Canine Epilepsy is a disorder of the brain where abnormal electrical activity triggers further uncoordinated nerve transmission. This uncoordinated and haphazard nerve tissue activity scrambles messages to the muscles of your dog’s body and the use of muscles are then inhibited.
IDIOPATHIC OR SYMPTOMATIC
Because there are many causes of chronic recurrent seizures in dogs, canine epilepsy is not a specific disease or even a single syndrome, but rather a diverse category of disorders. Canine Epilepsy is broadly divided into idiopathic and symptomatic disorders. Idiopathic Epilepsy, or primary epilepsy, means that there is NO identifiable brain abnormality other than the seizures. Symptomatic epilepsy (or secondary epilepsy) is seizures that are the consequence of an identifiable specific cause.
Most dogs with idiopathic epilepsy suffer their first seizure between the ages of one and five years of age. A possible genetic basis for idiopathic epilepsy is suspected in several breeds including those purebreds used in the development of Australian Labradoodle and Labradoodle.
CAUSES OF SEIZURES AND DIAGNOSTICS:
Seizures may be caused by situations within the brain (such as trauma, tumor, or infection) or by situations centered outside the brain (such as low blood sugar, circulating metabolic toxins, hypothyroidism, or external poisons). The first step is to rule out situations centered outside the brain. This is accomplished with blood testing. An ophthalmic exam may also be performed as the retina may show signs of a brain infection. If these tests are negative, the next step is determined by the age of the pet. In my opinion, to date the best testing agency is spearheaded by Dr. Jean Dodd’s and samples can be set by your vet to her organization, hemopet. In my opinion Dr. Dodd’s and UCDavis have the most concentrated resources on the subject. The blog author has no connection with either association.
AFTER BLOOD TESTING, ANIMALS LESS THAN AGE ONE YEAR
Seizures are usually caused by infections of the brain. Analysis of cerebrospinal fluid, obtained by a tap under anesthesia, would be important.
AFTER BLOOD TESTING, ANIMALS BETWEEN AGES 1 AND 5
In these animals, usually no cause can be found and the term “epilepsy,” which simply means “seizure disorder,” is applied. If seizures are occurring frequently enough, medication is used to suppress them. To understand medications ask your vet or go to canine-epilepsy.net and participate in owner forums on the subject.
AFTER BLOOD TESTING, ANIMALS MORE THAN AGE FIVE YEARS
In this group, seizures are usually caused by a tumor growing off the skull and pressing on the brain (a “meningioma”). Most such tumors are operable if found early. ACT scan or MRI would be the next step. For patients where surgery is not an option, corticosteroids may be used to reduce swelling in the brain.
GENETIC OR TUMOR or OTHER CAUSE
Some reasons for seizures are simple and can be eliminated, some are serious. Don’t jump to conclusions, rule out the simple issues first. We had bulldogs who both had seizures (first one then a few months later the second). We changed food from a high protein food to a lesser food and never had another seizure.
Some forms of epilepsy are inherited. Sodium, potassium, and calcium serve the brain as ions and produce electric charges that must fire regularly in order for a steady current to pass from one nerve cell to another. If the channels that carry them are damaged or impaired from birth an imbalance occurs that can cause misfire and seizures.
Both cancerous and non-cancerous brain tumors can cause seizures. Brain tumors are the most common cause of seizures that begin after age 5. Whenever an older dog begins to have seizures, and causes such as toxins, trauma and diabetes have been ruled out, the possibility of a brain tumor should be considered.
Liver disease is a degenerative inflammatory disease that results in the hardening and scarring of liver cells. The liver becomes unable to function properly due to the scarred tissue, which prevents the normal passage of blood through the liver.
Severe worm infestation can result in seizures. Parasites release toxins that have an adverse affect on the central nervous system.
Hypoglycemia or low blood sugar, which brings on feelings of fatigue and stress, may be a factor in triggering seizures. Scientists have estimated that between 50 to 90 percent of all epileptics suffer from low blood sugar, and 70 percent have abnormal glucose tolerance levels.
Toxic metals such as lead, copper, mercury, and aluminum have also been known to cause seizures. Some pets are very sensitive to such metals, and exposure is common through aluminum cookware, auto exhaust, industrial pollution, household cleaners and copper water pipes.
Flea sprays, collars and yard sprays are also toxic to pets. 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.
Because vaccines may contain proteins and/or organisms, they may produce an allergic encephalitis inflammation of the brain. 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. We strongly recommend titers test versus vaccines, always. This is a blood test to determine if acceptable levels of vaccines are present and therefore not necessary. It is amazing how many years most dogs can go without ever needing to be re-vaccinated.
Infections, cysts and cancer can cause seizures.
A blow to the head causing head trauma from an auto accident, abuse or other accident can lead to life-long seizures.
The role of the kidneys is to remove toxins and excess fluid. When the kidneys become diseased or damaged also called Renal Kidney Failure, the kidney may lose the ability to perform, causing a toxic build-up in the body resulting in a seizure. A toxic build-up can lead to a seizure disorder.
Research points to vitamin and mineral deficiencies as possible causes of epilepsy. The key nutrients that appear deficient in epileptics are vitamin B6, vitamin A, folic acid, vitamin D, zinc, taurine, magnesium, and calcium. 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. Dogs should not eat grain.
Genetics (from the Canine Epilepsy Project)
“The Canine Epilepsy Project is a collaborative study into the causes of epilepsy in dogs. It is supported by grants from the AKC Canine Health Foundation (CHF), National Institutes of Health (NIH), individual breed clubs and private donations. Grants supporting this research are CHF Completed Grant #1718, CHF Completed Grant #1729, CHF Completed Grant #1845, CHF Active Grant #2252, CHF Active Grant #2304, and NIH Award #1K08NS0224501.
Their goal is to find the genes responsible for epilepsy in dogs so that wise breeding can decrease the incidence of the disease in dogs. We also hope that knowing what genes regulate epilepsy in dogs may help us better tailor our therapy to the specific cause.
The objectives of their investigations into hereditary canine epilepsy are:
Recruit samples from a large number of affected individuals and their immediate family members (siblings, parents, and grandparents), from many breeds of dogs.
Evaluate the genotype of selected families to search for linkage between DNA markers and clinical epilepsy, and then use this information to identify the causative mutation or mutations.
Devise a DNA marker test that detects and distinguishes normal and mutant (epilepsy-causing) alleles, and make this test available to dog breeders so that they can produce epilepsy-free dogs.
The genes controlling seizure problems in dogs are not well understood. This project is attempting to find the marker(s) or mutation(s) responsible. When these can be identified, a blood test will tell if an individual dog is a carrier, clear, or likely to become an affected (even before symptoms begin). Using this information, breeders can choose breeding partners who will not produce affected puppies.
Breeders and owners often ask what is known about the inheritance of idiopathic epilepsy (also called primary epilepsy or genetic epilepsy). This is an important question because if breeders know the mode of inheritance (that is, the pattern of inheritance across generations), then they may be able to develop breeding strategies that will enable them to breed away from epilepsy. Sometimes, if the mode of inheritance for a disorder is well understood, careful selective breeding can enable breeders to greatly reduce, or even eliminate, the disorder while allowing the breeders to continue with their bloodlines. Of course, when some breeders and owners ask about the inheritance of epilepsy, they are hoping to find evidence that the seizures in their dogs are not due to inherited epilepsy. Sometimes, they do find reason to suggest this. However, many times, they must face the conclusion that inheritance (genetics) was the underlying cause of the seizures.
For readers who are not familiar with the term “mode of inheritance,” we will try to clarify. The mode of inheritance refers to whether the disorder is a simple recessive trait, a simple dominant trait, or a complex trait. Traits that are “simple” are carried by a single gene, while traits that are complex involve more than one gene. With complex genetic traits, the different genes can combine or interact with each other, and the genes can also interact with the dog’s environment. Of course, simple genetic traits are easier to study. The term “recessive” means that a dog will only have the disorder if the defective gene is passed down by both of the parents. Thus, if only one parent passes down the defective gene, the offspring will not be affected with the disorder, although they can be “carriers” and later pass down their one defective gene to their own offspring. The term “dominant” means that the dog can have the disorder even if only one of the parents passes down the defective gene.
As indicated, there currently are no conclusive findings on the mode of inheritance for canine idiopathic epilepsy. However, there are some general theories. Some investigators have theorized that, at least in the breeds they studied, the disorder is likely to be recessive because often two parents that are free of epilepsy produce offspring with epilepsy. Another theory concerns whether the defective gene or genes are carried on the sex chromosomes. (Each dog has 39 pairs of chromosomes which carry all of his or her genes. One member of each pair is inherited from each of the parents. Thirty-eight of these pairs are autosomes and one pair is the sex chromosomes.) Often, when there are sex differences in a trait, the gene for that trait is carried on the sex chromosomes. However, despite the fact that many breeds (though not all) show a higher rate of epilepsy in males than females, the pattern of inheritance across generations suggests that the genes responsible for epilepsy are probably carried on one or more of the autosome pairs. While these two theoretical notions (recessive and autosomal) may indeed prove to be true for many breeds, at the present time, there still is not enough data to draw any firm conclusions, even on the specific breeds for which pedigree analyses have been conducted.
As indicated, there are several researchers who currently are investigating the genetic basis of canine idiopathic epilepsy. If you own a dog with idiopathic epilepsy, or one of your dogs has produced offspring with epilepsy, please contact the canine epilepsy network.”
IF your dog has seizures it is important to notify the breeder and any association or clubs to which they belong. It is only through shared information and pedigree study that genetic conditions can be identified and used to breed wisely.
IDENTIFY SEIZURES (WHEN IS IT AN EMERGENCY?)
Generalized Seizure or Tonic-clonic: The Tonic-clonic seizure has two stages and may come in a mild or Grand Mal version. During the Grand Mal seizure the “tonic” phase is when the dog falls to the ground, rigidly stretches his legs out and loses consciousness. During this time his breathing will also stop. This part of the seizure usually lasts ten to thirty seconds. After this the “clonic” stage begins. It is at this time that owners notice the stereotypical activity that is commonly called a fit.
While the dog is in the clonic stage, he or she will begin any or all of the following symptoms:
1. Paddling of limbs or “running in place”.
2. Jaw movements that look like the dog is trying to chew gum.
3. Pupils in both eyes dilate (become large) and unresponsive.
4. Dog begins salivating or drooling.
5. Dog loses control of bodily functions and begins to urinate or defecate on itself.
TYPES of SEIZURES
In the mild cases of Tonic-clonic seizures there is usually little paddling and no loss of consciousness. Defecation and urination may also not occur.
Petit Mal Seizures have short episodes of the dog being unconscious with instances of muscle tone loss, and blank stares. These types of seizures seem to be very rare in dogs and often require the presence of EEG abnormalities to diagnosis for certainty.
Partial Seizures are odd things where the seizure activities such as the leg paddling, muscle spasms, neck and head bending or the main part of the body and facial muscle spasms only occur in one part of the body. These types of seizures can worsen until they appear to be Grand Mal or Mild Tonic-clonic but the difference is how the seizure began. Both Tonic-clonic types seem to be overall body from the start but the partials may just start at the face or one hip.
Status Epilepticus type seizures can be life threatening. They can appear as one continuous seizure that lasts more than thirty minutes or in a repetitive loop of seizures with the dog never regaining consciousness. Status epilepticus seizures can occur to dogs with a history of Grand Mal or Mild Tonic-clonic seizures and a diagnosis of epilepsy. They can also occur in dogs with no previous seizure activity but that have had an injury to the brain, exposed to toxins such as massive amounts of chocolate, pesticides and poisons or they can be the result of disease.
Cluster Seizures are very similar to the loop of status epilepticus seizures and each are often diagnosed as the other. The difference between the status epilepticus and the cluster seizures is that the dog actually has short time periods returning to consciousness in between each seizure.