A seizure is the result of sudden and abnormal neurological activity, basically a kind of electrical storm in the brain. In humans and dogs, seizures can manifest themselves in many ways and have a multitude of causes. However, seizures are always accompanied by altered or loss of consciousness. They may last a few seconds, several minutes, or, in the worst cases, hours. In general, seizures in dogs can be categorized into two categories: generalized and focal.
Generalized Seizures in Dogs
These seizures are sometimes referred to as "grand mal," though this term is used less commonly in veterinary medicine than in human medicine. Generalized seizures visibly affect the entire body and are characterized by overall stiffness and/or spastic, involuntary movements. During this type of seizure, the dog typically experiences full-body rigidity along with convulsions. The dog may lose control of its bladder and/or bowels. Some dogs will vocalize. Also called "tonic/clonic" seizures, generalized seizures are the most common type of seizures seen in dogs.
Focal Seizures in Dogs
Sometimes called partial seizures, these are isolated to a particular part of the brain and therefore affect a specific part of the body. Focal seizures are typically quite mild and may simply be characterized by facial twitching. However, they can occur in another part of the body, such as a limb.
Sometimes, a focal seizure will look like a fainting spell or a brief period of disorientation. In other cases, a dog experiencing this type of seizure may compulsively snap at the air (sometimes called "fly biting").
Cluster Seizures in Dogs
If your dog has more than one seizure in a 24 hour period, then they are considered cluster seizures.
Dogs that experience these types of seizures have a more urgent need for medical treatment than dogs with occasional seizures. Additionally, if your dog has more than three seizures in a 24 hour period, it is considered an emergency. Your dog should be seen by your primary care veterinarian or an emergency veterinarian that day. Delaying may result in increasing frequency and severity of the seizures, posing a greater threat to your dog's health.
Canine Status Epilepticus
Status epilepticus is a prolonged seizure or a series of seizures that occur continuously. This is a dire emergency situation that, if untreated, can lead to brain damage, hyperthermia (elevated body temperature) and even death. Dogs in status epilepticus require hospitalization and often need to be placed on a drip of Valium (diazepam) or another drug to stop the seizures.
Phases of a Dog Seizure
Many seizures are preceded by a period of abnormal behavior called the pre-ictal phase. During this stage, dogs often exhibit signs of anxiety and apprehension.
They may whine, pace, and/or pant. Not all dogs display pre-ictal signs, and some may only do so intermittently.
The seizure itself is sometimes referred to as ictus or the ictal phase.
Following nearly every seizure is the post-ictal phase. This period may last minutes to hours and is often characterized by stupor, disorientation and/or blindness. The post-ictal phase can vary with each seizure. This phase should not be confused with the seizure itself.
Causes of Seizures in Dogs
Seizures occur for a number of reasons. In an attempt to find a cause, your vet will recommend a variety of diagnostic tests. This typically starts with blood tests but may lead to advanced brain testing such as CT, MRI, and cerebrospinal fluid (CSF) tap. In the case of the latter, your vet might refer you to a veterinary neurologist. The following disorders may be the source of seizures in a dog:
- Structural or developmental abnormality
- Reaction to toxin or allergen
- Systemic disorder, such as liver shunt or thyroid disease
- Bacterial or viral infection
- Brain tumor (malignant or benign)
- Idiopathic Epilepsy
Canine Idiopathic Epilepsy
Epilepsy is an idiopathic disease, meaning its cause is unknown. There is no specific test to diagnose epilepsy, so advanced diagnostic tests (CT, MRI, spinal tap) are recommended in order to rule out other causes for the seizures. However, a presumptive diagnosis is sometimes made when a dog fits the criteria for epilepsy. Typical onset of epilepsy is between the ages of one to five years. Breed and family history may also play a role. Though uncommon, dogs outside of this age range may still be epileptic. Many epileptic dogs will respond quite well to drug therapy, but they usually must be on medications for life.
If you suspect that your dog is having a seizure, do not panic. However, there are some steps to take.