FeLV-infected cats should be confined strictly indoors to prevent spread to other cats in the
neighbourhood. There may also be benefits in preventing exposure of the immune-suppressed
retrovirus-infected cat to infectious agents carried by other animals. This is true in the home
environment as well as in the veterinary hospital. Although they can be housed in the same
ward as other hospitalized patients, they should be housed in individual cages. It should be
considered that they may be immune-suppressed and should be kept away from cats with
other infectious diseases. They should not be placed in a "contagious ward" with cats
suffering from infections such as viral respiratory disease.
The management of the cat should be adjusted to minimise potential exposure to other
infectious agents. As well as confining the cat indoors it may be prudent to avoid feeding
uncooked meat, which may pose a risk of bacterial or parasitic infections to which FeLVpositive
cats are more susceptible.
Asymptomatic FeLV-infected cats should receive clinical check-ups ideally at least every six
months. A complete blood count (CBC), biochemistry profiles and urinalyses should be
performed periodically, ideally every six to twelve months.
Intact male and female retrovirus-infected cats should be neutered to minimize the risk of
virus transmission and for health benefits. Surgery is generally well tolerated by
asymptomatic FeLV-infected cats. The virus is infectious only for a short while outside the
host [Francis et al., 1979b], and is sensitive to all disinfectants including common soap;
simple precautions and routine cleaning procedures will prevent transmission in the hospital.
Routine vaccination in FeLV-infected cats is subject of discussion. Vaccination programmes
to prevent common infectious diseases should be maintained in FeLV-infected cats, although
it has been demonstrated that FeLV-infected cats may not be able to mount adequate immune
response to rabies vaccination [Franchini, 1990]. Therefore, protection in a FeLV-infected cat
after vaccination may not be comparable to that in a healthy, uninfected cat and so if cats are
allowed to go outside – which is not recommended, certainly never in rabies-endemic areas -more frequent vaccination may need to be considered. Inactivated vaccines are recommended
whenever available as in immune-suppressed cats, modified live virus vaccines may retain
some pathogenic potential and cause clinical disease.
If FeLV-infected cats are sick, prompt and accurate identification of specific diseases
affecting the cat is important 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 retrovirus infection
respond well to appropriate medications although a longer or more aggressive course of
therapy (e.g., antibiotics) may be needed than in retrovirus-negative cats. Corticosteroids,
other immune-suppressive or bone marrow-suppressive drugs should generally be avoided,
unless used as a treatment of FeLV-associated malignancies or immune-meditated disease.
Good veterinary care is important for FeLV viraemic cats. Many may need fluid therapy.
Some specific disease complications of FeLV infection may respond to treatment, such as
secondary bacterial infections, especially with Mycoplasma haemofelis which often responds
to doxycycline. If stomatitis/gingivitis is present, corticosteroids should be considered to
increase the food intake. Blood transfusions may be useful in anaemic cats and in the case of
leukopenia, granulocyte colony-stimulating factor (G-CSF) can be considered [Fulton et al.,
1991]. Treatment regimes for lymphomas, particularly based on chemotherapeutic drugs, are
now well established. Some cases of lymphoma respond well to chemotherapy with remission
expected in most cases and some cats showing no recurrence within two years. Chemotherapy
of FeLV positive lymphomas will not resolve the persistent viraemia and the outlook for such
cats is not good [Ettinger, 2003].
There is little evidence from controlled studies to support the efficacy of immune modulators
on the health or longevity of FeLV-infected cats.
Nevertheless, it has been suggested that some of these agents may benefit infected animals by
restoring compromised immune function, thereby allowing the patient to control its viral
burden and recover from the disease. Although reports of uncontrolled studies frequently
suggest dramatic clinical improvement (e.g., when using so-called “paramunity inducers”);
these effects were not observed, in subsequent controlled studies [Hartmann et al., 1998].
Staphylococcus Protein A, SPA, is a bacterial polypeptide purified from cell walls of
Staphylococcus aureus Cowan I that acts as an immune modulator. In a placebo-controlled
study, treatment of ill, client-owned FeLV-infected cats with Staphylococcus Protein A (10
µg/kg twice per week for up to ten weeks) did not cause a statistically significant difference in
FeLV status. However, it did result in a significant improvement in the owners’ subjective
impression of the health of their pets [McCaw et al., 2001].
Occasionally, antiviral drugs are used; however, their efficacy is limited and many of these
compounds have severe side effects in cats [Hartmann, 2006]. There are only a few controlled
studies that have demonstrated some effect of a few drugs in FeLV-infected cats.
Treatment of FeLV viraemia with feline interferon omega (interferon-?) was shown to
significantly improve clinical signs and to extend the survival time of FeLV viraemic cats,
although it did not lead to reversion of viraemia [de Mari et al., 2004]. Feline interferon-?
inhibits FeLV replication in vitro. In a placebo-controlled field study, 48 cats with FeLV
infection were treated with interferon-? (106 IU/kg SQ q24h on five consecutive days
repeated three times with several weeks between treatments) [de Mari et al., 2004]. A
statistically significant difference was found in the survival time of treated versus untreated
cats. No viral parameters, however, were measured throughout the study to support the
hypothesis that the interferon actually had an anti-FeLV effect rather than inhibited secondary
infections, and further studies are needed.
An antiviral compound routinely used is 3’-azido-2’,3’-dideoxythymidine (AZT), a
nucleoside analogue (thymidine derivative) that blocks the reverse transcriptase of
retroviruses. It has been shown that AZT effectively inhibits FeLV replication in vitro and in
vivo in experimental infections. It can reduce plasma virus load, improve the immunological
and clinical status, increase quality of life, and prolong life expectancy in some FeLVinfected
cats. It should be used at a dosage of 5 - 10 mg/kg q12h PO or SC. The higher dose
should be used carefully in FeLV-infected cats as side effects (e.g., non-regenerative anaemia)
can develop [Hartmann, 2005].