Page 380 - Problem-Based Feline Medicine

372 PART 7 SICK CAT WITH SPECIFIC SIGNS

Genetic predisposition appears to play a role.
FELINE INFECTIOUS PERITONITIS
(FIP)*–*** FIP is most common in catteries and multi-cat house-
holds.
Classical signs
● Fever. Clinical signs
● Weight loss, anorexia.
● Lethargy. There are two clinical forms of FIP, effusive or wet
● Abdominal effusion. form and non-effusive or dry form. Both are charac-
● Dyspnea from pleural effusion. terized by a fluctuating fever unresponsive to anti-
● Ocular and/or neurologic signs. biotics, anorexia, lethargy and weight loss.
● Hepatic, intestinal and/or renal signs.
Typical age of onset is 6 months to 2 years, but any
age can be affected.
Pathogenesis The effusive form may have any of the following signs:
● Abdominal effusion that is non-painful but pro-
Feline coronaviruses (FCoV) are divided into:
gressive. The amount of effusion varies from vol-
● FIP-inducing strains, which are mutated strains
umes causing abdominal enlargement, to amounts
that infect macrophages and can be distributed to
only detectable by abdominocentesis. Fluid is
many organ systems.
straw-colored and highly viscous, like egg white.
● Feline enteric coronavirus (FECV) which are
● Pleural effusion resulting in dyspnea occurs in
mildly pathogenic strains producing signs limited
30% of cats with the effusive form. Pericardial
to the intestinal lumen.
fluid may be evident on ultrasound. Usually it not
Mutations of FECV that lead to FIP can occur in the associated with clinical signs, but occasionally can
host within about 18 months of contracting the virus. produce cardiac tamponade.
● Male cats may present with scrotal swelling.
The chance of developing FIP decreases the longer the
cat has high coronavirus titers. The non-effusive form may have any of the following
signs:
Immune responses play a large role in the develop-
● Ocular signs result from pyogranulomatous
ment of this disease:
inflammation of the iris and ciliary body. They
● If a cell-mediated response is not mounted
include bilateral uveitis, perivascular exudates
to mutated FCoV, effusive FIP generally results,
(cuffing), retinal hemorrhage, retinal detachment.
producing abdominal, thoracic, pericardial and/or
● Neurologic signs include cerebral and cerebellar-
scrotal effusions.
vestibular signs such as seizures, personality
● A partial cell-mediated response to mutated
changes, nystagmus, head tilt, circling, head tremor
FCoV generally results in non-effusive FIP, and
and hyperesthesia.
clinical signs are due to formation of granulomas,
● Dysfunction of any organ system may result from
with signs depending on the organ affected.
granuloma formation within the tissue of that
● A strong cell-mediated response results in clear-
organ, e.g., liver, kidney, spleen, intestines, lungs,
ance of the virus.
etc., however, organ failure producing clinical signs
Stress may contribute to development of disease, as only rarely occurs, and most dysfunction is only
stress can interfere with the immune response. detected on biochemical tests.
Multiple-cat households, surgery, illness and pregnancy ● Granulomatous masses may be palpable in abdom-
may be part of the history in a cat with clinical signs of inal viscera especially mesentery, mesenteric lymph
FIP. nodes and omentum as tender, irregular masses.
Occasionally vomiting or diarrhea results from
Typically, cats have been in multi-cat environments
extensive lesions on the bowel wall.
(cat breeders or rescue facilities) within the previous
year. Jaundice may occur with either form of the disease.