Epilepsy And Seizures In Your Dog And Cat
Ron Hines DVM PhD
It is wise to screen dogs and cats that do not improve on epilepsy/seizure medications for high blood ammonia levels and/or elevated bile acid levels. Both can be the cause or the result of seizures. When either are elevated, liver issues such as portosystemic shunts or other liver disease could be the underlying causes of the seizures. ( read here & here )
Epilepsy is a disease in which your dog or cat is subject to recurrent seizures or convulsions. It is quite similar in its appearance to the epilepsy that occurs in people. Seizures result from many causes. Not all seizures or convulsions in dogs or cats are due to common epilepsy (less than half are). The older your dog or cat is when it experiences its first seizure and the presence of an residual brain-related abnormalities between seizures decrease the likelihood that your pet has idiopathic or common epilepsy. ( read here )
Idiopathic just means that your veterinarian does not know why something occurred. Once we have eliminated all other possible causes for repeating seizures, we are left with a probable diagnosis of common (= simple, true, idiopathic or inherited) epilepsy. In idiopathic/common epilepsy, veterinarians find no underlying physical or chemical problems that might be the seizure cause when your pet is not in the midst or recovering from a seizure. All the blood tests, all the x-rays and all the examinations generally come back as normal or as not related to the seizures. But medical diagnostic equipment is becoming more sophisticated as time goes by. So it is probably only a matter of time until we will be able to see what the physical problem actually is in your epileptic pet. (read here & here )
What Dogs And Cats Are Most Likely To Become Epileptic?
Any breed of dog or cat can develop epilepsy. But golden retrievers, beagles, cocker spaniels, dachshunds, German shepherds, Irish setters, schnauzers, and huskies seem to have more than their fair share of epileptic problems. Seizures also occur more frequently in staffordshire bull terriers ; but those seizures are usually related to a specific neuro-metabolic disorder seen in that breed. ( read here ) Epilepsy is less common in cats. When idiopathic epilepsy affects them, it is seen most frequently in Persian and Siamese cats. A more common cause of seizures in cats is the “dry form” of FIP.
Epilepsy effects specific dog and cat blood-lines (extended families) within a breed more frequently than others. (read here) So veterinarians believe that idiopathic epilepsy (the kind that is usually relatively stable from month to month and year to year) is most often a genetically-transmitted or inherited disease. ( read here ) Usually, a parent or a close relative of your pet also had epilepsy. In young adult dogs, the majority of epilepsy cases are of that non-progressive, inherited form. The underlying genetic causes of idiopathic epilepsy in cats are less known because epilepsy in cats is less common and less studied.
In cats that experience seizures, only about a third to a quarter of the cases are the non-progressive, idiopathic form. In cats, brain inflammations (encephalitis), as yet unexplained degenerative changes in the cat’s hippocampal portion of the brain , exposure to toxic substances, flea and tick control products, traumatic brain injuries, abnormal body metabolism, brain tumors and feline infectious peritonitis / FIP which I mentioned earlier account for most of the rest. (see more on causes of seizures in cats farther down in this article) Your cat is more likely to be among the fortunate quarter or third that do have idiopathic epilepsy if it is less than 3.5 years of age when the problem first begins and is negative for feline immunodeficiency virus , Feline leukemia , and behaves perfectly normal between seizures.
It is easy to get confused regarding seizures. All epileptic pets have seizures; but not all pets that have had seizure(s) have epilepsy.
What Is Happening Inside My Pet During A Seizure?
It is always very frightening to watch a dog or cat experiencing a seizure. Try to keep in mind that during that frightening experience your pet experiences no pain. Your dog or cat might vocalize, thrash around, or void its bladder and intestines, but it does not experience painful sensations. It is just before and just after a seizure that your pet is likely to be frightened and confused. It needs your reassurance then.
An epileptic seizure is like lightening in a thunderstorm. During the seizure, random electrical impulses are being sent from nerve cells in your dog or cat’s brain to muscles throughout its body. The source of these abnormal brain impulses are small areas of abnormally active or damaged brain tissue. Although during a complete epileptic seizure your pet looses consciousness and has no memory of the event ever occurring, there are instances in some pets (and people) where the seizure is partial and the pet is at least somewhat aware of you and things that are occurring around it. Their judgment and behavior in those situations is flawed so your must be very cautious in interacting with them.
Physicians and veterinarians attempt to subdivide seizure types by the signs that occur and the areas of the brain that they believe are involved. However, there is considerable overlap, the terms are imprecise and a lot of disagreement exits. But here is what we were taught in school: Seizures that put the whole body into severe muscle contractions, are called grand mal seizures. Seizures that are less severe, only affect a few muscle groups or are no more than a brief fainting experience, are sometimes referred to as petit mal or absence seizures. Status epilepticus and cluster seizures are terms used for severe seizures that occur again and again with little or no rest between convulsions. Status epilepticus is exhaustive and can be fatal. Those pets need to be taken immediately to their veterinarians so that the seizure can be broken with injected medications.
During a seizure, the tiny abnormal areas of your pet’s brain that I mentioned begin sending out electrical impulses that are received by the nerve cells that adjoin them. This result can be a chain reaction (a “storm”) in which the surrounding nerve cells are stimulated to fire off a shower of signals of their own to various body muscles. When this occurs it is, in many respects, much like a single snowball setting of a great avalanche.
Secondary Epilepsy and Seizures:
When sophisticated tests (only available in institutional veterinary settings) detect the specific area within your pet’s brain (such as a tumor (read here) or localized inflammation (read here) that is generating the abnormal impulses, veterinarians might describe your dog or cat’s situation as symptomatic or secondary epilepsy. More commonly, secondary seizures occur when fluid pressure within the pet’s brain is too high (intracranial pressure). Seizures can also occur when the brain is inflamed (meningitis) for any reason. (read here) The same drugs used for idiopathic epilepsy might control those type of seizures for a while ; but unless the underlying cause is determined and successfully treated, the pet’ long term outlook is grave.
Things outside the brain can cause convulsions too. Things like overheating (hyperthermia), low blood glucose (hypoglycemia ), intestinal inflammation or the toxin build up of liver or kidney failure (that’s the reason your vet has to run all those tests). Certain poisons and toxic chemicals can also cause seizures. For example, certain flame retardant chemicals, when eaten, have the ability to cause seizures. ( read here ). Those same organophosphate compounds are common insecticides. Never use any insecticide-containing product on your dog or cat unless it specifically says that it is FDA/EMA-approved for use on a pet of your species and of your pet’s age. Using two different insecticide products at similar times – even at their suggested doses – is also dangerous. On occasion, Thiamine-deficient diets have also been reported to caused seizures in cats. ( read here ) Pets accidentally consuming xylitol-containing products can also result in seizures because they cause such a sudden drop in your pet’s blood sugar level. ( read here )
More On Epilepsy In Cats:
As I mentioned earlier, idiopathic epilepsy is much less common in cats than in dogs. Cats are considerably more likely to develop seizures because of some progressive, acquired disease that is affecting their brain. Because many of these underlying causes have no current effective treatments and tend to increase in severity over time, the long-term prognosis (outlook) for seizuring cats is not nearly as good as it is for dogs. But even in those cats, your veterinarian can often control the seizures with medications – at least for a time. Because of the high incidence of inbreeding, veterinarians see more idiopathic or common epilepsy in pure-bred cats than in randomly-bred house cats. The same pass-on-to-offspring effect occurs in some epileptic people. (read here)
When In My Pet’s Life Does Epilepsy Usually Start? What Will I See?
Most dogs and cats experience their first epilepsy seizures between 1 and 5 five years of age. During a complete seizure, your pet typically falls on its side with its legs outstretched and it’s back arched. Partial seizures have much more variable signs. Most pets maintain their legs rigidly extended, but some paddle as if they were running. Your pet might whine or vocalize – although it is not in pain.
Dogs and cats in this situation often void their bowels and bladder during their convulsions. Their jaws are usually clenched during the first phase of the seizure. If only a portion of the body is affected by the seizure your pet might remain consciousness. but its reasoning abilities and mental abilities (mentation) are generally flawed until a few minutes after the seizure has passed.
Some forms of focal epileptic seizures or partial epilepsy are misinterpreted by owners as just a periodic quirky behavior. Sometimes muscles of the face just go into a jerky motion. Sometimes the pets appear to be snapping at invisible flies or chewing gum or running round and round in circles. In dogs, that form of behavior can also be a lifelong residual effect of exposure to the canine distemper virus.
Frontal Lobe Epilepsy
Some seizures primarily affect the portions of your pet’s brain that control thought rather than motion. When those areas of the brain that control conscious thought processes are affected, the seizure is often called a psychomotor seizure or hallucination. In humans this form of seizure is called frontal lobe epilepsy. During these altered period of consciousness, your dog or cat might only show fear. In other pets with psychomotor seizures, aggression, growling hyperactivity, or repetitive nonsensical behaviors are the prevailing signs. Some pets hear imaginary noises. Your pet might bite or snap at you if you disturb it during one of those episodes. Now and then, dog owners tell me that their pet had a “bad dream” – perhaps that was all it was – perhaps there was more to it than that. I see those sudden strange behavior episodes more frequently in cats than in dogs.
Because so many areas of your pet’s brain can give rise to epileptic seizures, no two will exhibit exactly the same signs and behaviors. In some lucky instances seizures will be a one-time episode never to occur again. In other pets the problem reoccurs at regular intervals of from every several days to a few times a year. Common older medications (such as phenobarbital) used to treat epilepsy can damage your pet’s liver over time. Only you, not your veterinarian, can decide if the number and severity of seizures your pet experiences, justify the risks of continuous lifetime administration of those medications.
Stages Of A Seizure
An epileptic seizure event can be broken down into three distinct stages. Epilepsy is an ancient disease – written about since writing was invented – so the event has been divided in many ways using many confusing terms with considerable disagreements and overlap. Human nature being what it is, various commissions, study groups and poobahs feel compelled to change these terms and classifications at just about the time that physicians, veterinarians and the public become comfortable with the terms that are currently in use.
The first stage is often called the prodromal, or the warning stage. This stage usually lasts several minutes but can last much longer. During this stage, your dog or cat might have changes in its mood and behavior and might appear anxious. Some common signs are restlessness, wandering, pacing, licking, trembling and vomiting. In epileptic people, therapy dogs have been used to warn dog owners during this early stage that a seizure in their owner is eminent. Results as to these dog’s abilities are mixed. (read here)
The next stage of an epileptic seizure was once called the ictus or ictical stage. This is the time of the seizure itself when the body is subject to uncontrolled movement and thrashing due to the electrical “storm” in its brain. During this stage in a complete seizure, the pet is unconscious. Paddling or swimming movements, clenched teeth, and arched back are common during this stage. In cases where partial seizures occur, the pet may run in circles, or appear blind or deaf.
The final stage of an epileptic seizure is called the postictal stage. This is the stage of gradual recovery. Dogs and cats in the postictal stage usually appear dazed or hung over. They may bump into objects. These pets are exhausted and tend to sleep a lot until full recovery. They might have a blank expression or appear to stare out into space.
What Tests Will My Veterinarian Run To Confirm That My Pet Has Epilepsy?
After a thorough physical examination , your veterinarian will likely want to begin with a complete blood chemistry panel panel as well as a urinalysis of your pet’s urine. If your pet is young or in mid-life and has simple or idiopathic epilepsy, these tests will probably all come back normal. Your pet’sT4 thyroid test could be low if the pet is already taking phenobarbital. ( read here ) If your veterinarian is reasonably certain of the diagnosis at that point, he/she might wait to see if the seizures return or begin your pet on anti-epileptic medications. I always wait until a repeat seizure pattern is established unless a pet owner demands otherwise. When the diagnosis remains uncertain, your vet might go on to order more specialized tests, such as an MRI, CT scan or even a cerebrospinal tap . Veterinarians often find it safer to obtain that fluid higher up at the base of the pet’s skull rather than low in the back we do in humans.
What Should I Do During My Pet’s Seizure?
When a first seizure occurs, owners tend to rush their pets to an emergency veterinary center. There is not much that can be done there for idiopathic epilepsy; but it is a wise thing to do considering all the serious conditions that can mimic epilepsy and that prolonged seizures need to be broken with Valium®. Luckily, most epileptic seizures last only a few minutes. One to three minute seizures are most common. Those that last five to ten minutes are less common and more serious. I have never seen or heard of a dog that swallowed its tongue during a seizure. During a prolonged seizure, a dog’s tongue and mouth can turn purple (cyanosis). But that is because it is having difficulty breathing, not because its airway passage is obstructed by its tongue. Certain breeds with short faces (like bulldogs) spend their lives with borderline respiratory passage obstruction. Those pets, in seizure, are probably at considerably more risk than others.
Seizures that last longer than 5 minutes can become medical emergencies since those pets are having trouble breathing. Have your veterinarian provide you with an emergency vial of diazepam (Valium®) if you pet has experienced such seizures in the past. The standard diazepam bottle says to give the liquid by intravenous or intramuscular injection. Most pet owners might not be capable of that. But it can be placed up the pet’s rectum where it is quickly absorbed. Your vet or their tech will show you how that is done. Diazepam is also sold in an auto-injector. (read here) I do not know if the dose can be calibrated and I have no experience using it. Give nothing by mouth.
My first concern for you is that you NOT TO BE BITTEN. Do not ever put your hands in or near a seizuring pet’s mouth. If your pet or a neighbor’s pet develops a seizure, begin by cautiously manipulating the pet’s head onto a soft folded towel. You may carry the pet in a blanket to a secluded tiled area. Remove all objects that surround the pet so it does not injure itself. Protect it from overheating and stay beside it until the seizure ends. Keep the room darkened, cool and keep other family members away. You can already position some paper towels and warm soapy water on a wash stand beyond the pet’s reach to help clean up any mess.
How Soon Should I Start To Think About Continuous Medications For My Pet?
This is a difficult question to answer. After an initial work up, I generally suggest that dogs and cats receive anti-seizure medications if they have had two or more seizures within an 12-14 week period or two or more cluster seizures (acute repetitive seizures) within a 4 week period. Dogs and cats that show unusually severe ictal or postictal periods should probably begin medication sooner – with dose and need periodically reevaluated thereafter. When seizures are rare, how frequently (if ever) that you as the pet owning family can tolerate the sight of a seizure can also be a deciding factor.
What Medications Are Available To Treat Epilepsy In My Pet?
Human physicians can be a bit more confident than veterinarians when they formulate a complex epilepsy treatment plan. Veterinarians have a long experience in using phenobarbital and potassium bromide in pets; but only a few limited veterinary studies have been published regarding the long term use of the newer human products in dogs and cats. (read here) Please do remember that idiopathic epilepsy is only an umbrella term for an enormous number of possible epilepsy triggers within your pet’s brain. As in humans, a few epileptic dogs and cats are resistant to all medications that your veterinarian might have at his/her disposal to prescribe. ( read here )
Phenobarbital (aka Phenobarbitone)
Phenobarbital was the most commonly used drug to treat epilepsy in dogs and cats. (the second most common treatment that was phenobarbital combined with potassium bromide ). Both medications are still in common use. But the addition or substitution of more recent medications successful for human epileptics is making their use less common. Your pet’s ideal phenobarbital dose is best determined through measurement of its blood serum phenobarbital levels after it has been on a trial dose of the drug for some time and periodically there after. Phenobarbital can have negative effects on your pet’s liver. That is why I previous suggested liver function tests (including bile acids) be run periodically. The side effects of phenobarbital are dose-dependent sedation, increased appetite, weight gain, increased thirst and urination. It is impossible to predict which pets will show any of those side effects and to what degree. Many of these side effects decrease after their bodies have adjusted to the medications. These problems, when they are significant, can often be minimized when the dose is closely regulated or if a cocktail of medications is used that lowers the required phenobarbital dose. My articles on NeuroCare™ and MCTs suggest other possible ways. Phenobarbital works well to control epilepsy in both dogs and cats. Cats do not seem as prone as dogs to liver damage while on this drug, but they do tend to gain weight.
Some veterinarians suggest give epileptic pets milk thistle as a liver protectant. A scientific study of milk thistle’s “active” ingredient, silymarin, found it of little or no value in humans with one form of chronic hepatitis. ( read here ) Another study had reached a similar conclusion on silymarin’s its use in various other human liver problems. ( read here ) Silymarin is one of the two “active” ingredients in Denamarin™. A study on silymarin’s use as a liver protectant in overweight mice was considerably more up beat.) ( read here )
Combining phenobarbital with a second drug, such as potassium bromide , may lessen the chances of liver damage in your pet by allowing a lower phenobarbital dose. Dogs taking potassium bromide (KBr) should receive it with food. Owners need to be careful with the salt levels in their pet’s diet and whenever the brand of dog food they offer is changed [higher salt diets and salty treats can decrease the level of KBr in their body. ( read here ) Their T4 levels and serum bromide concentrations need to be periodically monitored. (read here) The most common side effects of this drug are behavioral changes, muscular twitching and staggered gait. Potassium bromide occasionally produces other side effects. An article in the AVMA Journal about that is protected by a paywall (they want money before they will allow you to read it). But if you ask me for Baird-Heinz2012 I will loan you my copy. Most veterinarians rely on phenobarbital to get your pet’s seizures under control and then add potassium bromide as a second line medication to keep the pets phenobarbital dose as low as possible. It is rarely used at this time as the primary seizure-control medication.
Cats do not respond as well to potassium bromide as dogs do. The use of this medication in cats has also been associated with a type of lung inflammation called pneumonitis. ( read here ) When pneumonitis occurs, it can produce signs quite similar to feline asthma .
Primadone (Mysoline®, Mylepsin®, etc.)
The effects and side effects of primadone are similar to those of phenobarbital. That is because the majority of primadone is converted to phenobarbital in your pet’s body. In the majority of studies I know of, primadone was no better or safer than phenobarbital in controlling seizures. In most studies, primadone was a bit less effective than phenobarbital, and in none of the studies I know of was it any better than phenobarbital.
Imepitoin ( Pexion® )
For a number of years,Pexion® was available to veterinarians in Europe, the UK and Australia to treat epilepsy – but not in North America. No one at the company that markets it, Boehringer Ingelheim Vetmedica Inc, offered me an explanation for that. I am guessing it was due to bureaucratic hurdles that they believed were not cost effective. The epileptic pet medication market is small. But in 2018, the FDA approved its use in the United States for noise aversion (fear of loud noises) in dogs. Nothing was said about epilepsy. But veterinarians, after explaining the situation to pet owners, are usually free to make their own decisions regarding medication use (“off label prescribing”). Read about Pexion® and epilepsy here. If you have experience using it to control epilepsy in your dog (or cat) let me know.
Valium® ( diazepam )
Diazepam , given alone, is only effective in ending dangerous long-lasting seizures until another medicine can take over long term seizure control in your dog or cat. In dogs and cats, diazepam is quite successful in breaking (ending) those persistent, dangerous seizure. But when diazepam is given over longer periods of time, the body becomes resistant to its effects. It can be an effective “add-on” medication for epileptic cats because positive effects of maintenance doses of diazepam seems to persist longer in feline than canine patients.
Levetiracetam, a human anti-epileptic drug, is sometimes used in dogs in combination with phenobarbital and potassium bromide (KBR) to lower the daily dose of the phenobarbital and/or KBR received. It is also given in cases where phenobarbital and potassium bromide were not able to control your pet’s seizures adequately. (read here) In one study, the drug did not appear to be able to control seizures in dogs adequately when given alone. (read here) Another study found it was occasionally effective alone (monotherapy). (read here) A major drawback is that the medication has a short half-life in the body; so it must be given several times a day. Rare side effects in dogs include stiff wobbly gait, vomiting and salivation. Levetracetam does appear to be an effective add-on medication for epileptic cats as well. (read here) It also appears that the medication is also effective in cats when it is applied to the inner side of their ear as a topical cream. Read about that here.
Zonisamide ( Zonegran ®)
Zonisamide is sometimes effective in blocking seizures in dogs and cats. It does have a few common side effects that we know of. If they occur they are generally mild (vomiting, reduced appetite, sedation,or a wobbly gait). ( read here & here) Occasionally, side effects are more severe ( read here , here , here & here ) If I were to dispense this medication, I would begin at a very low dose and follow the pet’s liver and kidney function test results closely along with frequent feedback from the pet’s owner. More cats than dogs seem to have side effects from this medication. It is available in generic form. Zonisamide can also cause a pet’s thyroid hormone (T4) levels to decrease. So it might be wise to document your pet’s T4 level as well before beginning the drug. When zonisamide is used, it is often as an add-on therapy for dogs already receiving phenobarbital. When added, the phenobarbital dosage can sometimes be drastically reduced (in a few cases, entirely eliminated). Unlike levetiracetam, it can be effective when given twice, rather than three times a day.
Can I Ever Stop Giving My Dog Or Cat These Medications?
Probably not. Adding supportive secondary medications that keep you dog or cat as functionally normal as possible after its initial period on a medication that commonly produce side effects is always a good plan. So is attempting to find the lowest effective doses of all of them that keeps your pet seizure-free or keeps seizures to a minimum is always desirable. All changes need to be gradual and done in consultation with your veterinarian. Try to make those changes when your household is not under stress and when you know that your favorite veterinarian is available or on call.
In my experience, very few truly epileptic dogs and cats cure themselves and stay seizure-free without any medication. But it probably occasionally happens. It does in humans. ( read here ) Some of the dogs and cats that were put on long-term phenobarbital and other medications because they had one or two seizures with little laboratory and physical work ups and no family history of the problem probably shouldn’t have been on it at all.
Might My Pet’s Diet Affect The Number and Intensity of Its Seizures?
There is some evidence that in humans at least, diets high in fat and low in carbohydrate might be beneficial in controlling epilepsy. You can read a review of that information here. Although it is not a true ketogenic diet, be sure to read my link to Purina’s NeuroCare™ diet as well. Unfortunately, Purina has never released any scientific data that I know of to show that it is effective in controlling epilepsy or forgetfulness. Never-the-less, I suggest you give NeuroCare a try. (read here) If you do, let me know what results you observed and I will set up an owner’s comments page.
You might also try to slowly changing the amounts you feed at each meal and the frequency between them. Smaller, more frequent feeding are known to change many aspects of metabolism – sometimes for the better. Periodic fasting was the only thing that Hippocrates knew of that would lessen the “falling sickness” . I am not suggesting that for your pet, but I thought that you might like to know.
Will Idiopathic Epilepsy Shorten My Dog Or Cat’s Life?
Typically, idiopathic epilepsy does not greatly shorten a dog or cat’s life. (read here) It is only in dogs and cats that have progressive brain disease that is triggering seizures that become ever more severe and those with other concurrent health issues that eventually pass away earlier. My advice to you is to feed you epileptic dog and cat a diet relatively high in MCT and animal fat. (read here) I prefer dog and cat diets you prepare at home. Or, with a copy of my last read me citation, a university veterinary nutritionist such as one of those authors could always prepare such a diet recipe for you.