a positive antibody result: cally very similar to FIV infection, as many signs are
● Vaccinated cats will test positive with all current associated with the immunosuppression which is common
testing methods. to both conditions.
● In unvaccinated cats, FIV antibodies are associated ● Most cats that are tested for FeLV probably should
with lifelong viral infection. A positive test implies be tested for FIV.
a persistently infected cat.
The dry form of feline infectious peritonitis (FIP)
● Passive transfer of antibody via milk will result in
may lead to signs of wasting, neurologic signs, renal
a positive test in kittens nursed by an infected
failure and ocular disease. The “dry” form of FIP is
queen. Such kittens should not be tested until at
extremely difficult to diagnose without histologic
least 6 months of age.
examination of tissue.
● False-positive results occur with ELISA or RIM
tests, but at a low frequency. A positive test should be Toxoplasmosis causes neurologic and ocular signs as
confirmed using a western blot if it will influence well as wasting. FIV and toxoplasmosis may also occur
management of the cat. concurrently.
Interpretation of a negative antibody result:
● The cat is not infected with FIV.
Treatment
● The cat is infected but no antibodies are present.
– This occurs in early stages of infection, usually The FIV status of the cat should not necessarily pre-
2–4 weeks after infection. clude treatment for other diseases.