Page 852 - Problem-Based Feline Medicine

844 PART 10 CAT WITH SIGNS OF NEUROLOGICAL DISEASE

Prognosis compulsive walking and decreased menace are some of
the signs that may be observed.
Removal of the polyp by a ventral bulla osteotomy
minimizes the risk of recurrence. Recurrence is fre- Clinically, the disease frequently appears to be focal,
quent using oral or aural access to the polyp. although this is not the case at postmortem.

The head tilt usually remains but the other vestibular The head tilt is always associated with somnolence,
signs (ataxia and nystagmus) usually resolve. with or without cerebellar signs, because the cerebel-
lum is closely situated.
If facial paralysis is present, ipsilateral deviation of the
face ensues. Chorioretinitis may be present (see The Blind Cat or
Cat with Retinal Lesions).
If a Horner’s syndrome is present, it usually improves
and the residual deficit (aniscoria) is of no clinical Diagnosis
significance.
The history of a young cat originating from a multi-
cat household or breeder, with a protracted disease,
FELINE INFECTIOUS PERITONITIS**
vague systemic signs and neurological abnormalities
raises the index of suspicion for FIP.
Classical signs
The cerebrospinal fluid analysis on its own is not sen-
● Head tilt in a cat systemically ill for a few
sitive for a diagnosis of FIP.
weeks.
● Cell counts and protein concentration can be within
● Non-specific systemic signs such as fever,
reference range especially if the disease is focal.
weight loss and lethargy.
Typically, there is a moderate to severe pleocytosis,
● Chronic progressive disease.
with mononuclear cells or neutrophils as the pre-
● There may be neurological deficits other
dominating cell type, and a marked increase in pro-
than a head tilt.
tein concentration.
● Protein concentration > 2 g/L increases the like-
See main references on page 372 for details (The
lihood of FIP.
Pyrexic Cat).
MRI scan of the brain is helpful, as frequently there is
periventricular enhancement suggestive of ependymi-
Pathogenesis
tis, and hydrocephalus with ventricular dilatation. The
The causative virus is a macrophage-tropic mutant of MRI findings are more representative of the neu-
the ubiquitous feline enteric coronavirus. ropathological extent of the disease than is the clinical
presentation, which is often focal in nature.
The clinical disease results from an immune-mediated
response of the host to macrophage-infected feline infec- Hematology and chemistry abnormalities are non-
tious peritonitis virus (FIPV). The severity of the disease specific except for a high serum total protein concen-
is based on host susceptibility and strain virulence. tration, which is frequent.
The anti-coronavirus IgG titer in CSF is consistently
positive.
Clinical signs
The polymerase chain reaction (PCR) test detects the
Affected cats are usually less than 3 years of age and
presence of feline coronaviruses but is not specific to
from large multiple-cat households or breeders.
FIP coronavirus.
The most common non-specific systemic signs are
Immunohistochemistry and immunocytochemistry are
fever, weight loss and lethargy.
techniques which appear promising for diagnosis of
Thirty-five percent of the cats with FIP have neuro- FIP. They use monoclonal antibody targeted against
logical signs. These vary with the lesion location. feline coronavirus to demonstrate coronavirus within
Behavioral changes, head tremor, seizures, depression, macrophages in tissue or effusions. The concentration