Seizures in Dogs
When it comes to seizures in dogs, there are a number of types of seizures, and how these different types affect individual dogs can also be very different. Although there are different categorizations, it is certainly not unusual for an individual dog to experience more than one type of seizure, and not all seizures necessarily involve convulsions.
Seizures in dogs can happen suddenly, without warning, and last just a short period of time (a few seconds to a couple of minutes).
Although injuries resulting from seizures in dogs can happen, they are rare. Most dogs having a seizure do not hurt themselves and often do not require a trip to the vet. That said it is important to contact your vet if your dog has had a short seizure just to let them know what has happened, and seizures lasting longer than about 3 minutes require immediate veterinary attention.
What Causes Seizures in Dogs?
There are two types of seizure causes, extracranial and intracranial.
Extracranial causes of seizures originate elsewhere in the body but are still able to affect the dog's brain and cause seizure activity. The most common extracranial causes are hypoglycemia, hypocalcemia, hyperthermia, hypothyroidism, liver disease, or ingested poisons such as caffeine, chocolate.
Intracranial causes of seizures are diseases that cause either structural or functional changes inside the dog's brain. The most common intracranial causes are genetic epilepsy, trauma to the brain, tumours, nutritional imbalances, autoimmune disease, or infectious diseases such as canine distemper virus (CDV) and rabies.
Types of Seizures
Seizures can be divide into two major grouping of focal seizures and generalized seizures. These two categories can be further subdivide. Below is an overview of what each category of seizure.
Focal Seizures (Partial Seizures)
Focal, or Partial Seizures only affect one half of your dog's brain and within a particular region of that half. This type of seizure will be explained as simple or complex, based on your dog’s level of awareness when the seizure occurs. Dog's typically remain conscious during a simple focal seizure, although consciousness is likely to be more impaired during a complex focal seizure.
Signs of a Simple Focal Seizure
Dogs experiencing a simple focal seizure can show a wide variety of symptoms such as:
- Fur standing up
- Dilated pupils
- Growling, barking, or moaning
- Involuntary movements
- Specific muscles may contract and relax
- Signs of vision or hearing changes
- Balance problems
- Hallucinations (Your dog may bark or growl at nothing, bite at the air or behave fearfully for no apparent reason)
Generalized Seizures
Generalized seizures occur within both sides of your dog's brain and may begin as a focal seizure then evolve into a generalized seizure. Typically dog's that are experiencing a generalized seizure will lose consciousness (urination and defecation can occur).
Types of Generalized Seizures in Dogs & Their Symptoms
These seizures are characterized by movement on both sides of the body and fall into 5 categories:
- Tonic: Muscle contraction or stiffening that can last from seconds to minutes
- Clonic: Involuntary rapid and rhythmic jerking or muscle contractions
- Tonic-Clonic: Tonic phase followed immediately by a clonic phase
- Myoclonic: Sporadic jerks or movements typically on both sides of the body
- Atonic (drop attacks, non-convulsive seizures): A sudden loss of muscle tone which causes the dog to collapse
- Cluster: Two or more seizures within a 24-hour period with the dog regaining full consciousness between seizures
- Status Epilepticus: Either (a) a single seizure lasting longer than 5 minutes, or (b) a number of seizures over a short period of time without regaining full consciousness between each seizure. If your dog suffers from a Status Epilepticus seizure call your vet immediately for advice. Seizures lasting longer than 5 minutes can be life threatening.
Focal Seizure Evolving Into a Generalized Seizure
A focal seizure that goes on to evolve into a generalized seizure is the most common seizure type seen in dogs. Often times the focal seizure is so short or subtle that the signs can be missed by even the most attentive pet parents. If your dog begins having a generalised seizure, try to remember exactly what your dog was doing before it began, and let your vet know when you speak to them. A full understanding of what your dog was doing before the generalized seizure began can help your vet to diagnose the type of seizure your dog is experiencing and possible cause.
Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.