Page 820 - Problem-Based Feline Medicine

812 PART 10 CAT WITH SIGNS OF NEUROLOGICAL DISEASE

Treatment Serology from blood, CSF, aqueous humor and urine is
highly specific and sensitive.
No treatment is effective once neurological signs are
present. Glucocorticosteroid may temporarily improve Identification of the organism may be made by cytol-
the neurological signs. ogy, histology or culture of various body fluids and tis-
sues including CSF, nasal discharge and polyp-like
masses, skin lesions, enlarged lymph nodes.
CRYPTOCOCCOSIS**
Differential diagnosis
Classical signs
Other infectious encephalitides such as FIP and toxo-
● Chronic nasal discharge, often with nasal
plasmosis need to be differentiated from cryptococco-
distortion.
sis. With cryptococcosis the organism is usually
● Cutaneous lesions – nodules or ulcers.
evident in CSF, although occasionally culture may be
● Occasionally, ocular and CNS signs.
required to demonstrate it.
See main reference on page 19 for details (The Cat
With Signs of Chronic Nasal Disease). Treatment
Fluconazole (2.5–10 mg/kg PO q 12 h) is best for CNS
infections, or itraconazole (5 mg/kg PO q 12 h). See
Pathogenesis
main reference on page 26 for treatment details.
Infection is by inhalation of the organism contained
in high concentration in soil contaminated by pigeon Prognosis
droppings or eucalyptus tree debris.
The prognosis is guarded once CNS involvement
CNS infection occurs by direct extension through the
occurs.
cribriform plate or by hematogenous spread. A diffuse
or focal granulomatous meningoencephalitis results.
INTOXICATIONS**
Clinical signs
Classical signs
CNS signs can occur alone or with other signs (e.g.
● Signs of CNS, autonomic or neuromuscular
rhinitis, cutaneous lesions) and are usually rapidly pro-
stimulation or depression.
gressive.
● Rarely and terminally, convulsive status
● Most commonly, cats exhibit cerebral signs such
epilepticus.
as mental depression, behavioral changes, cir-
cling, head pressing and ataxia; seizures may occur
with forebrain involvement but are unlikely to be Pathogenesis
the only sign.
Signs of intoxications usually occur shortly after acute
● Blindness with dilated and unresponsive pupils may
and accidental ingestion or topical contact. Cats’ selec-
occur due to optic neuritis.
tive eating behavior is protective but their grooming
Ocular signs including chorioretinitis, panophthalmi- habits may increase exposure.
tis, and retinal detachment are often associated with
Most intoxicants cause functional disturbances for
CNS involvement.
example conduction failure or neurotransmitter imbal-
ance in various portions of the nervous system,
Diagnosis although others cause structural damage.
CSF analysis may reveal mild to marked inflammatory Intoxicants that may cause seizures include the fol-
changes, often with numerous cryptococcal organisms. lowing: