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Seizures are not a
disease entity per se, but instead indicate the presence of an
underlying disorder that results in disruption of the normal
electrical activity of the brain. The most common cause of seizures
in cats involves structural disorders within the nervous system. Functional disturbances are relatively less common and idiopathic
epilepsy, although it does occur, is rare in cats and is diagnosed
only after excluding structural and functional causes of seizures.
The clinical
appearance of seizures may vary, but will be associated with some
degree of change in consciousness or temperament, involuntary limb
movements, muscle twitching, salivation, vocalization, or involuntary
urination and/or defecation. Changes can last from a few seconds to
minutes. Following a seizure cats may be normal or show signs of incoordination, changes in temperament, behavioral changes, blindness,
or confusion for minutes to hours. Some cats will exhibit abnormal
behaviors before a seizure such as hiding, anxiety, pacing, or seeking
attention.
Diagnostic testing
is based on frequency and severity of seizure episodes as well as age
of the patient and history (known diseases, trauma or exposure to
toxins, etc). An in depth evaluation may not be indicated for cats
presenting with a first time seizure, but a thorough history,
including rabies vaccination, is important as well as a detailed
account of the seizure event since signs resembling a seizure can be
seen with heart, vestibular, musculoskeletal, or cerebellar diseases
and even pain.
When seizure
episodes are increasing in severity or frequency, more in depth
diagnostic testing is indicated and will include some or all of the
following:
-
Thorough physical,
neurologic and ophthalmic exams
- Testing for feline leukemia and immunodeficiency viruses.
- Blood chemistry panel, complete blood count, and urinalysis
- Blood pressure measurement in senior patients and those with heart,
thyroid or kidney disease
- Skull
and/or thoracic radiographs to check for trauma, infection, or
metastasis of cancer
- Serum bile acids in young cats
- Serology for infectious diseases such as fungal organisms or
toxoplasmosis
- Referral for CT, MRI or spinal fluid analysis
Antiepileptic drug
therapy is initiated if seizures occur more frequently than once a
month, if there are cluster seizures or status epilepticus. Cats with
normal exams and lab work, but recurrent, frequent, or violent
seizures may be given medication without determining the underlying
cause for the seizures. The current medication of choice for
maintenance therapy is phenobarbital. Blood levels should be checked
after 2 weeks of therapy to assure appropriate dosage. When phenobarbital alone does not acceptably control seizures, diazepam may
be added. Liver enzymes need to be monitored after 5-7 days of
therapy to check for side effects.
Prognosis depends
on identifying and resolving the underlying cause of seizures and
appropriate seizure control in cases where an underlying cause is not
identified. The goal of therapy is to reduce the severity and
frequency of seizures and improve the cat’s quality of life.
By: Sarah Peakheart, DVM
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