EPILEPTIC SEIZURES; CAUSE & TREATMENT
Barbara J. Andrews, TheDogPlace.org Publisher
Epileptic seizures may be inherited or acquired but are increasing proportionate to increased use of vaccines and
What precipitates a seizure, how to recognize onset, types of seizure, traditional and alternative epilepsy treatment and prevention.
Seizures, often called convulsions, are a neurological malfunction; an uncoordinated firing of neurons in the brain due to injury, hereditary factors, toxins, metabolic or electrolyte imbalances.
Types of epilepsy are primary and secondary. Primary or idiopathic epilepsy is considered genetic, i.e. true inherited epilepsy, an inherited biochemical defect of neurons leading to abnormal electrical brain activity. Diagnosis can only be based on pedigree knowledge and whether the condition exists in statistically significant numbers of close relatives. Secondary or acquired epilepsy is believed related to a cause; i.e. injury or disease.
Types of seizures are divided into generalized (Grand Mal, mild, or petite), cluster, and status epilipticus. Generalized seizures are dramatic and thankfully short in duration, usually lasting less than a minute during which time the dog looses consciousness, becomes rigid, the legs paddle, the body may become rigid, breathing may stop (clearing throat and quick careful rib cage depression may jumpstart), pupils dilate, and the dog may urinate or defecate. Petite Mal or partial seizures may be brief, hardly noticeable, or dramatic. Examples are a few seconds of lost consciousness or disorientation, staring, upward rotation of eyes, twitching, or in complex partial seizures, chewing, licking, whining or barking, bizarre behavior such as snapping at imaginary flies, cowering or hiding, or pacing in circles.
Cluster seizures are characterized by two or more seizures within a few minutes or hours but with the patient regaining consciousness between the seizures. A single seizure or even a cluster seizure of short duration is rarely life-threatening but frequent seizures may lead to status epilepticus.
Status epilepticus is defined as one continuous seizure lasting several minutes or two or more individual seizures without full recovery of consciousness between seizures. This is a medical emergency requiring prompt treatment since continuous seizure activity lasting over 30 minutes can cause life-threatening abnormalities and brain damage.
Treatment for seizures in dogs are similar to those for humans. While treating the seizure treats the disease, seizures must be regarded as just one symptom of a disease process. There may no definitive diagnosis in dogs as neurological tests can be prohibitively expensive. The goal however, is to determine whether the seizures are due to idiopathic (inherited) epilepsy or represents some form of active disease. It is the latter which requires the most effort to diagnose, eliminate, and restore normal brain activity. Whether single, cluster or status epilpticus seizures, the treatment objective is to quickly stop the seizure, provide support for the dog, control frequency and/or prevent future seizures. This initially involves immediate veterinary care to administer anti-seizure medication. When the dog has recovered and patient information has been established, the veterinarian may dispense one of the following:
Diazepam (Valium) for at-home rectal administration by the owner. Diazepam is a safe treatment for cluster seizures in dogs with idiopathic epilepsy and is usually the treatment of choice for emergency treatment of seizures because it is safe, takes effect quickly, and is effective against many types of seizures. Although vets may inject diazepam by vein, most owners are not able to so and giving it by mouth is extremely difficult when the dog is actively seizing. Diazepam inserted rectally offers safer, better results and is ideal for home treatment of cluster seizures.
Phenobarbital is an inexpensive and effective preventative. Many vets feel it is better to start at a higher maintenance dose and then reduce dosage to achieve a steady blood level. Possible toxicity can be assessed by tests and adjust with dosage.
Phenobarbital is immediately effective but requires a few days to achieve the steroid-like effect and to determine whether the sedation effect is too strong in that dog. The sedation effect will usually decrease within a couple of weeks as the dog develops tolerance to the medication. Phenobarbital seems to act through increasing GABA neuron activity, an inhibitory neurotransmitter in the central nervous system. Most neurologists feel that 80% of all seizure disorders can be controlled by Phenobarbital.
Potassium bromide (KBr) is another effective anticonvulsant which has recently been re-discovered. KBr is usually used along with phenobarbital therapy that fails to completely control seizures. KBr is believed to control 75% of seizures that can’t be prevented with phenobarbital alone. It must be made by a compounding pharmacist who can dispense in capsules or liquid form.
There are other medications which your vet may discuss, bearing in mind all drugs have some side effects. Your vet may also suggest acupuncture, ocular pressure to stop or reduce seizure severity, and nutritional support such as vitamin B6, magnesium, and manganese but these are supportive therapies used in conjunction with medication.
Ocular Pressure is something you can try. It is not a veterinary-recommended procedure but there has been some informal testing. At the first definitive sign of imminent seizure, gently apply pressure to the closed eyelids for 10 to 20 seconds and release, noting whether twitching, spasmodic trembling or jerking subsides. Ocular pressure is believed to release a calming chemical, almost like administering valium. The response can be quite dramatic or it may prove ineffective. Release for an equal time while talking calmly and soothing the dog. If the dog is having a Grand Mal seizure use extreme caution as you could damage the eyes or get bitten unless you have someone to help hold the dog. Repeat up to 5 or 6 times until dog is completely relaxed and can be transported to the veterinarian.
Seizure Indications and stages. There is a period during which the dog may sense that a seizure is immanent. Some dogs will show signs an observant owner will learn to recognize but on occasion, there is be no warning at all. Seizures more often occur in early morning or late evening. Rage Syndrome, in which a normally gentle dog attacks the closest object or person, has been reported as most often occurring when the dog awakes from a deep sleep.
Seizures are divided into the ictus (the actual seizure event), the post-ictal phase (during which the dog may be agitated, pace restlessly, seem hungry, or fall into an exhausted sleep) and the inter-ictal phase (the time between seizures which may be days or months during which the animal appears perfectly normal).
Age of Onset. Idiopathic (genetic) epilepsy generally shows up between one and three years of age and is most common (or most diagnosed) in purebred dogs and cats. Acquired epilepsy can occur at any age but it may be hard to pinpoint a causative injury that occurred six months to a year earlier. Because of the delay factor following injury, acquired epilepsy is rarely seen before a year of age unless there is a known relationship to administration of rabies vaccine.
Rabies vaccine induced seizures are so common that there are 51,000 online references to the connection between rabies vaccine and seizures. Significantly, none are veterinary university or vaccine manufacturer sites. Breeder should not be in denial about the hereditary aspect of epilepsy but “acquired/injury” definitely include rabies vaccine reaction and the potential as a causative factor in subsequent seizures. Rabies is a viral infection that attacks the central nervous system. Symptoms of rabies infection include seizure. (Psuedorabies, a highly contagious, usually fatal disease can affect many species but is unrelated to rabies.)
Because active seizures (as opposed to an isolated incidence) signifies systemic disease, such seizures tend to occur with greater frequency in diseased animals and when the immune system is overburdened or becomes less active with advancing age. Active seizure disease is most common prior to a year of age when growth stress and vaccine challenges occur or after six years of age when the immune system begins to weaken.
Inherited or Acquired Seizures? Determining inherited epilepsy is complex. When genetic, it appears to involve six gene pairs, thus it is more complicated than hip dysplasia. If breeders note greater than 6% in their bloodline, they should investigate environmental factors but if nothing can be detected, they must consider it hereditary. Statistics show that colony-bred beagles have an incidence of 5.9%, based upon random breeding selection and matings so a higher percentage in a breeding program indicates more than chance occurrences of seizures.
Diagnosing the cause of seizures may include urinalysis, CBC, Chemistry Profile plus serum cholinesterase and serum bile acid concentrations, heartworm and internal parasite tests, plus chest and abdominal radiographs if there are any suspicious findings and in dogs over six years of age. If such tests reveal no cause related to epilepsy, the vet and patient should consider diagnostic tests such as spinal tap, EEG and MRI examinations.
There is concern that every time a dog has a seizure, the central nervous system pathway becomes more established and increases odds of subsequent seizures. This suggests that early intervention and prevention aids ultimate control of seizures but some professionals believe anticonvulsants should not be used until the seizure frequency is such that a determination can be made re whether the anticonvulsant is working. Everyone agrees that treatment should be started in cases of severe seizures or when there is a cluster pattern with multiple seizures.
Environmental and nutritional factors such as Heartgard or Heartgard Plus, Program and Advantage appear to lower the seizure threshold and make seizure disorders more difficult to control. Exposure to organophosphate insecticides should be limited. Interceptor and Filaribits appear to be safe for epileptic dogs. Of the newer flea control products, Frontline (Top Spot) appears to be safe for dogs with seizure disorders.
Dr. Jean Dodds, well known veterinarian and researcher, suggests that hypothyroidism may be a contributing factor to seizures and neurologic manifestations, listing seizure as one clinical sign of hypothyroidism.
Don’t hesitate to search for human epilepsy and seizures as in this case, advances will be more rapid due to the human ability to verbalize symptoms, onset of seizure, etc. Interestingly, dogs are able to recognize when a seizure is imminent in their owners, just one more amazing ability for which service dogs are trained.
Canine Epilepsy Resource Center - www.canine-epilepsy.com - the first all breed canine epilepsy list.