Canine Epilepsy
Canine epilepsy is a seizural disorder, categorized as either acquired or idiopathic. Acquired epilepsy has a known cause, usually a head injury or a brain tumor. Idiopathic epilepsy, on the other hand, has no known cause, although it appears to be genetic. It is postulated that it may be the result of a chemical imbalance in the brain that interferes with the transmission of electrical impulses. Canine epilepsy causes the affected dog to have sudden spells of uncontrolled movements that may or may not result in a loss of consciousness. Left untreated, canine epilepsy results in increasingly frequent and more severe seizures.
Risk Factors for Canine Epilepsy
Idiopathic canine epilepsy is found more frequently in male dogs. Certain breeds are genetically predisposed to developing the condition, but mixed breeds can also suffer the disorder. Breeds in which epilepsy occurs more frequently include:
- Beagle, dachshund, wire-haired fox terrier
- Golden retriever, Labrador retriever, poodle
- German shepherd, St. Bernard, Bernese mountain dog
- Siberian husky, Keeshond, Irish wolfhound
- Cocker spaniel, collie, Shetland sheepdog
Inheritance has only been scientifically substantiated in some of these breeds, but dogs in all of them are at increased risk of developing the disorder.
Symptoms of Canine Epilepsy
Typically, the onset of this disorder occurs in dogs between 10 months and 3 years of age, though initial grand mal seizures have been reported in puppies as young as 6 months and in dogs as old as 5 years. Seizures basically have three stages: the aura, the grand mal seizure and the post-seizural period.
The Aura
During the hours before a seizure, the dog may be restless. One or more of the following symptoms may be observed:
- Whining
- Excessive salivation
- Unusual affection
- Wandering or hiding
- Hysterical running
- Anxiety or apprehension
The Grand Mal Seizure
During the seizure, which may last for 1 to 3 minutes, the dog will fall on its side, convulsing, its muscles tight. Other symptoms of a grand mal seizure may include:
- Chomping the jaw
- Drooling
- Urination
- Defecation
- Vocalization
- Moving all four limbs simultaneously
At times, a canine seizure does not manifest typical grand mal symptoms. In such cases, the dog may bark furiously for no apparent reason, lick or chew itself in a frenzy, stare into space, or snap at unseen objects.
The Post-Seizural State
This period may last for minutes, hours or days after a canine seizure. During this time, the dog is conscious, but clearly not fully functional and may exhibit the following symptoms:
- Confusion
- Disorientation
- Increased hunger or thirst
- Compulsive behavior
- Lack of responsiveness
- Wandering or restlessness
- Transient blindness
Seizures may occur in clusters during 1 to 4 week periods, especially in large breeds. Most frequently the seizures occur while the animal is at rest, during the night or early morning. It is entirely possible that the dog will not be observed in all three stages of epilepsy.
Diagnosis of Canine Epilepsy
In order to diagnose canine epilepsy, the veterinarian will request a log of the frequency of seizural activity and about the dog's observed behavior before, during and after an attack. Usually, epileptic seizures become more frequent with time. Tests administered to make a definitive diagnosis of canine epilepsy include:
- Electroencephalogram (EEG)
- Spinal tap to analyze cerebrospinal fluid
- X-rays of the skull
- CT or MRI scan
The X-rays and scans check for brain lesions or tumors. The EEG measures electrical impulses in the brain. The spinal tap is taken so that cerebrospinal fluid can be analyzed.
Treatment of Canine Epilepsy
While there is no cure for canine epilepsy, symptoms can be successfully diminished with anticonvulsants. Treatment, given on an outpatient basis, is usually started if the animal has two or more seizures per month. The goal is to decrease the number of seizures and their severity. The most commonly used medication is Phenobarbital, sometimes combined with potassium bromide. Phenobarbital is the more effective treatment for most dogs, but it has the side effect of being sedating and may possibly cause liver damage with long-term use.
Weight gain is side effect of anticonvulsant medications, so dogs with canine epilepsy should have their weight monitored. If they are being treated with potassium bromide, they should not be given anything salty as this may precipitate seizural activity. In addition, dogs with canine epilepsy should be kept from swimming to prevent accidental drowning. During treatment for canine epilepsy, dogs should have blood work done regularly.