Managing Idiopathic Epilepsy in Dogs

Idiopathic epilepsy in dogs can be managed with one or more anticonvulsants, including phenobarbital, zonisamide, and levetiracetam. Learn more about the potential side effects of these medications and about other ways to manage seizures in dogs.

By
Dr. Jennifer Bailey
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Idiopathic epilepsy in dogs is a difficult but manageable condition.
Managing idiopathic epilepsy in dogs can be challenging but there are a number of therapies available. Credit: THEPALMER | Getty Images

Seizures in dogs can have several different triggers or causes. When no trigger or cause for seizure activity is found, then a dog is presumed to have idiopathic epilepsy.

 

 

 

Diagnosing Idiopathic Epilepsy in Dogs

Idiopathic epilepsy affects young dogs between the ages of six months and six years. As the name implies, the cause of idiopathic epilepsy is unknown. It is a diagnosis of exclusion, meaning that other causes of seizures must be ruled out before making this diagnosis.

Any breed of dog can be affected by idiopathic epilepsy. However, it is diagnosed more often in Schnauzers, Collies, Basset Hounds, Cocker Spaniels, Labrador Retrievers, and Golden Retrievers.

If your dog is experiencing seizures, have your dog assessed by a veterinarian as soon as possible. Your veterinarian will want to complete blood work, a urinalysis, and x-rays of the chest and abdomen. She may also want to check your dog’s blood pressure and order additional tests based on what she finds on the initial diagnostics. Your dog may be referred to a veterinary neurologist for an MRI of his brain if a cause for his seizures cannot be found.

When To See a Veterinary Neurologist

Your veterinarian may recommend a consultation with a veterinary neurologist if initial diagnostics do not reveal an underlying cause of your dog’s seizures. Most people think of an expensive consultation when they hear the words “veterinary specialist.” But having a veterinarian that specializes in neurology on your team can make a huge difference in your dog’s seizure management.

A consultation with a veterinary neurologist typically costs between $200 and $300. During this consultation, your dog’s complete health and seizure history will be reviewed. Your dog will receive a complete neurologic examination. An MRI and obtaining a sample of cerebrospinal fluid (CSF) for tests may be recommended.

You do not have to follow through with completing advanced diagnostics if they are cost prohibitive. You and your dog will still benefit from advice provided by the veterinary neurologist. Veterinary neurologists are specialists who have completed an internship and residency in neurology and are board-certified in their field. They keep up to date on the latest research and advancements in treating idiopathic epilepsy.

You and your veterinarian may consult with your veterinary neurologist for up to one year following the initial consultation. Most veterinary neurologists are available by email or by phone to answer questions about managing your dog’s seizures. They can provide advice on anticonvulsant dose adjustments, adding anticonvulsants, and alternative therapies that may help your dog live a better quality of life.

Keeping your veterinary neurologist a part of your dog’s medical team will require an annual recheck examination. This maintains a valid veterinary-client-patient relationship (VCPR) and enables you and your veterinarian to continue seeking advice on how to manage your dog’s seizures.

Anticonvulsant Medications for Dogs

Idiopathic epilepsy is often managed with one or more anticonvulsant medications. These medications are given for the remainder of a dog’s life and can have long-term side effects. The decision to start anticonvulsants should be made according to your dog’s specific situation.

You should consider starting your dog on an anticonvulsant if he meets one or more of the following criteria:

  • He is having cluster seizures. This is two or more seizures in a 24-hour period.
  • He has more than one seizure per month.
  • He is having seizures that last five minutes or longer.
  • His seizures are violent and there is danger that he may hurt himself during a seizure.
  • He is a breed that is known to have seizures that are difficult to manage. These breeds include German Shepherds, Border Collies, Irish Setters, Golden Retrievers, Siberian Huskies, Keeshonds, and Saint Bernards.

Dogs that need their idiopathic epilepsy medically managed will be started on one of four primary anticonvulsants: phenobarbital, zonisamide, potassium bromide, or levetiracetam. Your veterinarian may recommend baseline blood work to check your dog’s liver enzymes, kidney values, and thyroid function before starting an anticonvulsant. A complete blood count (CBC) and chemistry panel should be completed at least every six months while taking any anticonvulsants.

There is no right or wrong primary anticonvulsant to start with for managing seizures in dogs. Factors that may influence medication selection include cost, dosing frequency, dosage form (such as liquid, capsule, or tablet), size available for your dog’s weight and your dog’s tolerance of side effects. Your veterinarian’s experience and comfort level with each anticonvulsant may also influence the drug selection.

Your veterinarian will recommend obtaining your dog’s therapeutic level of the anticonvulsant selected after he has started medication therapy. This is a blood test that examines the concentration of anticonvulsant in your dog’s bloodstream. The timing and frequency of testing will vary depending on the medication selected and how well-managed your dog’s seizures have become.

Phenobarbital

Phenobarbital has the longest history of use amongst the selection of anticonvulsants. It is typically administered twice a day although once a day dosing may be sufficient to achieve seizure control in some dogs. Phenobarbital is a controlled substance that is available as a tablet. It must be filled by your dog’s veterinary hospital or be accompanied by a written prescription if filled by an outside pharmacy.

Side effects of phenobarbital include sedation, increased thirst and urination, and ataxia (wobbly gait). These side effects are typically transient and spontaneously resolve within the first 1-2 weeks of starting phenobarbital. There are some dogs for whom these side effects may not resolve unless phenobarbital is discontinued.

Dogs receiving high doses of phenobarbital are at increased risk of developing liver damage. Other side effects of phenobarbital are rare but serious. These include a low platelet count, a low white blood cell count, and anemia (low number of red blood cells). Development of hepatocutaneous syndrome is a rare reported side of phenobarbital.

Your dog’s phenobarbital therapeutic level should be checked two weeks after starting this medication. It should also be checked two weeks after any change in your dog’s phenobarbital dose. The phenobarbital level in your dog should be kept below 35 mcg/mL (micrograms per milliliter) to minimize the risk of liver damage.

Zonisamide

Zonisamide is a newer anticonvulsant that has grown in popularity as an initial drug for managing idiopathic epilepsy in dogs. This medication is administered twice a day. It is only available as a capsule.

Side effects of zonisamide include sedation, ataxia, and decreased appetite. These side effects are typically transient and spontaneously resolve within the first 1-2 weeks of starting zonisamide.

Other potential side effects of zonisamide are rare but serious. These include a low platelet count, a low white blood cell count, and anemia. Liver and kidney damage may also occur.

Your dog’s zonisamide therapeutic level should be checked two weeks after starting this medication. It should also be checked two weeks after any change in your dog’s zonisamide dose.

Potassium Bromide

Potassium bromide was the first anticonvulsant prescribed for people and dates back to 1857. It is available as a flavored chewable tablet and as a flavored oral solution for dogs. This medication can be administered once a day.

It can take up to three months for potassium bromide to reach a therapeutic level in your dog when using a standard daily dose. Your veterinarian may prescribe an initial loading dose regimen for your dog to achieve a therapeutic level in a shorter period of time.

Side effects of potassium bromide include increased appetite, increased thirst and urination, weight gain, sedation, and vomiting. These side effects are typically transient and spontaneously resolve within the first 60 days of starting potassium bromide. Long-term side effects may include increased risk of developing pancreatitis or megaesophagus. Rarely, dogs may experience increased aggression when taking potassium bromide.

Potassium bromide is not metabolized in a dog’s body and is excreted unchanged in the urine. This medication should be used cautiously in dogs with kidney disease. Taking potassium bromide may complicate management of diseases that alter electrolyte balance, such as gastroenteritis and hypoadrenocorticism (Addison’s disease). Talk to your veterinarian before making changes to your dog’s diet while taking potassium bromide. Avoid giving your dog salty foods while taking this medication.

Your dog’s potassium bromide therapeutic level should be checked at three weeks and at three months after starting this medication. Dogs that have received a loading dose of potassium bromide should also have their therapeutic level checked the day after receiving the last loading dose. Comparison of therapeutic levels the day after the last loading dose has been administered and at the three-week mark may predict what your dog’s therapeutic level will be after three months of therapy.

Levetiracetam (Keppra)

Levetiracetam (more commonly known by its brand name, Keppra) is an anticonvulsant that is well-tolerated in dogs and has relatively few side effects. Keppra may protect the brain from damage that can be caused by seizure activity.

Keppra is available as a tablet. Tablets are available in two forms—standard release and extended release. Standard release tablets are administered three times a day. Extended release tablets are administered twice a day. Extended release tablets have a special coating that slows absorption of the drug in the gastrointestinal tract. These tablets cannot be crushed, split, or chewed.

Side effects of Keppra are mild and may include sedation, ataxia, and vomiting. These side effects—if they occur—typically resolve after lowering the dose of Keppra. Keppra has a wide margin of safety in dogs and monitoring of therapeutic levels is not necessary.

Using Multiple Anticonvulsants for Dogs

Most dogs will experience a decrease in the frequency and duration of seizures after starting one of these four primary anticonvulsants. Some dogs may need to take two or more primary anticonvulsants to achieve control of their seizures.

Phenobarbital alters the metabolism of zonisamide and Keppra. Dogs that are taking phenobarbital with zonisamide or Keppra will need to be prescribed a higher dose of these medications.

Adjunctive Anticonvulsants

Refractory epilepsy is when a dog’s seizures are not well-managed on two or more primary anticonvulsants. Adding an adjunctive anticonvulsant may help these dogs achieve better control of their seizures. Adjunctive anticonvulsants include gabapentin, pregabalin, felbamate, topiramate, and clonazepam.

Gabapentin and Pregabalin

Gabapentin and pregabalin have a similar mechanism of action on nerve synapses in the brain. These medications are also used for their analgesic and anxiolytic (anti-anxiety) effects in dogs. Side effects are few and may include sedation and ataxia. These medications are given two to three times daily. Monitoring of therapeutic levels is not necessary.

Gabapentin is available as a tablet, capsule, and an oral solution. Some gabapentin oral solutions contain xylitol; these should not be given to dogs. Pregabalin is a controlled substance that is available as a capsule and an oral solution. It must be filled by your dog’s veterinary hospital or be accompanied by a written prescription if filled by an outside pharmacy.

Felbamate

Felbamate has been shown to be an effective adjunctive anticonvulsant in some dogs that have refractory epilepsy. Side effects are rare and include liver damage, generalized tremors, and keratoconjunctivitis sicca (dry eye). Other rare side effects include a low platelet count, low white blood cell count, and anemia (low number of red blood cells).

Felbamate is available as a tablet and an oral solution. This medication is given three times a day. Taking felbamate with phenobarbital may increase the concentration of phenobarbital in your dog’s blood. Your dog should have a complete blood count (CBC) and chemistry panel checked every six months while taking felbamate.

Topiramate

Topiramate may also help dogs with refractory epilepsy achieve better control of their seizures. Side effects include sedation, ataxia, and weight loss. Topiramate should be started at the low end of the dosing range and slowly increased to effect.

Topiramate is available as a tablet and an oral suspension. This medication is given three times a day. A chemistry panel should be completed every six months while taking topiramate.

Clonazepam

Clonazepam may be an effective adjunctive anticonvulsant for dogs that are already taking phenobarbital. Dogs may develop diarrhea when first starting this medication. Starting clonazepam at a low dose once a day and gradually increasing the dose may minimize the risk of developing diarrhea.

Clonazepam is available only as a tablet. This medication is given two to three times a day. Dogs may experience elevated liver enzymes after taking clonazepam for more than a few months. A chemistry panel should be completed every three to six months while taking clonazepam.

Pulse-Therapy for Cluster Seizures in Dogs

Dogs with idiopathic epilepsy may suddenly experience cluster seizures, even if their seizures are otherwise well-managed with one or more anticonvulsants. Cluster seizures are defined as having two or more seizures in a 24-hour period. Administering a pulse-therapy anticonvulsant may prevent further seizures in the cluster period.

Pulse-therapy anticonvulsants include clorazepate and Keppra. Either medication can be started after a dog begins experiencing cluster seizures. It is given three times a day until the dog has remained seizure-free for 24-48 hours. The typical length of treatment with a pulse-therapy anticonvulsant is three days.

Status Epilepticus and Rescue Anticonvulsants

Dogs that are experiencing a condition called status epilepticus may require administration of a rescue anticonvulsant. Status epilepticus is defined as:

  • Having a seizure that lasts longer than five minutes
  • One or more seizures in a five-minute period with no return to normal consciousness between seizures

Status epilepticus can quickly become a life-threatening condition. Dogs will experience the following symptoms in the first 30 minutes of status epilepticus:

  • Increased heart rate and blood pressure
  • Decreased oxygen delivery to vital organs
  • Increased body temperature, sometimes exceeding 108°F (normal temperature range for dogs is 99°F to 102.5°F)

The following symptoms may develop if status epilepticus continues for more than 30 minutes:

  • Neurogenic pulmonary edema. This is when fluid accumulates within lung tissue.
  • Heart muscle damage. This impairs the heart’s ability to contract and push blood to vital organs.
  • Acute kidney injury followed by acute renal failure.

Administration of a rescue anticonvulsant may interrupt status epilepticus but will likely not resolve it. Seek immediate veterinary care if your dog is experiencing status epilepticus.

Rescue anticonvulsants include diazepam and midazolam. Diazepam is administered rectally using a red rubber catheter. Midazolam is administered intranasally (in your dog’s nostril) using a special device called an atomizer. An atomizer is a small plastic device that converts liquid medication into a fine mist. The atomizer is attached to the end of a syringe containing a dose of midazolam and inserted into your dog’s nostril. Pushing the plunger on the end of the syringe delivers the midazolam dose to your dog.

Intranasal midazolam typically takes about one minute to stop your dog’s seizure. Rectal diazepam may take 3-5 minutes to stop seizure activity. Dogs that are experiencing status epilepticus may resume having seizures within 10 to 20 minutes. The most common side effects of diazepam and midazolam are sedation and ataxia.

Alternative Therapies for Managing Seizures in Dogs

Alternative therapies may help manage seizures in dogs already receiving one or more anticonvulsants. These therapies include cannabidiol (CBD), acupuncture, and a prescription neurologic diet.

Purina ProPlan Veterinary Diet NeuroCare (Purina NC diet) is a prescription diet specifically formulated to help reduce the frequency of seizures in dogs with idiopathic epilepsy. The component of the diet responsible for this phenomenon is medium chain triglyceride (MCT) oil. The Purina NC diet also includes several antioxidants to support overall brain health. Learn more at https://vetcenter.purina.es/neurocare/pdf/multicentrico.pdf.

CBD has recently been shown to reduce seizure frequency in epileptic dogs with refractory seizures. Dogs included in the research study published in the Journal of Veterinary Internal Medicine were on at least one anticonvulsant and having at least two seizures a month. Side effects of CBD include elevated liver enzymes, vomiting, and decreased appetite. Learn more at https://pubmed.ncbi.nlm.nih.gov/37889215/.

Navigating the realm of CBD supplements for dogs can be overwhelming. CBD products are not federally regulated and may include variable concentrations of CBD content or have contaminants, including heavy metals and tetrahydrocannabinol (THC). There is also little known about the appropriate therapeutic doses of CBD in dogs. Talk to your veterinarian about adding CBD to your dog’s anticonvulsant therapy before purchasing any CBD product.

Traditional Chinese Veterinary Medicine (TCVM) may be of benefit to some epileptic dogs suffering from refractory seizures. TCVM includes acupuncture and Chinese herbal supplements. Veterinary acupuncture is a specialized field. Ask your veterinarian about a referral to a veterinary acupuncturist who is skilled in helping dogs with idiopathic epilepsy.

Idiopathic epilepsy in dogs can be a challenging condition to manage. Thankfully, there are several therapeutic options available for epileptic dogs. Talk to your veterinarian about tailoring therapies to your dog’s specific needs.

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