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Phenobarbital for Dogs: A Definitive Guide

Your four-legged family member means the world to you. Trust us, we get it. At Honest Paws, we are all pet owners and animal lovers. Therefore, we know first hand how impossibly challenging it can be when something is wrong with (wo)man's best friend. Even worse, is experiencing it right before your eyes and knowing there is very little you can do. We're talking about dogs with epilepsy and seizures.

The first time your dog experiences a convulsion will undoubtedly be an incredibly difficult thing to experience. However, once it's over, the reality of the situation must be addressed. What to do now? There are several extremely important things to know about dog seizures and the associated medication used to treat them. Being armed with knowledge about the potential risks involved is imperative before beginning treatment.

In this article, we'll cover a popular medication used to treat seizures and epilepsy called phenobarbital. The realities of the drug may surprise you and will likely force you to reconsider whether the risks are worth the reward. We will also explore alternatives to the drug and ways that you can ensure Fido lives a long and happy life, regardless of their epilepsy diagnosis. Let's begin.

phenobarbital for dogs 

Understanding Dog Seizures

Before we jump into discussing all there is to know about phenobarbital, it is important to understand your dog's disorder. Studies show that up to 5% of all dogs suffer from seizures, yet so many owners don't completely know what having an epileptic dog entails. During the postictal phase after a seizure, the pet may also exhibit signs of disorientation, pacing, ataxia, and possible blindness.

Epilepsy is a term used to describe repeated episodes of seizures.

What Causes Seizures in Dogs

Many pet parents wonder if and how they can prevent seizures and epilepsy from developing in the first place. Was it something they could have stopped? The truth is, the majority of seizure disorders are referred to as idiopathic epilepsy. An inherited condition, idiopathic epilepsy is one in which experts are still unsure of the exact cause and origin. It’s a diagnosis of exclusion of other causes for seizures.  The majority of dogs diagnosed with idiopathic epilepsy are between 1 to 5 years old.

In other cases, seizures may develop due to the following conditions:

  • Liver disease
  • Kidney failure
  • Brain trauma
  • Brain tumor
  • Anemia
  •  Infectious diseases
  • Low or high blood sugar
  • Electrolyte problems
  • Stoke
  • Toxins (such as poisoning)

Diagnostics such as bloodwork, radiographs, ultrasound and MRI scans will be needed to determine the underlying cause of the seizure. 

Breeds Prone to Seizures

While seizures can occur in any dog, certain breeds are at a higher risk of the disorder.

Some common breeds include:

  • Basset Hound
  • Beagle
  • Belgian Tervuren
  • Collie 
  • Cocker Spaniel  
  • Golden Retriever
  • Keeshond 
  • Labrador Retriever
  • Schnauzer 
  • Shetland Sheepdog

It is extremely important for pet owners to be aware of risks associated with their dog's specific breed. For instance, Great Danes are at higher risks of heart disease and Boston Terriers are more prone to developing glaucoma. Knowing whether or not your dog is at a higher risk of any disorder will ensure that you know the beginning signs of development and can help prevent it from worsening.

What To Do For An Epileptic Dog

When your dog is experiencing a seizure, one of the most important things that you can do is make their surroundings as calm and quiet as possible. Also make sure that your pet is safe and away from any potential hazards. Never place your hands near the mouth of a seizing dog as they are unconscious and can bite Seizures do not cause the dog any pain, but loud noises, bright lights, and stress can cause the seizure to worsen as well as cause additional episodes to occur. 

We also want to mention that as your dog's seizure can be frightening for you to watch, it is equally as troubling for other pets in the house. It is important to make sure that any other pets are kept away from the animal experiencing the seizure as additional barking can stress the dog out and cause more seizures to occur.

When to Begin Anti-seizure Medications

According to the American College of Veterinary Internal medicine, therapy should be started for any dog that fits into one of the following categories:

  • Cluster seizures or more than 3 seizures in a 24 hour
  • If the seizure lasts longer than 5 minutes
  • If the seizure or post-ictal phase is severe
  • If the dog has a history of a brain injury or trauma
  • If there is a visible brain lesion on advanced imaging (such as MRI)
  • Breeds that are known to have difficult seizure control (Australian shepherds, Border collies, German Shepherds, Golden retrievers, Irish setters and Saint Bernards)

What is Phenobarbital for Dogs

Now, let's get back on track: Phenobarbital for dogs.

Phenobarbital for dogs is one of the most commonly prescribed medications to control the frequency and severity of seizures and epilepsy. It is a widely utilized first choice anti-seizure medication as it is effective, easily dosed and reasonably priced. The drug is more widely known by its generic name, but also available in several brand names such as Luminal or Barbita. Phenobarbital can either be used alone or in conjunction with other drugs to better treat epilepsy in dogs. It is available in several different size capsules, tablets, oral liquid, or injectable (for emergencies) forms.

phenobarbital for dogs vs potassium bromide for dogs

Understanding How Phenobarbital for Dogs Works

A seizure occurs due to an unexpected surge in neuron activity in the brain. Phenobarbital works to minimize the severity and frequency of seizures by stabilizing and decreasing neuron activity within the brain. The drug also decreases the neurotransmitter (known as glutamate), which is responsible for nerve stimulation.

Phenobarbital Uses

Many conventional drugs serve a wide array of purposes and treat varying diseases all with the same pill. Phenobarbital, however, is primarily only used to treat seizures and epilepsy. In some (relatively) uncommon cases, phenobarbital may be used as a sedative.

Dosage Of Phenobarbital For Dogs

The appropriate dosage of Phenobarbital will significantly vary among different breeds of dogs. It is imperative that your veterinarian decides on the accurate dose after considering your dog's weight, the severity of the seizures, and how often they occur.

In most cases, your vet will direct you to administer Phenobarbital every 12 hours. Typically, the starting dose of Phenobarbital for dogs is around 1 mg per pound of bodyweight.  With all drugs, but particularly with Phenobarbital, it is extremely important that you do not miss a dose as it can cause your dog to have a severe seizure episode. If for any reason you do miss a dose, NEVER double up on the next dose. Give your dog the missed dose as soon as possible and then carry on with the usual routine of another dose every 12 hours.

Phenobarbital Precautions

Before we get into the side effects associated with phenobarbital, there are a number of dogs who shouldn't be taking it in the first place. It is imperative that your veterinarian knows absolutely everything when it comes to your dog's health and history in order to know whether or not Phenobarbital is an appropriate medication.

Dogs Who Should NOT Take Phenobarbital

If your dog has any of the following health conditions, they should not take phenobarbital:

Additionally, the following medications have been shown to have drug interactions with phenobarbital.

  • Antihistamines
  • Anticoagulants
  • Beta-adrenergic blocker
  • Corticosteroids
  • Diazepam (along with other central nervous system depressants)
  • Doxycycline
  • Furosemide
  • Griseofulvin
  • Metronidazole
  • Rifampin
  • Theophylline
  • Valproic acid
  • Phenytoin sodium
  • Opiate agonists
  • Phenothiazine
  • Aminophylline
  • Chloramphenicol
  • Quinidine

Phenobarbital Side Effects in Dogs

The aforementioned precautions associated with phenobarbital are enough to make anyone want to learn more about this popular medication. However, they aren't the only concerns associated with the drug. The following are the common side effects of phenobarbital for dogs.

Excessive Hunger & Weight Gain

A side effect of phenobarbital for dogs that many pet parents have found is excessive hunger. Subsequently, all of the extra food intake can often lead to weight gain, particularly if the medication also alters their normal amount of activity.

phenobarbital for dogs can cause weight gain

Excessive Thirst & Urination

Another common side effect of phenobarbital is excessive thirst and therefore an increased need to go to the bathroom. If you notice that your pup is frequently needing water bowl refills, it's likely a side effect of the medication.

Anxiety

Phenobarbital can also cause your dog to feel high levels of anxiety and uneasiness. As we touched on, anxiety is the enemy of dogs suffering from seizures and epilepsy as it can cause their seizures to worsen and occur more often.

Ataxia

The medication can also cause the dog to lose coordination in the hind limbs as well as experience bouts of weakness which inhibit their ability to move freely. This can be seen when initially starting the medication but it generally improves over time. 

Depression

Like people, dogs can also experience bouts of depression. If you notice your dog sleeping more than usual or appearing down in the dumps, the medication may be at fault.

Lethargy

Similar to the symptoms of depression, the medication can also cause the dog to be very lethargic and appear to have no interest in things they once enjoyed. This side effect is generally transient in nature. However, it may also be a sign that the dosage is too high for your pet.

Hyperexcitability

Conversely, while some dogs experience high levels of lethargy, some experience the exact opposite: hyperexcitability or agitation. If you find your dog pacing nonstop, acting restless, panting without reason, or being especially vocal, it's likely a side effect of Phenobarbital.

Liver Damage & Liver Failure/Toxicity

Long-term use of phenobarbital has been directly linked to liver damage, including scarring in the liver and liver failure. Liver toxicity is also associated with prolonged high phenobarbital levels. It is very important to have your pet’s phenobarbital levels and liver values monitored during therapy. Signs of toxicity, liver damage, and/or liver failure include:

  •     Anorexia/Loss of appetite
  •     Vomiting
  •     Diarrhea and stool changes
  •     Weight loss
  •     Jaundice (yellow coloring of skin and mucous membranes)
  •     Lethargy

Anemia

Lastly, in rare cases, phenobarbital has caused anemia to develop. Signs of anemia include pale gums and lethargy. If for any reason you feel that the medication has caused the development of another disease, contact your vet.

Lessening the Side Effects of Phenobarbital

As you can see, the side effects of Phenobarbital can be pretty terrible. Therefore, minimizing any side effects that you can is paramount for your dog's health and wellbeing. The best way to do this is to ensure that your vet prescribes the lowest viable dose possible.

Additionally, it is beyond important for pet owners to have a heightened awareness of the aforementioned side effects. Recognizing a side effect when it first appears and acting appropriately is key to preventing irreversible damage.

While your pet is on phenobarbital it is important to follow your veterinarian’s recommendations for monitoring. Phenobarbital levels are checked after starting the medication to make sure your pet is on an appropriate dosage and then every 6-12 months thereafter. The levels should also be rechecked if there is an increased frequency of seizures or anytime the dose is adjusted.  In addition, your pet’s liver values should also be monitored at the same frequency to catch any early liver changes before they become significant. 

Anti Seizure Medication Produces Additional Seizures

Unfortunately, you read that correctly. A major cause of seizures in dogs is the build-up of chemicals and toxicity in the body. The long-term use of anti-seizure medications can flood the body with more toxins than it is able to flush out. On top of that, once the kidney or liver become damaged, even less toxins are able to be passed through the body. Hepatic encephalopathy is a condition that can be seen with severe liver disease. Seizures can then develop due to impaired liver function.

On the other end, stopping the anti-seizure medication can also lead to the development of additional seizures, some which can be life-threatening. For this reason, it is imperative that dog owners understand the risks involved with beginning an anticonvulsant medication.

phenobarbital for dogs is best avoided

Alternatives for Phenobarbital for Dogs

Now, thankfully there are new conventional, anticonvulsant drugs as well as all-natural alternatives for Phenobarbital for dogs. Before we dive into the options available, we want to stress that by no means are we trying to negate the need for conventional medicine. Some dogs in specific circumstances need Phenobarbital and we know that to be true. However, the medication is being prescribed at an exorbitant rate, many times to pet owners who do not fully understand the risk. The information we just discussed is not to scare you, but to make sure you are informed before making a decision.

Potassium Bromide

Potassium bromide is another older commonly prescribed drug that aims to reduce the severity and frequency of seizures. Often times, veterinarians will prescribe both potassium bromide and phenobarbital to be used together. In other cases, particularly in dogs who have a drug-resistance or in those who do not react will to phenobarbital, potassium bromide will be prescribed as a replacement.

There is only one FDA approved form of potassium bromide (K-BroVet), otherwise it can also be compounded through an approved pharmacy. Side effects may include nausea (which may improve by giving the medication with food), increased drinking and urination and drowsiness. Bromide levels also need to be monitored as a toxicity syndrome can be seen if the blood levels get too high. It can take months for the medication to reach a steady therapeutic blood level, so an additional anti-seizure medication may be needed in the beginning.

Levetiracetam (Keppra) 

Levetiracetam (Keppra) is a newer anticonvulsant medication that is now being prescribed to epileptic dogs. Keppra can be used alone or in conjunction with other anticonvulsant drugs. Many pet owners are eager to try the new medication as it allows for a decreased dosage of Phenobarbital and therefore a decreased amount of adverse effects. However, there are still certain risks and potential adverse effects associated with Keppra for dogs including drowsiness, lethargy, behavioral changes, and gastrointestinal upset. 

The main disadvantage of Keppra is that it usually has to be dosed three times a day for most patients. This means more potential for missed doses and an increase in seizures. There is an extended release formula that can be given twice daily but the tablets cannot be cut, thus it may not be a viable option for smaller pets. Tolerance can also be seen when used long term. In addition, patients with kidney disease may need a dose adjustment.

Zonisamide (Zonegran)

Zonisamide is also a newer anti-seizure drug being used in dogs. It is usually prescribed at twice a day and there are blood levels that can be monitored. The starting dose for zonisamide is usually higher for dogs that are also receiving phenobarbital.  The most common side effects include sedation, vomiting and diarrhea. 

The Power of Food

Additionally, we want to make sure that our readers never overlook the immense power that diet can have for our pets. For centuries and centuries, food has been used to cure and prevent a number of ailments. While science has certainly progressed, the fact of the matter is, food is still some of the best medicine available. Countless studies prove that a specifically formulated diet can be an absolute game-changer for an epileptic dog. Many experts advocate for a ketogenic diet, or one that is high in fats and low in carbohydrates. 

A new veterinary therapeutic diet from Purina uses medium chain triglycerides (MCTs) as the fat source, which can add to increased seizure control in conjunction to mediations.  One can also contract a board certified veterinary nutritionist to help formulate a home-cooked diet as another option. Remarkably, a simple dietary change has been shown to significantly reduce the severity and frequency of seizures in dogs.

Also, diet is also essential for dogs that are presently being treated with conventional anti-seizure medications. We discussed that these drugs are directly tied to kidney damage. Therefore, an exceptionally balanced diet will be paramount in ensuring that the body has enough support to help rebuild and protect the organ from additional damage occurring.

Acupuncture

Finally, experts have found that the use of Chinese medicine such as acupuncture can have positive effects for dogs (and people) suffering from epilepsy. Keeping that in mind, acupuncture works best with strict consistency and may not be an appropriate match for everyone's lifestyle. Either way, the fact that so many pet owners are seeing benefits from alternative healing is something that we can all be grateful for.

Knowledge is Power 

The last thing that we want to mention is the importance of staying aware of new breakthroughs in pet wellness. For instance, new studies have found that several flea and tick medications are directly linked to an increase in seizure activity in epileptic dogs. Knowing all there is to know about your dog's condition and how to prevent it from worsening can truly affect your dog's wellbeing and make a difference in their quality of life.

Phenobarbital for Dogs: The Bottom Line

When all is said and done, we know that you want the very best for your beloved four-legged family member. With the constant advancements in both conventional and holistic medicine, we truly feel that owners of epileptic dogs have a number of safe, effective options available to them. With that said, as a pet owner, you must ensure that you are doing everything you can to understand your dog's condition and make educated decisions for their wellbeing. In many cases, this may mean forgoing the use of a drug such as Phenobarbital.

Sources 

https://simplewag.com/dog-seizures/

https://www.honestpaws.com/blogs/pet-care/dog-seizures

https://vet.osu.edu/vmc/companion/our-services/neurology-and-neurosurgery/more-epilepsy

https://www.thesprucepets.com/zonisamide-for-treating-seizures-pets-3384742

https://veterinarypartner.vin.com/default.aspx?pid=19239&id=4951440

 https://veterinarypartner.vin.com/default.aspx?pid=19239&id=4951497

Jennifer Dempsey, DVM

Dr. Jennifer Dempsey is a small animal veterinarian and freelance medical writer. She received her Bachelor of Science from the University of Central Florida and her Doctorate of Veterinary Medicine from the University of Florida (Go Gators!) 

She has resided in the Orlando area since graduation and has gained years of experience helping cats and dogs live happier and longer lives. As a general practitioner, she has found client education to be one of the most important aspects of day to day life in veterinary medicine.  

Medical writing has helped her to connect with a larger audience and make sure that pet owners are fully aware of their loved one’s medical condition.  She currently shares her home with two rescued mixed breed dogs named Primo and Morgan.

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