For a cat or dog owner, there is almost nothing as terrifying as watching your beloved pet have a seizure. Luckily, most pets recover well spontaneously, allowing time for diagnostic tests and therapy where required. A seizure is a loss or derangement of consciousness. A ‘classic’ or ‘grand mal seizure’ involves loss of consciousness with jerking or convulsing of the body. ‘Focal’ seizures may involve repetitive whisker twitching, facial jerks or abnormal limb posturing. Behaviours such as fly chasing or tail chasing, although just a quirk in some pets, can also indicate an underlying disorder.
Seizures have many potential causes and even after initial tests, your vet may not be able to tell you what caused your pet’s symptoms. Vets classify the underlying causes as extracranial (from outside the brain), or intracranial (from within the brain). Causes of extracranial seizures can be further divided into those from the body (e.g. liver failure, low blood sugar) and those that arise externally (e.g. toxins, overheating). Intracranial causes of seizures include progressive disease (e.g. cancer or infection) and non-progressive disease such as epilepsy, where the symptoms may progress but the underlying disease does not.
A pet presenting in ‘status epilepticus’, who has constant seizures, requires intensive emergency care prior to diagnostic testing. Your vet will want to know your pet’s history, especially if there has been exposure to toxins such as snail pellets, other organophosphates (pesticides), caffeine, chocolate etc. Any other change in their health might also give clues as to the origin of the seizure.
Initial blood and urine tests will look for organ disease, abnormal glucose levels and sometimes tests for specific infectious diseases. Where no abnormality is found, more invasive tests can be done. A cerebrospinal fluid (CSF) tap is a sample of the fluid that bathes the brain, and is done under general anaesthetic. It is not without risk, and is generally only done when a diagnosis of progressive intracranial disease is suspected. Advanced imaging includes computerised tomography (CT) or magnetic resonance imaging (MRI) scans which may show abnormality in the structure of the brain.
Treatment of a seizure depends on the cause. If the diagnosis points to an extracranial cause such as liver disease or low blood sugar, the focus will be on treating the disease in order to improve the seizures. Seizure control therapy might include drugs such as diazepam (Valium), phenobarbitone and potassium bromide. Drugs such as corticosteroids and antibiotics might be used for specific intracranial diseases.
Prognosis depends largely on the cause of the seizure. A dog with stable, infrequent epilepsy may not even need medication. On the other hand, a pet with a brain tumour might need lifelong veterinary care. In many cases, the decision to treat is made by the owners based on the frequency and severity of the seizures. A dog with a brain tumour and a poor prognosis will, in most cases, have palliative treatment. However even dogs can have brain surgery for tumours (where the facilities and surgical and critical care expertise allow)!