This workshop discussed the causes, types and management of seizures in dogs. It outlined the processes that need to be carried out when a patient presents to the practice during a seizure
What is a seizure?
A seizure is a clinical manifestation of excessive hyperexcitability in the cerebral cortex. There is a lot of electrical activity going on in the brain and it is not being coordinated in the way it normally is, so the seizure is the clinical manifestation of that electrical activity.
There are two different types of seizure: epileptic seizures, which are essentially a result of intracranial disease, or reactive seizures, the result of a natural response by the brain to some sort of disturbance in the body, such as a toxin or head trauma.
Tonic clonic is a term used to describe a generalised seizure when it happens. The tonicity is the generalised muscle rigidity - the muscles fully contract, the legs go out and they will not bend, they are hypertonic. Clonic refers to rhythmic convulsions or paddling that the patient does. A lot of seizures have these two distinct stages where initially the patient goes really rigid and falls to one side, and then this is followed by the convulsing.
Idiopathic epilepsy is essentially seizures with no underlying structural or metabolic disease, and cluster seizures are multiple seizures that occur over a short period of time.
Types of seizures
Seizures can be focal (sometimes called partial) or generalised. Focal seizures involve just one focal area of the brain, they are much more varied in their presentation depending on the area of the brain that is involved and are not usually associated with the loss of consciousness. Patients might have facial twitches, isolated limb contractions, hypersalivation, behavioural changes, or absence seizures where the patient appears absent.
Generalised seizures involve the entire brain, and these are the ones that present as emergencies in practice. In these, there is a loss of consciousness involving the entire brain, so the patient is unconscious. Sometimes the eyes flicker, but the patient will not respond to commands, will not react if you call their name, and will not be able to get up.
A generalised seizure can cause emptying of the bladder and the bowels, and also breathing abnormalities which can lead to cyanosis in some patients.
Stages of seizures
Prodrome is the period before the onset of the seizure. The patient may exhibit behavioural changes, might be restless, have increased anxiety and abnormal vocalisation. This stage can last hours, even days.
The aura (which can be difficult to differentiate from the prodrome in animals) occurs immediately before the seizure, which is where abnormal electrical activity starts to happen in the brain.
The actual seizure then occurs (discussed in more detail later on), and then the postictal stage, which is the period after the seizure. It is characterized in veterinary medicine by further behavioural abnormalities - the patient might be ataxic, be really wobbly on their feet or may not be able to see, and these abnormalities can persist after the seizure has stopped.
What do you do when a patient arrives at your practice with seizure?
The most important thing is to remain calm, particularly with a seizuring patient. Further stimulation to the patient’s nervous system can cause the seizure to go on longer, so you want a quiet dark room, hushed voices, no sudden movements. If possible, remove the patient from the owner, as owners are often distressed, and monitor the length of the seizure. Administering flow-by oxygen cannot hurt and might help if the patient has been having breathing difficulties. If it is possible to place intravenous access, then that can be helpful, although this might be difficult if the patient is having more violent seizures.
Try and make the patient comfortable - move them away from furniture so they do not hurt themselves, and put a little bed under their head.
What not to do
Do not immobilise the patient, as a severe seizure could cause them to break a limb. Do not try to secure the airway - patients cannot swallow their tongue and there can be a lot of jaw clamping during a seizure which has the potential for the veterinary surgeon or nurse to be bitten.
When the seizure has finished
Be aware of postictal changes. There can be transient neurological deficits - the patient might be unable to see, and that can be really disorientating for them.
Behavioural changes are common as the brain has been over-stimulated. Postictal aggression is quite common and so these patients may try to bite you. It is important to stay calm with the patient in a quiet environment and be a bit careful with them.
The opposite can happen - the patient might be clingy, whingy or whiny. Sometimes they can be very vocal post seizure, so it is important to give them time in a quiet environment for them to come back to normal.
It is now possible to do a total patient review, so check their vitals (including blood glucose and metabolites, to make sure there is not a metabolic cause of the seizure), circulation and cardiovascular status. It is very important to check the patients temperature - the excess muscle activity during a seizure can cause hyperthermia. However, be careful with active cooling post-seizure as once the patient has stopped seizing they can quickly lose this heat.
Seizure plans
Any patient entering the authors hospital that has a known history of seizures or has the potential to seizure will get a seizure plan from the clinician in charge of the case.
This is a predetermined drug and dose that is displayed on the kennel with the drugs easily accessible. Anyone who sees the dog seizuring can just pull up the syringe, draw up the diazepam and administer it straight away.
Seizure plans are really useful for when your vet or the nurse in charge of that patient is not available.
Medications
Antiepileptic drugs are any drugs used to try and stop a seizure. Most of them increase the inhibitory neurotransmitters by acting on the GABA receptors, and so can cause a lot of sedation.
When deciding which antiepileptic drug to use for a particular case, it is important to consider the speed of onset and duration of action, the route of administration and the side effects. You might also chose a different drug for a young dog rather than an old dog. Also consider if there is a need for long-term monitoring on the specific drug, as this has an implication for owners. Further details on specific drugs are beyond the scope of this article, but can be found in Hooper (2021).
Status epilepticus
Status epilepticus is prolonged seizure activity, defined as a single seizure lasting more than 5 minutes. It is a medical emergency and it needs to be treated quickly. This is why it is important to time seizure activity when the dog arrives.
This continuous seizure activity can cause cerebral inflammation and oedema, which predisposes to further seizure activity. It can also cause hypoxia and lactic acidosis.
The nursing care of these patients is important - they may need to be intubated to maintain a patent airway. They need a quiet environment to reduce stimulation, and monitoring of the heart rate, respiratory rate, blood pressure, pulse oximetry and temperature. Nutrition and fluid therapy should be considered, as should recumbency care - the author turns these patients every 4 hours to minimise stimulation. Bladder management and oral and ocular care should also be addressed.
Monitoring for breakthrough seizure activity is important, and a predetermined seizure plan can be particularly helpful for these patients.
Long-term management
Treating seizures can be very frustrating. A patient can be stable on long-term antiepileptic treatment for years and then suddenly start seizuring again.
The aim of antiepileptic treatment is essentially to provide the patient with improved quality of life and this is generally measured as a reduction in the number of seizures, but it is important to have realistic conversations with the clients so that they understand the expected outcome and the level of emotional and financial commitment.
Client compliance is the most important thing with long-term management. The client needs to understand that they need to give these medications two or three times a day for the rest of the patient’s life. They need think about the ongoing financial considerations of this, including paying for blood tests and managing relapses.
For some clients only a seizure-free status might be acceptable. When the nurse says that the aim is to improve the patient’s quality of life, that is a reduction in the number of seizures, but it does not necessarily mean that they will be gone altogether. A lot of seizure patients will still have a seizure, whether that’s every month or two. That might well be acceptable to the client, but they might want a completely seizure-free status and the nurse needs to emphasize that this is not always possible.
It is important to have these conversations with the clients before they start treating this condition. Nurses can play an important part in this - having a handout for the client to take away, and following up with a phone call a couple of days later to check if the client has understood everything and to ask if there is anything else that the client wants to discuss can be really useful and clients really appreciate it.