Seizures in dogs can be a distressing experience for both pets and their owners. While the image of a grand mal seizure, characterized by violent spasms and loss of consciousness, is well-known, seizures manifest in various forms. This article delves into the different types of seizures, their underlying causes, and the available treatment options, drawing upon expert insights from veterinary neurology.
Types of Seizures
Seizures are broadly categorized into generalized and focal seizures, based on the extent of brain involvement.
Generalized Seizures
Generalized seizures, also known as grand mal seizures, involve widespread electrical activity affecting both hemispheres of the brain. The classic presentation includes:
- Tonic-clonic: Sudden collapse, violent jerking of all four limbs (paddling), foaming at the mouth, potential loss of bladder/bowel control, and unconsciousness.
- Tonic: Stiffening and extension of limbs without jerking.
- Clonic: Hyper-flexion and jerking of limbs.
- Myoclonic: Brief jerking of limbs.
- Atonic: Standing, staring, and unresponsiveness.
During a generalized seizure, it’s crucial to ensure the dog’s safety by removing nearby hazards and avoiding contact with their mouth. Post-seizure disorientation can sometimes lead to aggression, so caution is advised. Timing the seizure is vital, as prolonged seizures can lead to a life-threatening condition called status epilepticus, defined as a seizure lasting longer than five minutes. This medical emergency requires immediate veterinary intervention, typically with intravenous medication.
Focal Seizures
Focal seizures originate from a localized area of abnormal electrical activity in the brain. Symptoms can vary widely and may include:
- “Fly-biting” behavior, where the dog appears to snap at imaginary flies.
- “Chewing gum fits,” characterized by repetitive jaw movements.
- Twitching of an eyelid, lip, or ear.
Unlike generalized seizures, focal seizures may not involve a loss of consciousness. While these seizures often do not require treatment, it’s important to monitor the dog closely, as a focal seizure can sometimes progress into a generalized one.
Causes of Seizures
Seizures can stem from a variety of underlying issues, broadly classified as reactive, structural, or idiopathic.
Reactive Seizures
These seizures occur due to temporary or correctable conditions:
- Metabolic disorders: Low blood sugar (hypoglycemia) or low blood calcium (hypocalcemia), liver disease, liver shunts, and kidney disease can trigger seizures. If the metabolic disorder is managed, seizures typically cease.
- Drug-induced seizures: Certain medications can lower the seizure threshold. Discontinuing the offending drug usually resolves these seizures.
- Toxins: Ingestion of substances like dark chocolate, caffeine, xylitol, antifreeze, rat poison, or alcohol can cause seizures. Prompt treatment and removal of the toxin are essential.
Structural Seizures
These seizures result from abnormalities within the brain itself, including:
- Tumors
- Head trauma
- Inflammatory diseases
- Infectious diseases, such as rabies or canine distemper
Idiopathic Epilepsy
Idiopathic epilepsy is a diagnosis of exclusion, meaning it’s considered when all other potential causes have been ruled out. This condition of unknown origin typically appears in dogs between six months and six years of age. Certain breeds, including Schnauzers, Collies, Basset Hounds, Cocker Spaniels, Labrador Retrievers, and Golden Retrievers, have a higher predisposition to epilepsy.
Dogs over six years old experiencing their first seizure are more likely to have a metabolic disorder or a structural brain lesion, such as a tumor or stroke. Puppies under one year are more prone to congenital defects, intoxication, or infectious diseases.
Treatment and Management
The decision to initiate anticonvulsant medication depends on several factors, including the dog’s age, seizure frequency, severity, and breed predisposition.
When to Consider Medication
For dogs between six months and six years old with normal test results, veterinarians generally do not recommend medication after a single seizure. However, exceptions include:
- Cluster seizures: One or more seizures within a 24-hour period.
- Violent seizures.
- Seizures lasting 5 minutes or longer.
- Specific breeds known for difficult seizures: German Shepherds, Border Collies, Irish Setters, Golden Retrievers, Siberian Huskies, Keeshonds, and Saint Bernards.
A seizure log detailing the frequency, duration, and severity of seizures is crucial for determining when to start anticonvulsant therapy. While preventing future seizures is desirable, starting medication unnecessarily can tax the dog’s body and incur ongoing costs. Antiepileptic drugs are typically required for life once initiated.
It’s important to note that even with medication, breakthrough seizures can occur. Furthermore, research suggests that seizures may cause temporary MRI lesions in dogs, similar to humans, which may reverse over time.
A common guideline is to start antiepileptic drugs if a dog experiences more than one seizure per month, as this can significantly impact their quality of life. The ultimate decision rests with the owner, in consultation with their veterinarian.
Medication Options
Common first-choice medications include Phenobarbital, Levetiracetam (Keppra), Zonisamide, and Potassium Bromide. Levetiracetam and Zonisamide are often favored for their efficacy and minimal side effects.
Approximately 20% of dogs have refractory epilepsy, requiring multiple medications. Levetiracetam, particularly its extended-release formulation (Keppra XR), is often used as a second medication, though its short-acting nature necessitates thrice-daily dosing. Managing refractory epilepsy can be challenging, as some dogs may develop a tolerance to their medication over time, requiring higher doses and potentially leading to increased side effects.
Other Therapeutic Approaches
Veterinarians may recommend various additional therapies to help manage seizures:
- Rectal Diazepam or Intranasal Midazolam: These benzodiazepines can be administered at home to shorten or lessen the severity of a seizure.
- Pulse Keppra Therapy: For dogs prone to cluster seizures, a few doses of short-acting Levetiracetam can be given post-seizure to prevent clustering.
- Adjunctive Therapies: Stimulating the vagal nerve by gently pressing on the dog’s closed eyelids for 10-60 seconds may help reduce seizure duration and severity. This maneuver might even prevent a seizure if recognized during the pre-ictal phase.
- Traditional Chinese Veterinary Medicine (TCVM): Acupuncture and herbal remedies can complement conventional treatment, especially for refractory cases, potentially reducing seizure frequency or allowing for lower doses of anticonvulsants. This requires a specialist trained in TCVM.
- Prescription Diets: Purina Pro Plan Veterinary Diet NeuroCare (NC) is a specialized diet containing medium-chain triglycerides (MCTs) that has shown a significant reduction in seizure activity in some epileptic dogs.
Managing seizures in dogs requires a comprehensive approach, involving accurate diagnosis, appropriate treatment, and close collaboration between the owner and veterinarian. By understanding the various facets of this condition, owners can provide the best possible care for their canine companions.
