Epilepsy And Seizures In Your Dog Or Cat
Ron Hines DVM PhD
Epilepsy
Epilepsy subjects your dog or your cat to recurrent seizures or convulsions. Seizures in pets have many causes. Less than half of the time, they are due to common or idiopathic epilepsy. The older your dog or your cat is when it experiences its first seizure, the less likely it is that its problem is common epilepsy. The presence of abnormal behavior between your pet’s seizures also greatly decrease the likelihood that it has idiopathic or common epilepsy. (read here)
Idiopathic just means that your veterinarian does not know why it is occurring – all blood tests are normal, its physical examination is normal, x-rays and ultrasound examinations are normal. Once your veterinarian has eliminated all the other possible causes for repeat seizures, your vet is left with a diagnosis of common epilepsy. That form of epilepsy is an inherited disease. Its underlying causes are unknown today. But medical equipment becomes more sophisticated as time goes by. It is only a matter of time until scientists will actually see what is physically or chemically different between epileptic and non-epileptic dogs and cats. (read here & here)
Idiopathic epilepsy is quite rare in cats. In fact, many veterinary neurologists believe that idiopathic epilepsy does not occur in cats. So if your cat develops seizures, most of those veterinary specialists will assume that something more serious is going on – until proving that that is not the case. The exceptions are cats with focal seizures or twitching. During these episodes, they are aware of what is going on around them. They sometimes twitch their eyelids, whiskers, or ears. Cat owners might just consider that to be a quirk. Those cats are born with that tendency and usually remain stable, without medication, for many years. (read here) However, if your cat’s problem becomes worse over time, there are many more serious underlying causes that are possible. Read about them here. If your cat’s problem is stable and not debilitating, you might reconsider advice to place it on lifetime medications, since none of them are curative and many have potential unwanted cognitive and/or metabolic side effects. (read here & here)
In cats, brain inflammations (encephalitis), as yet unexplained degenerative changes in your cat’s hippocampal portion of its brain, exposure to toxic substances, flea and tick control product sensitivity, traumatic brain injuries, abnormal body metabolism, brain tumors and feline infectious peritonitis / FIP which I mentioned earlier, account for most feline seizures. Your cat is more likely to be among the fortunate few who have idiopathic epilepsy if it was less than 3.5 years old when the problem first began, if it is negative for feline immunodeficiency virus and Feline leukemia, and if it behaves normal between seizures.
What Breeds Are At Greater Risk?
Any breed of dog or cat can develop common 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. (read here) 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) As I mentioned, epilepsy is much less common in cats. When idiopathic epilepsy affects them, it is seen most frequently in Persian and Siamese cats. Unfortunately, the most common cause of seizures in cats is probably the “dry form” of FIP.
As I mentioned, common/idiopathic epilepsy effects specific dog and cat blood-lines (extended families within a breed) more frequently than others or mixed heritage mutts. So, veterinarians believe that the majority of cases are genetically transmitted. (read here) Usually, a parent or a close relative of your dog also suffered from epilepsy. In young adult dogs, the majority of epilepsy cases are of that non-progressive, inherited type. The underlying genetic causes of idiopathic epilepsy in cats are less understood because epilepsy in cats is less common and less studied. For reasons unknown, Australian shepherds, border collies, huskies, German shepherds and leonbergers appear to be less responsive to common anti-seizure medications than other dog breeds.
What Is Happening Inside My Pet During A Seizure?
It is always frightening to watch a dog or a cat experience a seizure. Try to keep in mind that during that frightening experience your pet experiences no pain. It might vocalize, thrash around, or void its bladder and bowels, but it does not experience painful sensations, fear or anxiety. It is just before and just after a seizure that your pet is likely to be frightened and confused. You need to reassure it then.
An epileptic seizure is like lightening in a thunderstorm within the brain. During the seizure, random electrical impulses are being sent from nerve cells to muscles throughout its body. In non-idiopathic epilepsy, the source of these abnormal brain impulses are small areas of abnormally active or damaged brain tissue. Going into and coming out of of a seizure, your pet’s judgment and behavior is flawed. So, you must be very cautious in interacting with your friend.
When idiopathic/common epilepsy is not your pet’s underlying seizure cause, veterinarians attempt to subdivide seizure types by the signs that occur, and the area(s) of your pet’s brain that are involved. However, there is considerable overlap, the terms used are imprecise and a lot of disagreement exits. In simpler times, here is what veterinarians 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 episode, 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 the convulsions. Status epilepticus is exhaustive and it can be fatal. Those pets need to be taken immediately to their veterinarians so that the seizure can be broken with injectable medications.
Secondary Epilepsy and Seizures:
Sophisticated tests – only available in large institutional veterinary settings – can sometimes detect specific area(s) within your dog or cat’s brain such as a tumor (read here) or localized inflammation. (read here) If they believe that that area is generating the abnormal brain electrical activity, those veterinarians might describe your dog or cat’s situation as symptomatic or secondary epilepsy. Secondary seizures also occur when fluid pressure within your pet’s brain is too high (increased intracranial pressure). Seizures can also occur when your pet’s brain is inflamed (meningitis). (read here) The same drugs used for idiopathic epilepsy might control those types of seizures for a while. But unless the underlying cause is determined and successfully treated, your pet’ long-term outlook is grave.
Things outside your pet’s brain can cause convulsions too. Events like overheating (hyperthermia), low blood glucose (hypoglycemia), intestinal inflammation or the toxin build up that occurs in liver or kidney failure. That is the reason your veterinarian has to run so many expensive tests. Certain poisons and toxic chemicals can also cause seizures. For example, some flame retardant chemicals, when eaten, have the ability to produce seizures. (read here). Those same organophosphate compounds are also common insecticides. Some dogs are quite sensitive to the common topical insecticides used to control ticks and fleas. 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 cause seizures in cats. (read here) Pets that accidentally consume xylitol-containing products can also experience seizures because sufficient xylitol ingestion causes a sudden drop in their blood sugar level. (read here) The theobromine and caffeine in chocolate is also a common cause of seizures in dogs. It is less of a problem in cats because most cats are less drawn to chocolate. The newer oral flea and tick control products have also been associated with seizures. (read here) There are many other possible causes as well. (read here) In dogs, seizures and tremors can be a lifelong residual effect of exposure to the canine distemper virus. Feline distemper is not known to have that long-term effect.
Frontal Lobe Epilepsy
Sometimes, seizures affect a different portion of your pet’s brain. The one that control thought rather than motion. When those areas of your dog or your cat’s brain are affected, they are called psychomotor seizure (e.g. hallucinations). In humans, this form of seizure is called frontal lobe epilepsy. During these periods of altered 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 that you will see. Some pets hear imaginary noises. Your pet might bite or snap at you if you disturb it during one of those episodes. It might snap at imaginary flies. 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. Because so many different areas of your pet’s brain give rise to seizures, no two pets are likely to exhibit exactly the same signs or the same behaviors.
When Will Its Next Seizure Occur?
In some fortunate pets, seizures will be a one-time episode – never to occur again. In others, the problem reoccurs at regular intervals – from every several days to only a few times a year. Common traditional medications (such as phenobarbital) used to treat epilepsy can damage your pet’s liver over time. Only you, not your veterinarian, needs to decide if the number and severity of seizures your pet experiences, justify the risks of continuous, lifetime administration of medications.
Seizure Stages
Epilepsy can be broken down into three distinct stages. It is an ancient disease, written about since writing was invented, so it has been divided in many ways, with many confusing terms, with disagreements and overlap.
The first stage is called the prodromal or warning stage. It usually lasts a few minutes, but it can last much longer. Your dog or your cat’s mood and behavior changes. It might appear anxious. Common signs are restlessness, wandering, pacing, licking, trembling and vomiting.
The next stage is called the ictus or ictal stage. That is the time of the seizure event itself when your pet’s body is involved in uncontrollable movements and thrashing caused by the electrical “storm” occurring in its brain. In a complete seizure, during this stage your pet is unconscious. Paddling or swimming movements, clenched teeth, and an arched back are common. In partial seizures your pet may run in circles, or appear blind or deaf.
The final stage of an epileptic seizure is the postictal stage. This is the stage of gradual recovery. Dogs and cats in the postictal stage usually appear dazed or hung over. They might still bump into objects. They are exhausted, and tend to sleep or rest until fully recovered. They might have a blank contemplative expression or appear to just be staring out into space.
What Tests Can My Veterinarian Run To Confirm Epilepsy?
After a thorough physical examination, your veterinarian will want to begin with a complete blood chemistry panel as well as an analysis of your pet’s urine (urinalysis). If your pet is young or in early midlife and epileptic, these tests will probably all come back as normal. Even if your veterinarian is reasonably certain of the diagnosis at that point, he/she might suggest that you wait to see if the seizures return or perhaps begin your pet on anti-epileptic medications immediately. Your dog or cat’s T4 thyroid hormone test might then be low if your pet is already taking phenobarbital. (read here) I always suggest waiting until a repeat seizure pattern is established unless you, the pet’s owner, demands otherwise. When the seizures are multiple, severe or lengthy and the diagnosis remains uncertain, your veterinarian might suggest more specialized tests. Those include an MRI, CT scan or even a cerebrospinal fluid tap performed by a specialist.
What Should I Do During My Pet’s Seizure?
When a first seizure event occurs, pet owners tend to rush to an emergency veterinary hospital. 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. Also prolonged seizures are life-threatening and need to be “broken” with diazepam (Valium®) or a similar injectable drug. Luckily, most epileptic seizures last only a few minutes. One to three minute seizures are the most common. Those that last five to ten minutes are less common and much more serious. I have never seen a dog that “swallowed its tongue” during a seizure. Do not put your hand or fingers in its mouth. During prolonged seizures, 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. The exceptions are the breeds with short, deformed faces (e.g. bulldogs). They spend their entire lives with borderline respiratory passage obstruction. In those pets, seizure are considerably more life-threatening.
If you have a pet who experiences long seizures, ask your veterinarian to provide you with an emergency vial of diazepam or similar drug. None should be given by mouth to a seizuring pet. The standard injectable diazepam vial instructs you to give the medication by intravenous or intramuscular injection. Most pet owners would not be capable of that. But the drug can be placed up the pet’s rectum where it is also quickly absorbed. Your vet or their nurse 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. Again, give nothing by mouth to a seizuring dog or cat.
I am always concern that you are not 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 can then carry smaller pets to a secluded tiled area. For heavier dogs, it will take several people and a blanket, or roll the dog onto the blanket and slide gently slide it. Seizuring dogs are prone to overheat and need to be out of the sun. Remove all objects that surround your pet, so it does not injure itself. Keep the room darkened, cool and keep your other family members away.
How Soon Should I Think About Long-Term Medications?
That is a difficult question to answer. After your pet’s initial workup, I generally suggest that dogs and cats receive anti-seizure medications if they have had two or more seizures within an 8-10 week period – earlier if they were cluster seizures (major repetitive seizures). Dogs and cats that show unusually severe ictal or postictal periods should probably begin their medications sooner with standard doses and receive periodic dose and medication reevaluation thereafter. When seizures are rare, how frequently, if ever, that you and your family can tolerate the sight of a seizure is a major deciding factor.
What Medications Are Available?
Veterinarians have a long experience in using phenobarbital and potassium bromide in pets. But only a few limited studies have been performed regarding the long-term use of the newer human products in dogs and cats. (read here) 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. (read here)
Phenobarbital (aka Phenobarbitone)
Phenobarbital was the most commonly used drug to treat epilepsy in dogs and cats. The second most common treatment was phenobarbital combined with potassium bromide. Phenobarbital is still in common use in dogs and cats with epilepsy today. However, potassium bromide causes a high incidence of side effects in cats. In cats, it is only dispensed when no other options exist. But the addition or substitution of more recent medications that are dispensed to human epileptics is making their sole use less common. Your pet’s ideal phenobarbital dose is best determined through measurement of its blood serum phenobarbital level after it has been on a trial dose of the drug for some time, and periodically, thereafter. Phenobarbital can have negative effects on your pet’s liver. That is why liver function tests (including bile acids) are desirable 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 adjust to the medications. When side effects are significant, they 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. Cats do not seem as prone as dogs do to liver issues while on this drug, but they do tend to gain weight. Some veterinarians suggest giving epileptic pets milk thistle as a liver protectant while on phenobarbital.
Potassium Bromide
Combining phenobarbital with a second drug, potassium bromide, might lessen the chances of liver issues by permitting a lower phenobarbital dose. Dogs taking potassium bromide (KBr) should take it with food. Dog owners need to be careful with the salt level in their pet’s diet and or when the brand of dog food is changed. Higher salt diets and salty treats can decrease the level of KBr in the body. (read here) Their T4 levels and serum bromide blood concentration need to be periodically monitored. (read here) The most common side effects of this drug are behavioral changes, muscular twitching and a staggered gait. Potassium bromide occasionally produces other side effects. (ask me for Baird-Heinz2012) Most veterinarians rely on phenobarbital to get your pet’s seizures under control and then add potassium bromide as a second line defense to keep your pet’s phenobarbital dose as low as possible. Potassium bromide is rarely effective alone.
Primidone (Mysoline®, Mylepsin®, etc.)
The effects and side effects of primidone are the same as those of phenobarbital. That is because the majority of primidone is converted to phenobarbital in your pet’s body. In most studies, primidone was a bit less effective 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 makers, Boehringer Ingelheim Vetmedica, offered 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 which medications to 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)
Your veterinarian might give your pet an injection of diazepam, to end “break” a long-lasting seizure until other medications can take over for long-term seizure control. In dogs and cats, diazepam is quite successful in ending persistent, dangerous seizure. But when diazepam is given over longer periods of time, the body becomes resistant to its effects. Oral diazepam can be an effective “add-on” medication for epileptic cats because the positive effects of maintenance doses of diazepam seem to persist longer in feline than canine patients. In tablet form, it is quite bitter.
The Newer Medications
Levetiracetam (Keppra®)
Levetiracetam is an anti-epileptic drug developed for humans. Veterinarians sometimes use this drug in dogs in combination with phenobarbital and potassium bromide (KBR) to lower your pet’s daily phenobarbital and/or KBR requirement. It is also given in cases where phenobarbital and potassium bromide are unable 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 when given alone. (read here) But another study found that it was occasionally effective alone (monotherapy). (read here) A major drawback to levetiracetam is that the medication has a short half-life; so you have to give it to your pet several times a day. Rare side effects in dogs include a stiff wobbly gait, vomiting and salivation. Levetiracetam does appear to be an effective add-on medication for epileptic cats as well. (read here) It also appears that this medicine, when formulated as a cream, is effective in cats when applied to the inner surface of your cat’s ear. (read here)
Zonisamide (Zonegran®)
Zonisamide is sometimes effective in blocking epileptic seizures in dogs and cats. It does have a few common side effects that we know of. If they occur they are generally mild (e.g. 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 you, 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 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?
If the diagnosis is common epilepsy, probably not. Adding secondary medications that keep your pet as functionally normal as possible at the lowest possible doses is always a good plan. All changes should 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.
Very few truly epileptic dogs and cats cure themselves and stay seizure-free without medication. But it probably does occasionally happen. It does in humans. (read here) We veterinarians all make mistakes. Some of the dogs and cats that were put on long-term phenobarbital and other medications because they had a few seizures, with incomplete laboratory and physical work ups, and no family history of the problem, probably didn’t need medications at all. Don’t get your hopes up, but try changing your pet’s diet. (read here) If that helps, let me know. I have a client in which that appears to be working, going on six months now. Previously, his dog had one or more seizures every month. That client did not agree to give medications.
There is some evidence that in humans, diets high in fat and low in carbohydrate might be beneficial. (read here) Purina’s NeuroCare™ could conceivably be helpful. Unfortunately, Purina never released data that show its effectiveness in controlling epilepsy or forgetfulness. But you can give it a try. (read here) If you do, let me know what results you observe.
Will Idiopathic Epilepsy Shorten My Pet’s Life?
Probably Not. The median lifespan of dogs with idiopathic epilepsy was found to be 13.5 years. (read here)
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