Seizures are the result of the abnormal activity of neurons in the
brain and are relatively common in veterinary patients. Seizure
events are usually brief (1-2 minutes) and self-limiting, but some
animals may have prolonged activity (status epilepticus; seizures
lasting more than 5 minutes) or runs of seizures over a less than
24 hour period (cluster seizures). Status epilepticus and cluster
seizures are particularly concerning and can result in death as
they lead to increased body temperature and metabolic changes
within the body.
Classically, seizures are manifest by the loss of consciousness,
involuntary convulsions, salivation, urination, and increased heart
rate. However, some animals with seizures will not exhibit all of
the classical clinical signs, making seizures sometimes challenging
to recognize and diagnose.
There is a variety of causes for seizures in animals.
Veterinarians often divide the causes of seizure activity into
those that arise from physical problems within the brain (for
example tumors or brain inflammation), metabolic issues outside the
brain that make seizures more likely or idiopathic causes (genetic
problems with chemicals in the brain).
Physical examination, neurological examination, blood work, MRI,
and spinal fluid analysis are often used to discern the cause of
seizure activity. While reducing the frequency of seizures is very
important, ignoring potential underlying causes for seizures is not
Management of seizures will not necessarily eliminate all seizure
activity, but it should decrease the frequency and severity of the
events. Traditionally, Phenobarbital and potassium bromide have
been used to control seizures in veterinary patients. While these
drugs are very effective in most animals and relatively
inexpensive, the side effect profile is felt to be greater than
newer anti-seizure drugs. Phenobarbital and bromide do require
careful patient monitoring of drug levels and body systems.
Animals on Phenobarbital should have liver function tests (bile
acids or ammonia), complete blood count, and serum biochemistry
performed prior to initiating treatment and when blood drug levels
Additionally, we suggest periodic blood work re-checks every six
months as Phenobarbital can lead to liver dysfunction and bloodline
alterations. Blood drug levels are also performed 14-21 days after
the Phenobarbital dose is changed.
Drug levels are usually acquired 2-4 months after initiating
therapy due to the long half-life and every 6 months thereafter.
Animals that are experiencing unregulated seizure activity will
need blood drug levels promptly.
Animals that frequently experience cluster or status events are
often provided with diazepam (Valium) to administer rectally to
halt events. Additionally, anti-seizure drugs with a short
half-life (e.g. gabapentin or levetiracetam) can be administered as
“pulse” treatment to shorten cluster events.
Most Frequently Affected Breeds