Overview Epilepsy is found in all breeds and mixed breeds of dogs. German Shepherd Dogs are listed among the breeds for which a genetic factor is either proved or highly suspected. The prevalence of epilepsy in the general dog population has been estimated at .5 to 5.7%.The term "epilepsy" can be confusing because some authors use it to describe recurrent seizures of any etiology (cause), while others use it to specify recurrent seizures unrelated to brain disorders or underlying disease processes. The definitions below are helpful in distinguishing types of epilepsy.
Types of Epilepsy Primary epilepsy: also known as idiopathic, genetic, inherited, or true epilepsy. There are no positive diagnostic findings that will substantiate the diagnosis. It is a case of ruling out every other possibility. The first seizure in a dog with primary epilepsy usually occurs between the ages of 6 months and 5 years. However, a diagnosis of primary epilepsy is not proof of a genetic defect; only careful breeding studies could prove that. The breed, the age, and the history may suggest a genetic basis for primary epilepsy if there is a familial history of seizures.
Secondary epilepsy refers to seizures for which a cause can be determined, and there are many. In dogs less than one year of age, the most commonly-found causes of seizures can be broken down into the following classes: degenerative (storage diseases); developmental (hydrocephalus); toxic (lead, arsenic, organophosphates, chlorinated hydrocarbons, strychnine, tetanus); infectious (distemper, encephalitis, and others); metabolic (such as transient hypoglycemia, enzyme deficiency, liver or kidney failure); nutritional (thiamine, parasitism); and traumatic (acute injury). In dogs 1-3 years of age, a genetic factor is most highly suspected. In dogs 4 years of age and older, seizures are commonly found in the metabolic (hypoglycemia, cardiovascular arrhythmia, hypocalcemia, cirrhosis) and neoplastic (brain tumor) classes. It is thought that seizures are also associated with hypothyroidism, which is a familial (inherited) autoimmune disease of purebred dogs.
Types of Seizures The types of seizures most commonly reported are listed below. If you believe your dog is having a seizure, it is important to note all the details so that you may accurately describe it to your veterinarian. Types of seizures include:
Tonic-clonic (may be Grand Mal or Mild): In the grand mal seizure, the tonic phase occurs as the animal falls, loses consciousness, and extends its limbs rigidly. Respiration also stops (apnea). This phase usually lasts 10-30 seconds before the clonic phase begins. Clonic movements include paddling of the limbs and/or chewing. Other signs that appear during the tonic or clonic phase are dilation of the pupils, salivation, urination, and defecation. The mild seizure involves little or no paddling or extension of limbs, and usually no loss of consciousness. Generalized seizures are usually associated with primary epilepsy.
Petit Mal Seizure (aka Absence Seizure): Depending on the authority quoted, petit mals are described as either very rare or usually unrecognized in animals. Signs are brief (seconds) duration of unconsciousness, loss of muscle tone, blank stare, and possibly upward rotation of eyes. According to one authority (Kay), the term petit mal is misused by veterinarians and should only be accorded to cases manifesting very specific clinical signs and EEG abnormalities.
Partial Seizures: Movements are restricted to one area of the body, such as muscle jerking, movement of one limb, turning the head or bending the trunk to one side, or facial twitches. A partial seizure can progress to (and be mistaken for) a generalized tonic-clonic seizure, but the difference can be established by noting whether or not a seizure starts with one specific area of the body. Partial seizures are usually associated with secondary epilepsy.
Complex Partial Seizures (aka Psychomotor or Behavioral Seizures): are associated with bizarre or complex behaviors that are repeated during each seizure. People with complex partial seizures experience distortions of thought, perception or emotion (usually fear), sometimes with unusual visual, olfactory, auditory and gustatory sensations. If dogs experience the same things, it may explain the lip-smacking, chewing, fly biting, aggression, vocalization, hysterical running, cowering or hiding in otherwise normal animals. Vomiting, diarrhea, abdominal distress, salivation, blindness, unusual thirst or appetite, and flank biting are other signs. There is an obvious lack of awareness though usually not lack of consciousness. Abnormal behaviors may last minutes or hours and can be followed by a generalized seizure. Complex partial seizures are usually associated with secondary epilepsy.
Cluster Seizures: Multiple seizures within a short period of time with only brief periods of consciousness in between.May be confused with status epilepticus.Cluster seizures are considered LIFE-THREATENING emergencies. Status Epilepticus: Status can occur as one continuous seizure lasting 30 minutes or more, or a series of multiple seizures in a short time with no periods of normal consciousness. It can be difficult to tell status epilepticus from frequent cluster seizures. Status Epilepticus are considered LIFE-THREATENING emergencies. Most status patients usually suffer from generalized tonic-clonic seizures. Though status epilepticus can occur with either primary or secondary epilepsy, it may also suddenly arise in dogs with no previous history of seizures (traumatic brain injury, toxins, or disease).
Diagnosing Epilepsy What do you do if you think your dog has had a seizure? Veterinarians have a number of diagnostic tools at their disposal.
For dogs who have had only one isolated seizure, a complete physical and neurological examination is in order. Owners will be advised to watch for further seizures if no abnormalities are found. Medical treatment will not be instituted until future activity can be noted. For every patient having more than one seizure, a minimum data base should be developed. The data base contains the patient's profile, history, results of complete physical and neurological examinations, and basic tests. The profile consists of the dog's breed, age, and sex. Pertinent history includes vaccinations, potential exposure to toxins, diet, any illnesses or injuries, behavioral changes, and whether seizures occurred in any animal related to the dog. Owners are also asked to give a complete description of the seizures: frequency, duration, and severity, as well as any behavioral abnormalities associated with them. An accurate description is important because there are other conditions with symptoms that mimic seizures, such as cardiac and/or pulmonary disease, narcolepsy, cataplexy, myasthenia gravis, and metabolic disturbances.
Among the recommended tests are: CBC, urinalysis, BUN, ALT, ALP, calcium, fasting blood glucose level, serum glucose level, serum lead level, fecal parasite or ova examination, and others if indicated. When the results of the examinations and tests have been analyzed, one of three conclusions will be drawn: a definitive diagnosis a potential cause of seizures requiring further tests to confirm or no suggestion of a cause. When further tests are required a complete date base should be done. This may include computed tomography or magnetic resonance imaging; CSF analysis (cell count, protein levels, pressure), skull radiographs, and an EEG.
Treatment Drug Treatment Medical treatment is generally advised for animals who have one or more seizures per month. Animals who have cluster seizures or go into status epilepticus may be treated even though the rate of incidence is greater than once per month. Successful drug therapy depends upon the owner's dedication to delivering the drug exactly as prescribed, with absolutely NO changes in the dose or type of medication without veterinary consultation. Haphazard drug administration or abrupt changes in medication is worse than no treatment at all, and may cause status epilepticus. It may not be possible to stop the seizures altogether. A number of drugs and some alternative therapies may be used to control epilepsy. Phenobarbitol and primidone are the most widely used anticonvulsant drugs, but others have their place in treatment as well.
Acupuncture Acupuncture is not usually considered a substitute for drug therapy, but is used in conjunction with them. Of 5 dogs with intractable epilepsy, followed after gold bead implants in acupuncture points, 2 dogs relapsed after five months. Two reports of epileptic dogs given acupuncture in the ear (Shen-men point) are more positive. One dog enjoyed a six-fold increase in time between seizures; the other was seizure-free for 200 days after a previous history of monthly seizures.