Page 937 - Clinical Small Animal Internal Medicine

86 Feline Coronavirus 875

(feces, blood, effusion, cerebrospinal fluid [CSF], tissue, three cats with mild dry FIP, with two cats still alive after
VetBooks.ir and saliva) with high sensitivity. However, as with anti- two years of the diagnosis. However, follow‐up studies
suggested no benefit in cats with more severe forms of
body tests, distinction of FECV from FIPV is not possi-
ble at this time. The finding of virus in blood or tissue
authors.
also does not confirm FIP because FECV may be ampli- the disease and its use is not recommended by some
fied from these tissues in cats without FIP. A quantitative Recent studies by Pedersen et al. have focused on anti-
PCR test for blood, effusion, and tissue is available. The viral therapy. Initially, the investigators performed a
test is based on the hypothesis that replicating virus in study using a 3C protease inhibitor (GC376) which
peripheral blood and tissues suggests FIPV rather than showed some success in treating cats with FIP. Although
FECV. However, because viremia also occurs with FECV 19 of 20 cats recovered, disease relapse occurred and 18
infection, healthy cats may also test positive using this months after infection only six cats remained disease
assay. free. In another study, a small molecule nucleoside
analog, GS441524, was used in 10 infected cats who
were successfully treated and healthy eight months after
Histopathology and Immunostaining
treatment, with two cats requiring a second treatment
Relatively distinctive inflammatory infiltrates associated after initial relapse. This nucleoside analog works by act-
with FIP are characterized by variable degrees of severity ing as an alternative substrate for the viral RNA poly-
and contain a combination of macrophages, lympho- merase terminating replication. These studies are
cytes, and plasma cells, mixed with lesser numbers of promising developments for future clinical trials and
neutrophils. The hallmark of the histopathologic lesions treatments.
is a granulomatous to pyogranulomatous reaction with
vascular orientation and vasculitis. Detection of intracel-
lular FCoV antigen in macrophages in effusions by Prognosis
immunofluorescence, or in tissue by immunohistochem-
istry, can confirm the diagnosis, and is considered the With the development of FIP, prognosis is poor to grave,
gold standard if properly performed. Immunostaining with a reported median survival time of 49 days.
may be falsely negative if virus is not present in a given Euthanasia should be considered especially when quality
sample or if antibodies do not cross‐react with a particu- of life is poor and there is no response to therapy within
lar strain. a short period of time. However, newer research indi-
cates that antiviral therapy might be successful in cats
with complete reversal of clinical signs (see earlier).
Therapy

Supportive care and reducing stress are important. Prevention
Specific treatment has been primarily focused on reduc-
ing the inflammatory and hyperimmune response to the
virus. Unfortunately, increased survival has not been The formation of antibody enhances disease, so develop-
proven with any of these interventions. Of the immuno- ment of an effective vaccine is difficult. At the time of
suppressants, prednisolone at immunosuppressive doses writing, the available vaccine is not recommended by the
is currently the most consistently recommended. American Association of Feline Practitioners. Reducing
Although prednisolone may induce remission in some stress and overcrowding, cleaning litterboxes daily,
cats, treatment is not curative and may only slow the avoiding fecal–oral contact by keeping litterboxes away
progression of the disease. Other immunosuppressive from food and water dishes, and separating newly
drugs such as chlorambucil have been used in combina- acquired cats and cats suspected of being infected are
tion with prednisolone but the risk:benefit ratio and effi- recommended husbandry practices.
cacy are unknown. Feline interferon‐omega treatment is
an immunomodulatory therapy that may be considered
to treat FIPV‐infected cats, though studies show differ- Public Health Implications
ences in efficacy. Similarly, a recent study showed that
the immunostimulant polyprenyl extended the life of Feline coronaviruses are not thought to infect humans.