Seizures in Cats
A seizure occurs when there is a sudden change in the brain’s electrical activity, which manifests in various ways. Seizures are often characterized as generalized or partial, depending on the clinical signs exhibited by a cat. Generalized seizures, commonly referred to as grand mal seizures, can involve a combination of rigidity, leg paddling, convulsions, mouth-chomping, salivating, loss of consciousness, and loss of urinary and/or bowel control. To the untrained eye, partial seizures may be harder to recognize, and can include episodes of aggression, biting, tail chasing, or shadow chasing.
Seizures tend to last only a minute or two, with many owners not even realizing their cat has suffered from one. However, things such as abnormal behavior or a puddle of urine or feces in the house may give them a clue that something is wrong.
The Four Periods of Seizures
Seizures and the time around them can be grouped into four periods:
- Preictal period: This is the time just before the onset of a seizure when changes begin to manifest in the brain. Some cats will exhibit constant head turning or various behavioral changes, such as anxiety or neediness.
- Ictal period: This is the actual seizure itself.
- Postictal period: This is the time just after the seizure, during which the cat begins to recover. During this period, a cat may exhibit sleepiness, pacing, depression, excitement, or an increase in thirst or hunger. These changes often subside within 1 – 2 hours, but have been reported to last as long as 24 – 48 hours.
- Interictal period: This is the time in-between seizure episodes, during which a cat has fully recovered. It is during this period when your veterinarian or a veterinary neurologist should perform a full neurologic examination on your cat, since it is less likely that any preictal or postictal changes will affect their results.
Causes of Seizures
Causes of seizures can be divided between intracranial causes (inside the brain) and extracranial causes (outside of the brain):
- Intracranial Causes
- Infections, including parasites like toxoplasmosis
- Malformation of the brain and its associated structures
- Extracranial Causes
- Systemic disease, such as that affecting the liver or kidneys
- Low blood sugar (hypoglycemia)
- Various toxins
- Infections, including parasites
- High blood pressure (hypertension)
- Low blood oxygen level (hypoxia)
- Electrolyte abnormalities
A full diagnostic workup with your veterinarian and a veterinary neurologist is necessary to eliminate all potential intracranial and extracranial causes. If all appropriate diagnostics are performed and no significant findings are noted, your cat may be diagnosed with idiopathic epilepsy, which means that there is no identifiable cause. Most cats with idiopathic epilepsy present with their first seizure between the ages of 1 and 5 years, but it should be noted that idiopathic epilepsy is much more common in dogs than in cats.
Diagnosis of Seizures
In order to evaluate for a potential underlying cause, a full systemic and neurologic workup is necessary. Most owners will start this at their regular veterinarian, where their cat’s blood pressure, blood values, and urine will be checked. Infectious disease screenings may also be performed. If all of those tests come back normal, your vet will likely refer you to a veterinary neurologist for more advanced testing, such as imaging of the brain using magnetic resonance imaging (MRI) or testing of the cerebrospinal fluid (CSF tap). A diagnosis of idiopathic epilepsy can only be made if all tests are performed and come back normal.
Treatment involves addressing the underlying cause of the seizures and managing the seizures themselves. For instance, if a cat is suffering from a brain tumor, surgery may be indicated. If a cat has contracted a parasitic infection, they will need to be treated with the appropriate medications. If there is an underlying systemic disease (such as high blood pressure), that will need to be managed.
For cats with idiopathic epilepsy, and even some cats with an identified underlying cause, seizures may need to be managed with long-term anticonvulsants (antiseizure medications). Your veterinarian may decide to initiate such treatment if your cat is suffering from episodes more frequently than every 6 – 8 weeks. The goal of anticonvulsant therapy is to help reduce the severity and frequency of the seizures and improve the overall quality of life of the patient. Anticonvulsants may be added or adjusted in order to obtain adequate seizure control, but it is important to remember that every patient is unique and adequate control for one patient may not necessarily be adequate for another. Ideally, 1 – 2 months seizure free when on medication is considered adequate, but some cats are unable to achieve this level of control, while others can go much longer in-between seizures.
The most commonly used first-line anticonvulsant in cats is phenobarbital. Common side effects of this drug include sedation and trouble walking after its initiation or dose changes, which typically resolve within 1 – 4 weeks. It can also cause an increase in thirst, urination, hunger, and consequential weight gain. More serious side effects can include liver toxicity, but this does not appear to be as prominent in feline patients as it is for dogs. Other drugs your veterinarian may prescribe include levetiracetam and gabapentin. Like cats on other long-term medications, cats on anticonvulsants will require regular visits to the veterinarian for routine blood work. You should consult your veterinarian to discuss the best medication option for your cat.
What Constitutes an Emergency?
A cat who has suffered an isolated seizure usually does not need to be seen at an emergency hospital. An isolated seizure is described as one episode occurring in a 24-hour period that does not last longer than 5 minutes. However, these cats should be evaluated by a primary care veterinarian to discuss diagnostic and treatment options.
A cat suffering from cluster seizures or status epilepticus does warrant a visit to the emergency hospital. Cluster seizures are when a cat has more than 2 seizures in a 24-hour period that are separated by a normal interictal period. Status epilepticus occurs when a seizure goes on for longer than 5 minutes or a patient has multiple episodes within a 30 minute period without full recovery in between.
If you feel your cat’s seizures warrant an emergency visit, you should always be careful picking them up and should use a towel to avoid any scratches or bites. You should transport them in a carrier to prevent them from injuring themselves or others.
How You Can Help
Has your cat had a seizure? The best thing you can do is take a video of the episode. This will help your veterinarian immensely in determining whether or not your cat has had a true seizure, since other disorders can present similarly, such as fainting or vertigo.
Does your cat already have a history of seizures? If so, it is important to keep a journal noting the time, date, and characterization of each episode. This will help your veterinarian determine if adjustments or additions to your cat’s medication regimen are warranted.
If your cat is already being managed with anticonvulsants, you should never change the dose or stop the medication without consulting your veterinarian, as this can lead to serious side effects.
For specific questions or concerns regarding seizures in your cat, speak with your veterinarian.