Page 811 - Problem-Based Feline Medicine

36 – THE CAT WITH SEIZURES, CIRCLING AND/OR CHANGED BEHAVIOR 803

Prognosis ● Seizures may occur alone or with other signs dur-
ing the active phase of the disease. They may pres-
Good seizure control is often obtained with appropriate
ent with the full spectrum of severity.
anti-epileptic drug therapy. Progression toward
● Delayed onset post-encephalitic secondary epilepsy
intractability may however occur despite adequate
may also occur after a symptomatic or an asympto-
treatment and indicates a poor prognosis.
matic course of the disease.
A steroid-responsive “shaker cat syndrome” similar
FELINE NON-SUPPURATIVE to the “little white dog shaker syndrome” has been
MENINGOENCEPHALITIS*** observed as the only clinical manifestation of the dis-
ease in a few cats.
Classical signs
Systemic signs including fever, inappetence, lym-
● Focal or multifocal CNS signs. phadenopathy and mild hematological abnormalities
● Seizures. (e.g. leukopenia, lymphocytosis, anemia) may some-
● Occasionally, generalized tremors (“shaker times precede or accompany the neurological signs.
cat syndrome”). Ocular signs (e.g. chorioretinitis) may also be seen.

Pathogenesis Diagnosis
A viral infection is suspected even though the condi- CSF analysis may be normal or reveal a mild increase
tion does not appear to be contagious. Signs are usually of the protein concentration (< 0.70 g/L) and/or
confined to a single cat in a household. a mononuclear pleocytosis (< 50 cells/μl) with numer-
● Several feline (e.g. herpesvirus type I) and non- ous small lymphocytes and/or large foamy mononu-
feline (e.g. arboviruses) viruses may infect the clear cells.
CNS of cats and produce a subclinical or clinical
Brain imaging (MRI) may be normal or show
meningoencephalitis.
inflammatory lesions with contrast uptake. Obstructive
An immune-mediated process is also possible. This or compensatory hydrocephalus and porencephalic
can be primary (idiopathic autoimmune) or secondary (cystic) lesions may sometimes be seen.
to various antigenic stimulation such as vaccination,
CNS infection with a non-pathogenic virus or infection Differential diagnosis
in another system.
Other infectious encephalitis (e.g. FIP, toxoplasmo-
Cats of any age and with or without outdoor access
sis, cryptococcosis) when there are other systemic
may be affected.
signs, ocular involvement or a progressive course.
● CSF analysis is the best test to differentiate the dis-
Clinical signs ease from FIP. Cats with FIP usually have a higher
CSF protein concentration and cell count with a pre-
The clinical course is variable with an acute or insid- dominance of neutrophils (see page 844). Toxoplas-
ious onset and a static, progressive or regressive mosis can however produce similar CSF changes.
course. Rarely, cryptococcosis may produce only mild CSF
inflammation but culture and titers help with diagno-
The disease can produce focal or multifocal signs of
sis when the organism is not visible in the CSF.
variable severity attributable to any portion of the
Usually signs are rapidly progressive with crypto-
CNS; central vestibular (head tilt, balance losses,
coccosis.
mental depression, postural reaction deficits), spinal
cord (hindlimb proprioceptive ataxia and paresis), Other causes of seizures in cats should be considered
cerebellar and cranial nerve signs are most common when seizures are the only sign of the disease (e.g. idio-
and may occur alone or in any combination. pathic and likely symptomatic epilepsies).