A Brief Overview of Canine Epilepsy
Written by Marion Mitchell
Seizures are the result of muscle responses to an abnormal nerve-signal burst from the brain. They are a symptom of an underlying neurological dysfunction. Toxic substances, metabolic or electrolyte abnormalities and/or imbalances cause an uncoordinated firing of neurons in the cerebrum of the brain, creating seizures from mild "petit mal " to severe "grand mal".
There are four basic stages to a seizure:
- The Prodome: may precede the seizure by hours or days. It is characterized by changes in mood or behavior.
- The Aura: signals the start of a seizure. Nervousness, whining, trembling, salivation, affection, wandering, restlessness, hiding and apprehension are all signals.
- The Ictus, the actual seizure:. A period of intense physical activity usually lasting 45 seconds to 3 minutes. The dog may lose consciousness and fall to the ground. There may be teeth gnashing, frantic thrashing of limbs, excessive drooling, vocalizing, paddling of feet, uncontrollable urination and defecation.
- The Post Ictus/Ictal: after the seizure, the dog may pace endlessly, appear blind and deaf and eat or drink excessively.
The Cause: anything that disrupts normal brain circuitry:
- Idiopathic Epilepsy: meaning no known cause and possibly inherited. This is also referred to as Primary Epilepsy. Check history of pedigree and make sure your veterinarian has looked for possible underlying factors.
- Seizures caused by underlying factors are referred to as Secondary Epilepsy. The following tests are advised before a diagnosis of idiopathic/inherited epilepsy is made.
- Glucose tolerance test, to check for hypoglycemia.
- Thyroid panel, 6 tests, to check for low thyroid function/hypothyroidism.
- EEG, to see if there are findings suggestive of a lesion (an abnormal EEG is standard with epilepsy, but a vet or a physician will also be able to tell if there is a lesion.
- Cerebrospinal fluid analysis, to look for encephalitis, distemper and other infection.
- Blood test to check for lead poisoning;
- CT scan or MRI, again to look for a brain lesion
Types of Seizures:
- Mild: (Petit Mal) this can be a simple as momentarily staring into space, or upward eye movement.
- Moderate: (Grand Mal) the dog falls down, loses consciousness and extends its limbs rigidly. Paddling of limbs, salivation followed by possible loss of control of bladder and bowels and vocalization (blood curdling scream) may follow. This may occur for 1-3 minutes and is most often followed by a period of restlessness, pacing, bumping into objects and loss of balance. (Post Ictal period) The dog is conscious but may appear deaf, blind and disoriented. Great care must be taken to prevent the dog from injuring itself at this time. The use of Bachs Flower Essence Rescue Remedy (found in any Health Food Store) has been found to be extremely useful when given at this time. Simply put a 4 drops of the Essence into the dog's mouth after the seizure has finished. In most dogs the post ictal time will be cut considerably.
- Status Epilepticus: Status can occur as one continuous seizure lasting 10 minutes or more, or a series of multiple seizures in a short time with no period of normal consciousness, this may be life threatening.
- Cluster Seizures: Multiple seizures within a 24-hour period time, may also be life threatening. It is often difficult to distinguish between the two types and veterinarian assistance is imperative. Rectal Valium is extremely useful in breaking cluster seizures.
- Potassium Bromide
- Phenobarbital & Potassium Bromide
- Primidone (Mysoline)
- Valium (Diazepam)
- Keppra (Levetiracetam)
Most dogs can be controlled by using Phenobarbital and/or Phenobarbital and Potassium Bromide. Potassium Bromide is used alone if the dog's liver has become damaged by Phenobarbital. IMPORTANT: Dogs on Phenobarbital need to have their liver enzymes tested every few months using the following tests ALT (SGPT), AST (SGOT), GGT ALKALINE PHOSPHATASE. Both drugs are available by prescription in pill capsule or liquid form. Primidone, once commonly used, metabolizes to Phenobarbital in the liver. With prolonged treatment it can also cause liver damage. Valium, injectable, or rectal and oral is a good choice to halt a cluster seizure or interrupt status epilepticus. Dilantin, is currently not recommended for use. Gabapentin is a newer drug being used for humans. It does offer exciting possibilities for dogs as it is only partially metabolized by the liver. At present it is very costly to use around $250.00 a month, however with the few dogs that have used it, the results have been very positive.
Keppra (Levetiracetam) was approved by the United States Food and Drug Administration in 1999. The exact mechanism by which levetiracetam exerts its antiseizure effects is not completely understood, although it is a different class of drug from other anti-seizure. It is well tolerated in human patients with minimal side effects. In dogs, levetiracetam is well absorbed after oral administration, is not significantly bound to protein, and is excreted in the urine with minimal liver metabolism. The elimination half-life in dogs is 3.3 hours (compared to 7.7 hours in people). Safety studies in laboratory dogs showed minimal adverse effects even at high doses (UCB Pharma, Inc. Data on file.) NCSU has been conducting extensive trials on Keppra.
Low Thyroid Function - Hypothyroidism & Seizures
Seizures are one of the symptoms of hypothyroidism along with chronic skin disease, hair loss, weight gain, lethargy and slow metabolism, behavioral changes (aggression, hyperactivity, poor concentration, passivity, phobias, anxiety.) A recent study of 634 dogs showed that 77% of the dogs who were hypothyroid also had seizures. Dr William Thomas, a board certified neurologist, had this to say about thyroid testing:
"Thyroid testing should be considered in any dog with recurrent seizures. Such testing is relatively inexpensive and carries little risk to the patient. Any dog that is diagnosed with hypothyroidism by appropriate testing should be treated with thyroid replacement therapy. This applies to all dogs, whether or not they suffer seizures. If the seizures improve with thyroid therapy, then great! If not, the patient should still be treated because hypothyroidism can cause many other health problems. Appropriate use of thyroid medication is one of the safest and effective treatments available in veterinary medicine. " WB Thomas DVM, Dipl.ACVIM (Neurology) University of Tennessee, Knoxville, TN
It is a good idea to have a full thyroid panel of 6 different tests to determine if your dog is hypothyroid. The tests you want to have done are T3, T4, free T3, free T4, T3 and T4 Autoantibodies. Two or three thyroid tests (e.g.T4, free T4 or TSH), are not conclusive for hypothyroidism. You need all 6 tests listed. Proper thyroid medication may reduce or eliminate seizures.
Diet plays an important role in the management of Canine Epilepsy. It is very important to feed a kibble that is preservative free. Preservatives such as Ethoxyquin and BHT, BHA should be avoided as they can cause seizures. Many "Supermarket " foods are loaded with chemical dyes and preservatives, buy a high quality kibble made from "human grade" ingredients or better yet cook for your dog or feed a raw ( BARF) diet. Many recipes can be found in Dr Pitcairn's Complete Guide to Natural Health for Dogs and Cats. Two helpful books on a raw diet are Dr Ian Billinghurst's "The BARF Diet" & Susan Johnson's "Switching to Raw". There is also a good article on the web site called " The Role of a Healthy Diet in the Management of Canine Epilepsy" PLEASE NOTE: If your dog is taking Potassium Bromide be very careful when you switch dog foods. Try to make sure the chloride content is the same as the previous food. Change over very slowly, whether it is the same chloride content or different, so that the absorption rate of the KBr remains constant.
SUSAN WYNN, DVM says: "Dogs evolved from Canis lupis - the wolf. Wolves eat caribou or the like, but if they are forced, they will eat smaller game (rarely). They have been observed to graze on grass, eat berries, etc, but only when they need to. This is our lesson in canine nutrition - they are omnivores who do well with fresh meat, the vegetation they get in a caribou stomach (which is mostly green, unless the beast is eating from baited fields), and a smattering of other stuff if they are hungry.
Food companies have, in the main, revolutionized pet nutrition by eliminating major nutritional deficiencies and providing optimal nutrition for the average pet. Our concern, however, is not for the average pet. It is for the sick pet. If epileptic animals have a disease with even a small nutritional component, wouldn't we want to deal with it? Is your epileptic animal showing other signs of allergies? If s/he is chewing feet, scratching ears, having anal gland problems, vomiting bile seasonally, etc., etc., one may want to consider dietary changes, including hypoallergenic diets, if appropriate.
I think that the main benefit of feeding real food meat, - (raw or cooked, raw or steamed veggies, cooked grains) - is to provide stuff that is killed in the kibble extrusion process. If you or I were to eat a diet of Wheaties, yogurt, VegAll, and Spam day after day for 20 years, would this be enough? I don't know, but it makes me uncomfortable. I think our pets need a more varied diet and a fresher one than we can give them with commercial kibble. So I do recommend supplementing pet food with lean meat and vegetables."
It is important to keep your epileptic dog as free from chemical pollutants as possible. Think about the environment your dog is living in. Do you use chemical sprays on your lawn? Dogs will sometimes seize only when the lawn is sprayed for weeds. How about the cleaner you use for the floor? Some dogs have been known to seize after the floor has been washed with a pine scented cleaner. Flea and tick medications can also cause seizures. It is recommended that epi dogs be given Interceptor as a monthly heartworm preventative and Frontline used for fleas. Avoid products with Ivermectin it has been known to cause seizures in some breeds. There are many things that can lower a dog's seizure threshold. Keep a diary of your dog's seizures. Note down anything you have done or that the dog could have come in contact with that day which could have contributed to seizure. It is also a known phenomenon that some dogs may seizure around the full moon.
Vaccinations can lower a dog's seizure threshold and trigger a seizure. If you feel that this is the case for your dog, ask the vet to split the shots, give them separately at weekly or two weekly intervals and ask for the Rabies shot to be given 2 weeks after that. Ask your vet if he/she knows about the new 3-year protocol now being used by many vets and veterinary schools.
Page last update: 07/30/2011