Page 1519 - Small Animal Internal Medicine, 6th Edition

CHAPTER 96 Polysystemic Viral Diseases 1491

uniformly successful antiviral treatment has been developed, to FIPV develop the syndrome of FIP. However, some
and the drugs typically have potentially serious adverse research cats that survived FIPV infection on primary expo-
VetBooks.ir effects. Cyclosporine A inhibits replication of feline corona- sure developed FIP on subsequent inoculation suggesting
that immunity is not permanent (Addie et al., 2001; Peder-
viruses in vitro, but it is currently unknown whether this
drug can be used successfully as a treatment of FIP (Tanaka
is complex, cats with progeny that died of FIP should be
et al., 2012). Small interfering RNA (siRNA) can be synthe- sen et al., 2014a). Although the genetics of FIPV resistance
sized and target different regions of the coronavirus genome avoided for use for breeding programs in pedigreed catteries
to inhibit viral replication in vitro and is another potential (Pedersen et al., 2014).
future treatment modality (McDonagh et al., 2011). An intranasally administered, mutant strain of coronavi-
Because disease from FIP is secondary to immune- rus that induces mucosal immune response but minimal
mediated reactions against the virus, modulation of the systemic immune response is available in some countries
inflammatory reaction is the principal form of palliative (Primucell FIP, Zoetis Animal Health). This strain does not
therapy. Low-dose prednisolone (1-2 mg/kg orally [PO] induce FIP; the majority of cats with adverse effects have
q24h) may lessen clinical manifestations of noneffusive FIP. exhibited only mild signs associated with placement of liquid
However, the use of immunosuppressive drugs is controver- in the nares, and the vaccine does not appear to potentiate
sial because cats with FIP have impaired immune responses. antibody-dependent enhancement of virus infectivity when
Prednisolone and feline recombinant interferon were used administered to previously seropositive cats. The vaccine
in combination for the treatment of both effusive and nonef- appears to be effective in at least some cats, but whether it
fusive FIP in small numbers of cats (Ishida et al., 2004). In protects against all field strains, mutations, or recombinants
that study, four cats with effusive disease believed to be from is unknown, so it is considered as noncore by the American
FIP virus had prolonged remission. It is impossible to deter- Association of Feline Practitioners (see Chapter 93). Zoo-
mine whether the effect was from the prednisolone or inter- notic transfer of FIP virus or FECV to human beings has not
feron because both drugs were administered to all cats. In been documented.
another study, administration of interferon-ω was ineffective
for the treatment of FIP (Ritz et al., 2007). In the future,
veterinarians may be able lessen inflammation and disease FELINE IMMUNODEFICIENCY VIRUS
induced by FIP by administering anti-feline tumor necrosis
factor monoclonal antibodies (Doki et al., 2016). Immune Etiology and Epidemiology
modulation with polyprenyl immunostimulant may induce FIV is an exogenous, single-strand RNA virus in the family
beneficial effects in some cats with noneffusive FIP (Legen- Retroviridae, subfamily Lentivirinae. The virus is morpho-
dre and Bartges, 2009; Legendre et al., 2017). logically similar to the human immunodeficiency virus
Antibiotics do not have primary antiviral effects but may (HIV), but it is antigenically distinct. Like FeLV, FIV pro-
be indicated for the treatment of secondary bacterial infec- duces reverse transcriptase to catalyze the insertion of viral
tion. Other supportive care treatments such as anabolic RNA into the host genome. Multiple clades of the virus exist,
steroids (stanozolol, 1 mg PO q12h), aspirin (10 mg/kg PO and some isolates have differing biologic behavior. For
q48-72h), and ascorbic acid (125 mg PO q12h) have also example, immune deficiency is induced much more quickly
been recommended for the treatment of FIP. Most cats with by some isolates, and clinical diseases such as uveitis are
systemic clinical signs of FIP die or require euthanasia within induced by some but not all isolates. The prevalence of FIV
days to months of diagnosis. The effusive form of disease antibodies in United States and Canada was 3.6% in a 2017
carries a grave prognosis. The drug propentofylline, used to study (Burling et al., 2017), which is higher than the 2.5% in
treat vasculitis, was evaluated in a placebo-controlled study a study reported in 2006 (Levy et al., 2006). Regional varia-
of naturally infected cats with effusive disease. However, tions in prevalence rates for both FIV and FeLV exist (Chhetri
the propentofylline protocol assessed did not improve the et al., 2013).
quality of life or lessen the effusion (Fischer et al., 2011). FIV replicates readily in the oral lymphoid tissues (Miller
Depending on the organ system involved and the sever- et al., 2017). Aggressive biting behavior is thought to be the
ity of polysystemic clinical signs, cats with noneffusive FIP primary route of transmission of FIV; older, male, outdoor
have variable survival times. Cats with only ocular FIP may cats with clinical signs of disease are most commonly
respond to antiinflammatory treatment or enucleation of the infected. Plasma viral loads increase as the FIV disease
affected eye(s) and have a better prognosis than cats with severity increases (Kann et al., 2014). Vertical transmission
systemic FIP. appears to be unlikely to occur based on a study of group
housed shelter cats (Litster et al., 2014). FIV is present in
Prevention and Zoonotic Aspects semen and can be transmitted by artificial insemination.
Prevention of coronavirus infections is best accomplished by Transplacental and perinatal transmission occurs from
avoiding exposure to the virus. Although viral particles coro- infected queens to kittens. Arthropod transmission appears
naviruses can survive in dried secretions for up to 7 weeks, to be unlikely. Transmission by routes other than biting is
routine disinfectants inactivate the viruses. Some cats elimi- less common because high levels of viremia are of short
nate FECA coronavirus infections, and not all cats exposed duration. FIV infection of cats has worldwide distribution,