Seizures in Cats

Seizures and epilepsy are less commonly encountered in cats than dogs. They are, however, the most common sign of disease affecting the front part of the brain in the cat.

Some important terms:-

Seizure (convulsion, ictus, fit) - an involuntary disturbance of normal brain control which is usually seen as uncontrollable muscle activity. Seizures can be single and very occasional or may occur in clusters followed by long periods (weeks to months) without fitting.

Epilepsy describes recurrent seizures.

Preictal (aura) - the change in character that may occur prior to a fit e.g. nervousness, attention seeking, head turning.

Postictal. Following a seizures it can take 24-48 hours for a cat to return to normal. This period is called the postictal phase and is characterised by a variety of signs including sleepiness, pacing, depression, excitement, excessive eating and drinking.

Generalised seizures (= a grand mal seizure) - jerking movements, rigid limbs, paddling/running movements, loss of faecal and urinary control. The head is often bent backwards along the spine.

Status epilepticus describes continuous fitting for more than 5-10 minutes or repeated seizures without full recovery in between.  Cats in status require immediate treatment.

Partial seizures are less commonly recognised may but are when  only certain muscle groups are involved, or may be characterised by behavioural changes (e.g. tail chasing, biting at imaginary objects, aggression).

Seizures often occur at times of changing brain activity e.g. during phases of sleep, excitement or feeding. Affected cats can appear completely normal in between fits. Many different diseases can lead to seizures, either diseases outside of the brain such as some liver diseases, low blood glucose or calcium levels, or ingestion of particular toxins, or diseases within the brain such as an infection, tumour, trauma or developmental abnormality. It is therefore important that diagnostic tests are performed to try to discover the cause of the fitting as treatment of the underlying disease is most likely to lead to successful control of the seizures. Idiopathic epiliepsy is the term used to describe when no underlying cause for the seizures is identified.

How can I help my veterinary surgeon to make a diagnosis?

Carefully observing your cat particularly at the beginning of a fit can provided very valuable information to your veterinary surgeon about the types of disease that may be causing the problem.

1.  Age at which fits began, are they getting worse

2.  Chronicity - i.e. are the seizures intermittent or did they develop suddenly

3.  Frequency, multiplicity of seizures

4.  Association of seizures i.e. asleep, excitement, feeding

5.  Other signs of ill health e.g. poor appetite, excessive drinking, reduced exercise

Information about your cat's lifestyle may also be important

6.  Medication use - especially recent worming or use of flea control products

7.  Diet

8.  Access to poisons

Both diseases which involve the brain directly (intracranial) and conditions which affect other body systems (extracranial) can cause fitting.  Some underlying conditions can be treated and cured so it is worth having your cat investigated thoroughly.

How can a diagnosis of the cause of the seizures be made?

A range of tests are often needed before a final diagnosis can be made, initially this is likely to involve blood samples to look for extracranial causes of the fitting. Some of these blood tests are not “routine”; and test for exposure to toxins such as lead or infectious diseases such as toxoplasma and fungal infections. Because these tests are not routine it may take several days to get a result. If all these tests are negative then your vet may suggest referral to a specialist to perform more advanced testing. 

"A range of tests are often needed before a final diagnosis can be made, initially this is likely to involve blood samples to look for extracranial causes of the fitting."

As the brain is a very protected organ radiographs and ultrasound of the head may be of little benefit. Other tests that can be useful including sampling the fluid that surrounds the brain (cerebrospinal fluid - CSF) and advanced imaging of the brain. CSF analysis is sometimes non-specific but can be useful for the diagnosis of certain infectious diseases and specific types of cancer. Advanced imaging of the brain by magnetic resonance imaging (MRI) and computed tomography (CT) are usually available at specialist centres only. They are extremely sensitive tests and very useful in making a specific diagnosis, but do not always change what we can do for your cat. In cases of idiopathic epilepsy all these tests will be negative/normal, meaning you may need to manage your cat’s seizures with medications for the rest of its life.

What treatments are available?

It is important that a cat which has had multiple seizures in a short space of time receives treatment even if the cause is not yet clear. The reason for this is that the brain “learns” to fit and the more fits your cat has, the more the brain will be prone to fitting in the future. There are too many underlying causes of fits to be discussed in this handout so we will concentrate on anti-seizure drugs specifically. A variety of treatments are available, the treatment chosen will depend on each individual case. Several changes of dose rate, timing and drug may be required before the regime that suits your cat best is found. This can be a frustrating time but the benefits of finding the right treatment become self evident. Even with treatment it may not be possible to completely prevent fitting, in many cases the aim is to reduce frequency and severity of seizures so your cat can lead a more normal life.

Golden rules of treatment

• ALWAYS follow the instructions on the label. Both the dose rate and timing of the medication is important to maintain adequate drug levels in the bloodstream.
• NEVER run out of the medication as sudden withdrawal of treatment can lead to serious fitting.
• LET your vet know when your supply is running low so a repeat prescription can be arranged. This is particularly important if the treatment needs to be ordered specially for your cat.
• KEEP these drugs safe and out of reach of children and animals as accidental ingestion can be life threatening as they are powerful sedatives.
• BE CAREFUL about other drugs including herbal remedies that you also give your cat as they can interfere with these medications making the levels of the drugs too high or too low.  If in doubt check with the veterinary practice.

What are the side effects of treatment?

Mild side effects are common particularly at the beginning of treatment or following dose changes. The most common side effect is sedation but other signs can also occur, most disappear quite rapidly as the cat becomes used to the medication. If side effects persist or seem severe then the veterinary practice should be informed. It is important to remember that in the first 1-2 weeks the side effects of the medication are at their worst and the benefits are at their least. Try not to be disheartened by this as the long-term benefits often outweigh the side effects. As sedation is a common side effect of many of these medications it is important to keep your cat safe from harm. This may mean keeping your cat indoors for the first few weeks so it can be observed and medicated easily and safe from other animals and cars. Cats may become clumsy so it is important to keep them from places they can fall from (stairs) or into (pools or ponds). 

DO NOT BE TEMPTED TO CHANGE THE DOSE OR TIMING OF MEDICATION WITHOUT CONSULTING YOUR VETERINARIAN FIRST

Why has treatment failed?

Sometimes treatment will appear to have failed, in many cases this is because the dosage and timing of the medication is not yet right. Please check that you are following the instructions on the medication label correctly. In some cases your veterinarian may want to take a blood sample to ensure that your cat has the correct blood levels of the medication.

Other causes of treatment failure include:-

1. Failure to recognise and treat an underlying disease

2.  Progression of disease.

3.  Some cases are uncontrollable even with medication.

Seizures are a dramatic event and seeing your cat seizure is often upsetting. It is important to remember that as long as the seizure is short lived and the cat does not come to harm during it (fall or drown) they are not life threatening and your cat is unlikely to remember the event.  With idiopathic epilepsy many cats can be maintained on simple medication that makes their quality of life quite normal.