#Part1Prognosis for FIV-infected cats
ABCD recommends that cats should never be euthanased just because
of an FIV positive test result. There have been reports that
FIV-infected cats may live as long as uninfected cats (Kohmoto et al.
1998; Addie et al. 2000; Levy et al. 2007). However, FIV-positive cats
have a higher chance of developing clinical signs, mainly due to
secondary infection, immune-mediated disease or neoplasia [Lutz et al.
1990; Hosie et al. 1989; Lutz et al. 1988b].
The duration of
asymptomatic stage varies according to the infecting variant [Pedersen
et al. 2001]. Based on experimental studies, cats infected at a younger
age are more likely to progress to an immunodeficiency state [George et
al. 1993; Podell at al. 1997].
One of the most important preventative health measures is to
protect the cat from other infections. In FIV infected cats secondary
infections may not only cause clinical signs but may also lead to
progression of the FIV infection itself. Confining the cat indoors will
help to avoid the risk of acquiring other infections through contact
with neighbouring cats – as well as avoiding potential transmission of
FIV. In some multi-cat households in which other infectious disease
problems are endemic, consideration should be given to isolating FIV
Asymptomatic FIV infected cats should be neutered. This will help
to reduce aggression in male cats and the risk of transmission of
infection. It will also help to reduce wandering and contact with
Frequent health checks
FIV-infected cats should receive veterinary health checks at least
every six months which should include monitoring of their weight.
Periodic routine laboratory testing (haematology, biochemistry,
urinalysis) should be considered. CD4 and CD8 monitoring to stage FIV
infected cats is controversial and is neither generally available nor
realistic in most practice situations.
Surgery is generally well
tolerated by asymptomatic FIV-infected cats, but perioperative
antibiotic administration should be used in all surgeries and dental
procedures. FIVinfected cats can be housed in the same ward as other
hospitalized patients; they should, however, be housed in individual
cages. It should be considered that they may be ABCD Guidelines on
Feline Immunodeficiency Virus 11/21 immune-deficient and should be kept
away from cats with other infectious diseases. Under no circumstances
should they be placed in a "contagious ward" with cats suffering from
infections such as viral respiratory disease.
Vaccination of FIV-infected cats
Whether or not FIV-infected cats should receive routine vaccination
is a controversial subject. Experimental studies have shown that
asymptomatic infected FIV-cats in early stages of infection develop a
strong immune response following vaccination indicating that efficacy of
vaccines is as good as would be expected in non infected cats. However,
it is not known if cats who have progressed to later stages of
infection with immunodeficiency develop an adequate response to
On the other hand, safety concerns have been raised
about vaccination in FIV-infected cats. First, immune stimulation
related to the vaccine may lead to progression of FIV infection by
altering the balance between immune system and virus. Stimulation of
FIVinfected lymphocytes is also known to promote virus production in
vitro. In vivo, vaccination of chronically infected FIV-infected cats
with a synthetic peptide was associated with a decrease in the CD4/CD8
ratio. The potential benefits and risks of vaccinating FIV-infected cats
should be weighed up in individual cats. In elderly indoor cats which
have been vaccinated previously, the risk of acquiring infection is very
low so booster vaccination is (probably) best avoided. In outdoor cats
with risk of exposure to other infections vaccination is strongly
Although there is no scientific evidence that FIV-infected
cats are at increased risk from modified life virus vaccines,
inactivated vaccines are recommended whenever available as in
immune-suppressed cats these vaccines may retain some pathogenic
potential and cause clinical disease.
Appropriate supportive treatment of FIV-infected cats relevant to presenting clinical signs should be instituted as early as possible. If
FIV-infected cats are sick, prompt and accurate identification of the
secondary illness is essential to allow early therapeutic intervention
and a successful outcome of treatment. Therefore, more intensive
diagnostic testing should proceed earlier in the course of illness than
might be recommended for uninfected cats. Many cats with FIV infection
respond as well as uninfected cats to appropriate medications although a
longer or more aggressive course of therapy (e.g., antibiotics) may be
Some clinicians report clinical benefits using
corticosteroids and other immune suppressive drugs in FIV-infected cats
with chronic stomatitis, but their use is controversial because of
potential side effects. Griseofulvin has been shown to cause ABCD
Guidelines on Feline Immunodeficiency Virus 12/21 bone marrow
suppression in FIV-infected cats and should not be used [Shelton et al.
1990]. Filgastrim, granulocyte colony-stimulation factor, G-CSF, a
cytokine that is on the market as recombinant human product (rHuG-CSF),
have been used in FIV-infected cats with profound neutropenia but can
increase neutrophil counts in cats with FIV infection [Phillips et al.
2005], but can also lead to a significant increase in virus load in
peripheral blood mononuclear cells during treatment by enhancing
infection of lymphocytes or increased expression of FIV by infected
lymphocytes [Aral et al. 2000].
Erythropoietin, EPO, is on the market
as recombinant human product (rHuEPO) and is effectively used in cats
with non-regenerative anaemia due to endogenous erythropoietin
deficiency in chronic renal failure. FIV-infected cats treated with
human erythropoietin (100 IU/kg SQ q48h) showed a gradual increase in
red and white blood cell counts [Aral et al. 2000]. No increase in virus
loads was observed, and thus, human erythropoietin can be used safely
in FIV-infected cats.
Insulin-like growth factor-1, IGF-1, is on the
market as recombinant human product (rHuIGF-1) and, besides other
actions, has the ability to induce thymic growth and to stimulate T-cell
function. Treatment with human insulin-like growth factor-1 resulted in
a significant increase in thymus size and thymic cortical regeneration
replenishing the peripheral T cell pool in experimentally FIV-infected
cats [Woo et al. 1999]. It could be considered in young FIV-infected
cats as supportive treatment, but there are no field studies so far to
show its effect in naturally FIV-infected cats.
Most antiviral drugs used in cats are licensed for humans and are
specifically intended for treatment of HIV infection. Some of those can
be used to treat FIV infection. However, many of the available drugs are
toxic to cats or ineffective.
is a nucleoside analogue (thymidine derivative) that blocks the reverse
transcriptase of retroviruses. It has been shown that AZT inhibits FIV
virus replication in vitro and in vivo; it can reduce plasma virus load,
improve the immunological and clinical status of FIV-infected cats, and
increases quality of life. In a placebo-controlled trial, AZT improved
stomatitis in naturally infected cats [Hartmann et al. 1995]. Dosage is
5-10 mg/kg q12h PO or SQ. The higher dose should be used carefully as
side effects can develop. For SQ injection, the lyophilized product
should be diluted in isotonic NaCl solution to prevent local irritation.
For PO application, syrup or gelatine capsules (dosage/weight
individually for every cat) can be given. During treatment, a CBC should
be performed regularly (weekly for the first month) because
non-regenerative anaemia is a common side effect especially if the
higher dosage is ABCD Guidelines on Feline Immunodeficiency Virus 13/21
used. If values are stable after the first month, a monthly check is
sufficient. Cats with bone marrow suppression should not be treated.
Studies in which FIV-infected cats were treated for two years showed
that AZT is well tolerated. Some cats may develop a mild decrease of
haematocrit initially in the first three weeks that resolves even if
treatment is continued. If haematocrit drops below 20 %, discontinuation
is recommended and anaemia usually resolves within a few days.
Unfortunately, as in HIV, AZT-resistant mutants of FIV can arise as
early as six months after initiation of treatment.
octahydrochloride, JM3100, SID791, belongs to the new class of bicyclams
that act as selective antagonists of the chemokine receptor CXCR4.
CXCR4 is the main co-receptor for T-cell-line-adapted HIV strains, and
blocking the CXCR4 receptor leads to inhibition of virus entry. FIV also
uses CXCR4 for virus entry [Frey et al. 2001, Willet et al. 1997,
Richardson et al. 1999, Egberink et al. 1999], and a high degree of
homology exists between the human and feline CXCR4. AMD3100 is not
licensed as antiviral compound but as a stem cell activator for patients
that undergo bone marrow transplantation. It is effective against FIV
in vitro, and in a placebo-controlled double-blind study in which 40
naturally FIV-infected cats were treated with AMD 3100 (0.5 mg/kg q12h
SQ for 6 weeks), it caused a statistically significant improvement in
clinical signs and decreased the proviral load in FIV-infected cats.
Cats receiving AMD3100 did not show side effects [Hartmann et al. 2002].
Feline interferon-? was recently licensed for use in veterinary
medicine in some European countries and Japan. Interferons are
species-specific; therefore, feline interferon-? can be used life-long
without stimulating antibody development. No side effects have been
reported in cats. Feline interferon-? is active against FIV in vitro but
so far, only one study has been performed in field cats that did not
show significant changes in survival rate when compared to a placebo
group [de Mari et al. 2004].
Human interferon-a has
immune-modulatory effects, but also acts as a true antiviral compound by
inducing a general antiviral state of cells that protects them against
virus replication [Tompkins 1999]. Two common treatment regimens exist
for use of human interferon-a in cats, SQ injection of high-dose
(104-106 IU/kg q24h) or PO application of low-dose (1 to 50 IU/kg q24h).
When given SQ in high dosage, interferon-a leads to detectable serum
levels. However, it becomes ineffective after three to seven weeks due
to development of neutralizing antibodies [Zeidner et al. 1990]. A
placebo controlled clinical study using dose human interferon-a PO (10
IU/kg daily) prolonged CD4+ T cell survival [Pedretti et al. 2006].
Immune modulators or interferon inducers are widely used
medications in FIV-infected cats. It has been suggested that these
agents may benefit infected animals by restoring compromised immune
function, thereby allowing the patient to control viral burden and
recover from the disease. There is no conclusive evidence from
controlled studies that immune modulators or alternative drugs have any
beneficial effects on the health or survival of asymptomatic or
symptomatic FIV-infected cats. A non-specific stimulation of the immune
system might even be contraindicated in FIV infection as it can lead to
an increase in virus replication caused by activation of latently
infected lymphocytes and macrophages, and therefore can effect a
progression of disease. Hence, unspecific immune modulators with unknown
effects should not be used in FIV-infected cats.