What are seizures?
Also known as convulsions or fits, seizures are the result of a sudden and uncontrolled burst of electrical activity within the brain. They are one of the most common neurological disorders in cats, although the prevalence is much lower than that of dogs. Seizures occur in the cerebrum, which is located in the front of the skull. It is responsible for sensory and neural functions as well as behaviour.
Cats of any age can be affected by seizures, however as many of the underlying causes (listed below) occur more frequently in older cats, seizures tend to be seen more often in the ageing cat population. It is believed around 0.5 - 1% of cats are affected by seizures.
Seizures fall into two categories:
Tonic-clonic seizures - Formerly known as generalised or grand mal seizures, tonic-clonic seizures are a type of seizure that affects the entire brain.
Focal seizures - Aso known as partial or local seizures, focal seizures are restricted to one location in the brain. Focal seizures are further divided into simple focal or complex focal. Simple focal seizures are when consciousness remains, complex focal seizures are when there is a change or loss of consciousness.
What causes seizures in cats?
Any disease which alters the way the brain functions can potentially cause seizures. Epilepsy is the most common cause of seizures in cats and is defined as recurring seizures resulting from an intracranial cause (see below). It calls into two categories:
- Inherited, acquired or idiopathic (no known cause)
- Symptomatic epilepsy
Causes of seizures may be extracranial (problems occurring outside the brain) or intracranial (problems occurring inside the brain).
Some common causes of seizures include:
- Brain tumour, benign or cancerous (meningioma, glian cell tumours, and lymphoma)
- Head trauma
- Hydrocephalus (water on the brain)
- Brain infections or inflammation such as meningitis and encephalitis
- Bleeding into the brain
- Abnormal migration of heartworm
Intracranial diseases are the most common causes of seizures in cats.
- Heat stroke
- Portosystemic shunt
- Bacterial or viral infection (FIP, FeLV)
- Fungal infection (blastomycosis cryptococcosis)
- Kidney failure
- Liver disease can cause a build-up of toxins in the body, which can lead to seizures
- Certain medications
- Poisoning - Common causes of poisoning include antifreeze, lead, insecticides, marijuana, zinc, pseudoephedrine, chocolate, flea products
- Hypertension (high blood pressure)
- Metabolic disorders - Hypoglycemia (low blood sugar), hyperglycemia (high blood sugar), uremia, hypercalcemia (high blood calcium), hypocalcemia (low blood calcium), hypothyroidism
- Feline ischemic encephalopathy
- Lysosomal storage disease
- Thiamine deficiency
- Systemic lupus erythematosus
What are the symptoms of seizures in cats?
Symptoms can vary depending on the severity of the seizures as well as the underlying cause. Nonspecific signs may include unusual behaviour, lethargy, anorexia. There may be accompanying symptoms if there is an underlying cause.
Focal seizures affect only part of the body (for example the face), whereas clonic tonic seizures affect the entire body. Most seizures last between 5 - 60 seconds but may be longer.
Seizures come in three phases known as preictal phase (also known as aura), ictal phase and postictal phase.
Common symptoms of seizures may include:
- Involuntary vocalisation/calling out
- Muscle twitching
- Rigid extension of the legs
- Loss of consciousness
- Involuntary urination and/or defecation
- Loss of breathing
- Salivation/foaming at the mouth
- Champing or chewing
There may be subtle signs in your cat prior to him having a seizure. Mild changes in behaviour, pacing, crying, clinginess and attention seeking.
Immediate care of your cat during a seizure:
Please be aware that while (and often after) a seizure has occurred, your cat may not be aware of his surroundings and it is common for him to not respond to, or recognise you. His actions are involuntary and it is important you keep a safe distance from him as it is possible you may get injured.
- If you suspect your cat is having a seizure, stand aside until the seizure abates.
- Remove objects which may harm your cat such as furniture.
- If there is a risk of falling (such as being close to stairs), carefully move your cat out of danger.
- Do not try to force your fingers or objects into your cat's mouth to prevent choking on the tongue. It is not possible for this to occur.
- Make a note of how long the seizure lasts, symptoms and behaviour before, during and after the seizure. This will be very helpful to your vet.
- Remember, once the seizure has finished, it is very common for your cat to be disoriented and confused.
As soon as the seizure is over, take your cat to a veterinarian. Seizures lasting longer than five minutes are an immediate danger and veterinary attention should be sought urgently.
How are seizures in cats diagnosed?
Your veterinarian will perform a complete physical and neurological examination of your cat. He will obtain a medical history from you including onset of symptoms, how many seizures your cat has had, any medications or poisons your cat could have ingested (accidentally or given by the owner), any recent accidents or illnesses, when your cat was last vaccinated. Diagnosis is difficult unless your veterinarian sees your cat having an actual seizure at his practice. There is no test to diagnose seizures in cats.
Diagnostic tests will need to be performed to determine an underlying cause. These may include:
- Biochemical profile, complete blood count, and urinalysis to evaluate the overall health of your cat and evaluate how the liver and kidneys are functioning.
- Imaging of the brain such as CT or MRI scan.
Additional tests may be required depending on your veterinarian's index of suspicion as to the underlying cause, this may include:
- Antigen testing for certain infections.
- Ultrasound to check for a portosystemic shunt.
- Specific blood tests if poisoning is suspected.
- Fecal examination to look for the presence of parasites.
- Bile acid test to measure the performance of the liver.
- Metabolic screen to look for abnormal metabolites in the cat's urine. This may indicate lysosomal storage disease.
- Cerebral spine fluid (CSF) analysis to check for encephalitis (inflammation of the brain).
In some cases, a cause can not be determined, in which case your cat will be diagnosed with primary or idiopathic seizure disorder.
How are seizures in cats treated?
The goal of treatment for seizures is to find the underlying cause and treat it. Some conditions are completely reversible (such as lead poisoning, low blood sugar, certain infections for example), and once this has occurred then the seizures should stop completely. Other conditions may be managed, but not completely eliminated, if a head trauma has occurred causing brain damage or some brain tumours which are inoperable. If this is the case, your cat may be put on anti-convulsant medications such as Phenobarbital. This medication can cause some side effects including ataxia, increased appetite, thirst, and urination.
If your cat is presenting with a seizure, your veterinarian may give your cat medication such as Valium to stop a prolonged seizure.
It is quite common for a cat who has had one seizure to have repeat seizures at a later date. It is advised you keep your cat indoors or give him access to a cat enclosure, to keep him safe.
If your cat is prescribed anticonvulsant medications, administer as instructed.
Regular follow-ups will be necessary to ensure the medication is working and it is not causing any side effects.