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Rare Phenobarbital Side Effects in Dogs – One Dog’s Story

kartoffel treatment plan

Last Updated: May 24, 2024 by Lisa Melillo

Here Because Your Dog is Starting Phenobarbital?

This is a new section I’m adding due to an increase in new visitors searching for “phenobarbital side effects in dogs” that are just starting their dogs on Phenobarbital. When I originally wrote this article, I was writing for other dog owners who already had their dogs on Phenobarb, were experiencing unexplained health issues, and looking for answers.

I don’t want to scare anyone from following their vet’s orders and giving their dogs Phenobarb, so here’s a few important points if you are here because you’re having second thoughts about starting your dog on their prescription.

  • If your vet is prescribing Phenobarbital for seizures, you should use it. Yes, there are side effects and in some VERY RARE cases (like what occurred to my dog) they can be very serious. If you know the symptoms to look for though, you can prevent any serious damage from occurring.
  • Phenobarbital has been used in pets and humans for over 100 years. It’s widely established to be very safe and effective for the vast majority of cases. It’s also at least 10x cheaper than alternative seizure medications and much more commonly available.
  • CBD isn’t a replacement for Phenobarbital. There’s no evidence that CBD oil for dogs is a replacement for anti-seizure drugs. However, there is evidence that CBD used along with anti-seizure drugs such as Phenobarbital or Potassium Bromide results in fewer seizures.

With those points out of the way, let’s get back to the article.

TL;DR – if your dog is recently on phenobarbital and has symptoms such as a suppressed white blood cell count and autoimmune issues (something that looks like an allergic reaction) then phenobarbital may be the cause. Read on for more details of my story and check out the comments below for others.

Background on Phenobarb

Phenobarbital is a very common prescription drug used to control seizures in both humans and pets. It’s almost always the very first medication your vet will recommend if your dog is diagnosed with epilepsy, due to the very low cost of the prescription as well as it generally being viewed as a safe drug as it has been in use for over 100 years.

That being said, there are still very rare cases where phenobarbital has incredibly dangerous side effects to your pet, and unfortunately my dog, Kartoffel, suffered from side effects for months before we realized phenobarbital was the cause. In fact, it’s possible he could have needed a bone marrow transplant or even had to be put down if we waited much longer.

The purpose of this article is to share our story, because I wasn’t able to find anything like this documented online when I was looking for possible causes of Kartoffel’s health issues. To be clear though, this is NOT me making a case against phenobarbital or suggesting you don’t listen to your veterinarian. This is meant to be a list of things to watch out for if your dog is starting phenobarbital or has been on phenobarbital for some time, and is having strange, maybe seemingly unrelated health issues.

Part 1: Kartoffel Has Seizures

kartoffel laying
Kartoffel lounging around the time of his first seizure

This saga all starts back in June of 2017. As I was getting ready for bed, Kartoffel came upstairs and gave my wife a strange look seemingly knowing something was wrong. A few seconds later he collapsed to the ground and started have a seizure – his first ever, around 4 years of age.

After a frightening minute or so the seizure passed and Kartoffel exhibited amnesia after his seizure – something he has done after every seizure to date. This is something else I haven’t found any information on, so I’ll describe it a bit here in case it’s helpful to others.

After his seizures, he wakes back up and looks lost and scared. He clearly has no recognition in his eyes as to where he is or who we are. So he starts barking and isn’t too keen to let anyone near him! As a 110lb+ dog, this can be alarming it it’s own right though I’d say he doesn’t cross the line into aggression.

These amnesia episodes last anywhere from 30-90 minutes before he snaps back to himself. I haven’t found any surefire ways to get him to regain his memory faster, sometimes it seems like letting him sniff me works but not always. If you know of something that could help, let me know in the comments!

Moving on, after the first seizure we took him to the emergency vet, had bloodwork done and had him stay overnight in case he had more. At this point we weren’t sure if it was epilepsy, a brain tumor, something he ate, etc and other than an expensive brain scan there’s no good way to narrow down the possible cause other than to wait and see if it happens again.

Somewhere in the neighborhood of 8-10 weeks later, Kartoffel had another seizure. This time between seizures meant it’s very unlikely to be a brain tumor (good!) and very likely that it’s canine epilepsy (boo!).

So we got him started on phenobarbital sometime in mid to late August (as best I can remember), which hopefully would reduce his seizures to 2-4 times a year, or maybe even less. There’s no real “standard” for what kind of change you can expect from seizure medications, only that they should occur much less frequently than if left untreated.

Part 2: Unknown Phenobarbital Side Effects

It wasn’t too long after Kartoffel was on his daily dosages of phenobarbital that the side effects started coming. The first thing I can remember is that he started getting raised bumps on his snout. They were under the skin/fur, did not move, and were somewhat hard. We took Kartoffel to the vet to get looked at, and the diagnosis was it was some sort of allergic reaction. Possibly to something he got into outside, flowers/trees, etc.

He was given a cortisone shot which would suppress his immune system response (this is an important trend) and the bumps went away shortly. If my memory is correct they may have came back once more, another shot was given, and they were not seen again before we got him off of phenobarbital.

Another issue he was having was a red, bulging left eyeball. It was like his eyeball was inflamed and reddened which he was also taken to the vet for and also diagnosed as some sort of allergic response. He got more cortisone, allergy pills, and eye drops but nothing seemed to truly fix the problem. This ended up being another strange side effect of what phenobarbital was doing to his immune system.

Part 3: Admission to the Emergency Hospital

kartoffel at emergency hospital

In mid to late November, things finally came to a breaking point. Kartoffel had been developing some weakness in his legs that we thought was part of the sedation of the phenobarbital, but one morning Kartoffel struggled to even stand and I knew something was very wrong. I made a same-day appointment for the vet and after observing his weakness they had a blood test done.

This is what was most shocking and really raised the alarm. A normal white blood cell count for a dog is between 6,000 to 17,000. Kartoffel’s white blood cell count was ~450 – lower than most dogs going through chemotherapy. This could only mean his immune system was having serious issues and basically not functioning. His bone marrow was not producing the white blood cells his body needed to fight infections and carry oxygen through his blood stream. His muscle weakness? Likely a lack of oxygen reaching the muscles.

I’m lucky enough to live within 15 minutes of a full-scale emergency veterinary hospital complete with an internal medicine and neurology department, so I left my regular vet and took him in to be admitted.

After talking with an internal medicine specialist, she determined that the phenobarbital could be the culprit. It seems the drug was somehow toxic to his body and damaging his bone marrow, or preventing it from functioning properly. We had to get a bone marrow biopsy done on him, which involved putting him under anesthesia and taking a sample from a bone in his shoulder.

The biopsy results came back and determined that his bone marrow looked “different” but still functional, which was great news and also seemed to confirm the new diagnosis. The new treatment plan was as follows –

  • Ween Kartoffel off of phenobarbital onto a new seizure medication (Potassium Bromide)
  • Keep Kartoffel on some serious doses of Prednisone for months (to suppress his immune system’s reaction from attacking his bone marrow/white blood cells)
  • Give Kartoffel antibiotics for several weeks as his body can’t fight off any infections with such a low white blood cell count.
  • A handful of other drugs I don’t remember the purpose of, see below!
kartoffel treatment plan

After 3 nights of being admitted to the hospital (total charges came to around $4,000 for this stay – I’ll be considering pet insurance for future dogs!), Kartoffel was released to us to come back home.

Part 4: The Aftermath and Today

I can’t remember the exact timeline of when Kartoffel completed his transition to the new medication and got off everything else, but eventually his blood cell count was back to normal and has remained normal since. After switching to Potassium Bromide he had two seizures about 10 weeks apart, but at the time of writing we’re on a streak of roughly 4 months with no seizures!

March 2019 update – still no seizures, getting close to a year now I believe. We bumped him down from 2500mg to 2000mg a day and his energy has gotten a lot better since then as well.

kartoffel happy dog

Today Kartoffel seems to not have any real lingering issues from the whole ordeal he went through, but I really wish we could have got him off of phenobarbital sooner since it was harmful to him.

If your dog is starting phenobarbital I would not be overly concerned – millions of pets and humans take the drug every year for seizure treatment and have no serious side effects. However if your dog starts having seemingly random auto-immune issues that appear as allergic reactions, talk to your vet about keeping a close watch on their blood cell counts and consider if it might make sense to switch medications if symptoms continue.

45 thoughts on “Rare Phenobarbital Side Effects in Dogs – One Dog’s Story”

  1. Carley

    I’m so happy to find this article! Our dog is going through a very similar experience. We believe the phenobarbital was causing her anemia and bone marrow suppression. But unfortunately she isn’t recovering, she has been off the phenobarbital for 10 weeks and her numbers haven’t improved but actually gone down. Our vet has hesitated putting her on prednisone but I think I will push for it now after reading your story. Thank you

    1. The Woof Whiskers Staff

      Best of luck, the Prednisone is no walk in the park for a dog either. Kartoffel got “pred-head” which is where the jaw muscles that run to the top of his head atrophy and you’re left with a very goof, pointy-headed dog! Eventually his pred-head got better once he got off the medication but he had some hind leg weakness as well. It was a tough time but at least his blood levels got back to normal eventually.

    2. Christina Ford

      Help! My 18 month old German Shepherd Husky mix began having “grand maul” seizures about 6 weeks ago. Vet did blood tests and all came back normal but he continued to have them 1-4 times a week typically all on the same day with nothing in between. So we found a new vet who would actually listen and look at my pup and he was prescribed phenobarbital. He has been taking the prescribed dose 2 times a day every day. The last couple of days I’ve noticed he seems to be favoring his hind quarters, today has been the worst of it to the point that I am helping him to stand up from a lie down position. My vet and the pharmacy we filled the medication with is telling me this is an expected side affect but after reading this I’m second guessing. He has no other symptoms at all just he seems weak in the knees for lack of other expression. Has anyone been told when going on Phenobarbital that this is a known side effect? Has anyone else experienced no other side effects but this?? This is my service dog, he has literally saved my life more times than I can count and I feel completely helpless watching him go through this.

      1. The Woof Whiskers Staff

        Did you get another blood test done to check his blood cell counts? From what I understand, inability to stand up is NOT a normal side effect from Phenobarbital. Laziness is, but not weakness of the legs. It could be a sign of a dose that’s too high or another issue.

        1. Barbara

          Phenobarbital – My small dog is taking 1/4mg, 2x a day. If 1/4mg, 2x a day is too much what can I do?

      2. Ataxia or weakness of the legs is normal when you begin Phenobarbital, or increase dosages. Pheno takes about 2 weeks to level in their system, sometimes a bit longer, depending on the dog. If its longer than that and he still cant walk definitely talk to your vet. I drive 2 hours to my vet with UC Davis in California, but i have a Neurologist that specializes in Epilepsy. I gave up on the local vets early on, they meant well, but just didnt have the background or experience that my dog needed. We have been doing this for two years now.
        Stay strong this is a very emotional illness

      3. Christopher Leventhal

        My dog was on 180mg of Pheno every day and was still having them. Then he had the grand seizure. After he came back from the dead the vet put him on Kepera. He has been seizure free for almost six months. I have almost started to relax and not having a heart attack every time he shakes his head.

      4. my 11 yr old Golden began to have seizures and was started on this. I too am having to even assist her to get up then she just falls over. I read a lot about the side effects and people have said its like their dogs are trying to stand on ice. This is exactly whats happening to Emma. Her rear end was a little wonky to start with but thank God for the full body harness we had from another dogs surgery. Since this drug doesnt stop seizures entirely we dont go anywhere..someone always has to be here as we have a 5 yr old female Golden who has and will attack Emma during a seizure. All the articles stated this will pass in about 3 weeks. I hope my back holds out.

  2. Whitney

    I just wanted to thank you because finding your story might have saved my dog, Maevis. She was started on phenobarbital in February and before starting all her blood work was normal two weeks ago she lost her appetite and started acting lethargic my vet’s really good and listens when I think something’s wrong and ran a full blood panel. She was severely anemic and her white blood cell count was very low they did x-rays and an ultrasound checking for internal bleeding and they couldn’t figure out anything they hospitalized her over the weekend and kept her on an IV and start her on immune suppressant for an autoimmune disease she had a very small initial Improvement so she got to go home but that initial improvement declined again a couple of days later. the vets had no idea what was causing it or how to help her. they sent her blood smear to a pathologist in town which we haven’t received the results yet, the next step is a bone marrow biopsy. the vets didn’t think it had anything to do with phenobarbital because her liver values were still good but I was searching online and I came across what you had written and I called my vet and asked her if it was a possibility she said she’d heard of it causing anemia in extremely rare cases but not a decrease in white blood cell count I told her about what I had read and she said she would do some research of her own the next morning she called me back and said that none of the vets in her practice had seen a dog have a reaction like that but that she did find some extremely rare cases like yours and we took her off phenobarbital this last Friday.  she had blood work checked this morning and her white blood cell count has improved quite a bit her red blood cell count went a little lower but her vet thinks that with this response it very possible was the phenobarbital. She said it could take up to three months before she gets back to normal values if it was the phenobarbital but I finally feel like there’s a little bit of Hope. Her appetite is starting to get a little better, shes still lethargic but seems a little more herself this morning. Through all the research I did this was the only thing that I found that led me to believe it really could be the phenobarbital and without it the vets would still be looking for some kind of an an answer and I’m not sure how longer she could have kept going or how I could have come up with any more funds so i cannot put into words how thankful I am that you chose to share your story. My dogs are like my babies and it would kill me to lose her thank you so much.

    1. The Woof Whiskers Staff

      Thanks for sharing Whitney, this is exactly why I wrote the article. My regular vet could not find anything wrong and did not think that the Phenobarbital could be the issue as none of the vets at the practice had heard of this scenario. I’m fortunate enough to have a large Emergency Vet nearby which has specialty departments with more expertise/experience which led us to the root cause.

      she had blood work checked this morning and her white blood cell count has improved quite a bit her red blood cell count went a little lower but her vet thinks that with this response it very possible was the phenobarbital

      I recall something similar (if not this exact scenario) with one of Kartoffel’s blood tests shortly after getting off Phenobarbital so I think you’re on the right path. Best of luck!

      1. My 2 year old Malamute has recently started having seizures and has started phenobarbital. His seizures are much like what you described, the jumping up afterwards looking scared with no recognition of us at all. He growls at us and foams at the mouth and as he starts coming out of it he approaches us and pushes us with his body. We are watching him closely on his new meds. I feel so bad for him.

        1. The Woof Whiskers Staff

          Yep, it’s certainly scary! Lots of slobbery foam to clean up after too. For what it’s worth Kartoffel is down to about 1 seizure a year now so it should get better.

  3. I was curious the age of your dog and the others who have replied? As well as what breed of dog. We have a Blue Heeler and she’s just been prescribed Phenobarbital for seizures. Because she’s 14 years old and has some kidney functioning issues I’m extremely nervous about about her taking it. Herding breeds can be prone to have adverse reactions to certain drugs because of a gene mutation. That’s why I’m asking about what breed of dog.

  4. “In dogs, seizures often occur in three distinct phases: … A seizure can last from just a few seconds to several minutes. The final phase is called the postictal phase, which occurs after the seizure. During this phase, your dog may seem restless, incoordinated and/or disoriented.“

    (Humans that have seizures also have this postictal phase.) Our lab after seizures is very confused, paces, runs into things, & has a hard time initially standing & walking on smooth surfaces. After a seizure, we have to give him medication because he is so anxious.
    Our lab started having seizures when he turned 4yrs (apparently epilepsy is common in this breed & usually rears it’s ugly head around this age is what we were told). Over the years, we have had to adjust his dosed Phenobarbital & start KBro to get better control of his seizures. We went through a period of time where I thought he was going to die because he was super lethargic & hard to wake, his KBro dose was too high. He does have weaker back legs than before, but some of that maybe due to his senior age now.

  5. My dog has just been weaned off phanobarbitral. Wow what a terrible drug she was on it for 19 days to start when she went in she gained 19 lbs. Was not eating het dog food the vet said give her boiled chicken . Watched the dog said she dod not have time to see her so i called around abd i wrnt to
    every night she was having a seizure. Called the vet that put her on the meds said that I needed to see her the receptionist said no she could not take her .found another vet now it was 30 days she was on the phenabarbatol she now had gained 30 pounds . She put her on keptra. Wow what a differance. Now going to get her off the keptra and put her on the cbd oils. They work with no side affects and are all natural. You just have to find a vet that will work with you on the cbd oils will let everyone know how it wirks.

  6. Lynda Wagoner Bogel

    Your article/narrative corroborates the experience my dog is going through right now. A three-year-old golden doodle, who started having seizures eight months ago (Nov. 2018), he was first put by local vet on zonisamide (100mg 2/day); when seizures continued, every ten to fourteen days (grand mal lasting 45 seconds, with post-ictal disorientation), he was examined by neurologist at Cornell Vet Hospital and prescribed phenobarbital (in addition to the zonisamide). First 60 mg/ twice a day, then upped to 90 mg twice a day. He developed two serious infections, which we could attribute to a) a bite at the dog park and b) a puncture to his foot in the woods; but the infections were more insidious than one might expect from those events. And most notably, he became seriously lethargic, didn’t eat much, walked like a drunken soldier–even while on the antibiotics. A week ago, as he continued to fail, our vet did CBC and determined very low white blood cell count. She’d seen this rare reaction to phenobarbital only once, but was sharp in having me cut back on the pheno- (90 to 60mg twice a day). YOU HAVE TO SLOWLY TAPER OFF PHENOBARBITAL.

    This morning, a second CBC showed yet lower white blood cell count, although Fennel is clinically showing enormous improvement: i.e., he is his old self with bounce in his step and appetite in his belly. In consultation again with Cornell neurologist, our vet is now cutting his pheno to 30 mg twice a day, for perhaps a week, perhaps a bit longer, with goal of easing him off completely. In the mean time, last Monday he was started on Potassium Bromide (a loading dose of 500 mg twice a day, for five days, now 500 mg once a day); and an antibiotic to compensate for his compromised immune system. I’m to keep some keppra on hand to feed him IF he has a seizure during this transitional period.

    It’s heartening to read of this other dog’s experience as one with a RARE distressing reaction to phenobarbital. Not for “misery loves knowing about company,” but for reading of ways through and out of this dismal forest. For those few dogs, the build-up of pheno takes a while in their systems to manifest its adverse effects, and a while when the pheno is being tapered and cut off for the white blood cells to get back up to speed.The symptoms of this allergy have been, to me, scarier than a seizure (though he hasn’t had, through all this trauma, a seizure in over five weeks).

    So, thank you for sharing your experience. And best of luck to all the pooches.

    1. The Woof Whiskers Staff

      Thanks for sharing your experience, Kartoffel is doing great on the Potassium Bromide, down to about 1 seizure per year. I hope your dog is having similar success!

  7. Adriana

    Omg my dog has the blood cell issue on that medication she is having a blood transfusion not not yet what will happen you article give me hope that she will be fine

    1. The Woof Whiskers Staff

      I would see if they can switch your dog to Potassium Bromide as I did, I have had no issues with that and blood levels have been fine since the Phenobarbital left the system. Good luck.

  8. My bullmastiff is 3 years old and just started having seizures, he has had 4 in the last 48 hrs and is now in the hospital under seizure watch, they have diagnosed him with idiopathic epilepsy and started him in phenobarbital. I’m worried about the side affects and don’t want him to become unhealthy, we are thinking about CBD oil but don’t want to stop phenobarbital incase it makes his seizures worse. I just don’t want him to become too weak to even walk or become not like himself, we love him too much! If anyone has any info please tell me

    1. The Woof Whiskers Staff

      I would definitely NOT recommend stopping the Phenobarbital under any circumstances without consulting your vet. When dogs are taken off it needs to be a really gradual process or you’ll see seizures again. I’ve heard anecdotes of CBD oil being good to give dogs in the midst of a seizure which potential shortens it or makes it less violent, but I don’t think there’s any evidence out there that CBD is a replacement for something like Phenobarb.

      Odds are your dog will tolerate Phenobarbital just fine and won’t have muscle weakness issues like mine did. I believe the most common side effects are increased drinking and hunger. Blood issues are pretty rare, so just go along with the Vet’s orders but get your dog’s blood levels tested if you see any more serious symptoms.

    2. Farrah

      My dog started with seizure around 6 months ago he was diagnosed with idiopathic epilepsy and is a cluster fitter he usually had between 20-27 in 24hours this lasted over two days,he was put on phenobarbital with not much at all changing with his seizures the vets we had were shockingly unhelpful we changed vets and they added keppra we use the cheaper substitute as keppra is so expensive his seizures have dramatically cut down with the most been 7 in 24 hours were starting kbr loading dose tomorrow I’m hoping this helps further as my nutty dog doesn’t seem to be his nutty self anymore I’m hoping to cut his phenobarbital right down as at the min he is on 90mg twice a day

      1. Hi, I don’t know if you’re still active on this blog, but wanted to ask if your pup ever suffered lasting effects after having that many episodes during a cluster fit?

        My German Shepherd had his first cluster a week ago, within 24 hours he had 7 “mild” episodes. Our Vet started him on phenobarbital in the midst of the fit & he hasn’t been the same since. Unfortunately she has been rather dismissive with us & our questions.

        He has displayed some symptoms/side effects that typically occur when first starting the phenob (sleepiness, ataxia, & frequent urination) but he is also seemingly blind, very disoriented & his “internal clock” is way off-he will start pacing/being active/wanting to go outside around 1:30am, only wants to eat at 3am & finally settles around 7-8 am…

        I will be making him an appointment with a new vet after reading everything here but I guess what I’m trying to ask is, did your dog suffer permanent brain damage from having such a large cluster? I can’t help but wonder if that is what has happened to Rex especially since it’s been 6 days since the last seizure & starting the meds….

        1. Hi Patti, I just found this thread. Phenobarbital takes approximately 2 weeks or a bit more to balance in a dogs system. My boy has cluster seizures as well. Our first event was 11 grand mals in 24 hours. It was the most horrible experience, we went to the local vet, they put him on Kepra but couldnt keep him overnight, so i drove him to the next town with a 24 hour vet, hes still seizing at this point, they kept him on Kepra and Diazapam IV over night and claimed the seizures were under control. His bloodwork all came back normal, so the only logical next step was CT scan, MRI and spinal tap. Luckily for us we had to move to UC Davis Veterinary School/Hospital. We got a Neurologist that specialized in Seizures (he siezed on the way there as well). The lesson in this is do not feel bad changing vets if you feel you are not getting the BEST where you are. We drive 2 hours one way for our vet now, but it is worth it!
          No brain damage so to speak. The first two weeks were terrible, we felt like we had a totally different dog! Slowly as the meds balanced and his system adjusted, our Brodie started coming back out 🙂 He will always be a bit different than he was, its inevitable with the meds, but it does get better and you find a new good.
          Hes a bit uncoordinated, a little dopey sometimes, doesnt always make the most rational choices, but he is our pup.
          He does get antsy for the first hour after his meds, i just let him do his thing and take him outside to walk if he needs it. During the night, i get up every 1 1/2 – 2 hours so he can go out and potty… thats my new norm.
          It is exhausting and trying, but it is the commitment i chose to make to save his life.
          ALWAYS watch for anything abnormal and talk to you vet no matter how simple it seems! Different dogs have different tolerances to any meds.
          Keep a daily journal of meal times/qty, meds/times, mood/behaviour changes.. it helps when trying to discuss issued with your vet.
          Good luck

    3. Farrah

      Ava try reading up on keppra or its substitute which is a lot cheaper I’m working with the vets to get my dog on kbr and reduce the phenobarbital as it causes lots of side effects and withy dog doesn’t seem to help much with the seizure,my new vet put my dog on keppra and the pulse therepy at home when he seizures works wonders,my 1year 6month french bulldog had his first seizures 6 months ago he is a cluster fitter and would have 30-40 fits over 48hours ever 3 weeks or so we have now managed to get him to at his worst 10 over 48hours and his best 4 over 48hours please read into keppra I lost all hope u till my new vet he is starting a loading dose of kbr tomorrow to try reduce them even more and with the aim to reduce him off phenobarbital all together

  9. Taylor

    My 7 year old Boston Terrier has had issues with seizures for the past 10 months, and we have tried a few different meds prescribed by our vet to target a few possible causes, but did not seem to completely resolve his issues. The seizures become worse and more frequent this weekend. He has now been on phenobarb for 2 days and I’ve noticed many of the typical side effects…the weakness and seeming drunk especially. But I’m noticing that he also is having some memory issues, like he doesn’t remember me, and is nervous of everything which is not like him at all. He didn’t even seem to know what a treat was yesterday which seemed crazy to me. Have you heard of anyone else experiencing this symptom?? I’m glad he’s no longer having seizures but I’m hoping his dosage won’t continue to cause this effect. It breaks my heart to think that he doesn’t seem to know who I am, and that he possible won’t remember how much I love him.

  10. Margaret Weinbroer

    Are sight issues, blurred vision or blindness side effects associated with Phenobarbitol? It has been at least 2 days since our beagle has had a witnessws seizure and he continues to be restless and bumping into furniture and bushes.

  11. Linda Vander Heyden

    I also want to thank you for posting your experience with phenobarbital. I rescued our dog (a shepherd mix) from a shelter last June. I gave her an oral tick med, and two days later, she had a grand mal seizure. I took her to an ER vet at a local trauma hospital because (of course) it happened on a Sunday. He put her on phenobarbital and said there would be an adjustment period where she would seem wobbly. Within about 10 days, she could not turn around without swaying, couldn’t stand, lost her appetite, and one day fell off the seat in the car. When I called the clinic that prescribed the med, they said she just needed another 10 days or so to adjust. I figured she could be dead by then. I started researching and came across your post. The next day, I took our dog to my regular vet and asked for blood work. Her white cells, red cells, and platelets were all “in the tank.” It was affecting her liver as well. My vet said if her platelets went lower, she might bleed internally. She was taken off the phenobarbital and has been on prednisone since. This happened in July of 2019. Her blood work improved within a couple months, and we’ve been weaning her off the steroid slowly ever since. She is getting very little of that now, but I’m sad to say the steroid has taken a toll on her body. I am grateful she hasn’t had another seizure since the one, and the longer she goes without one, the more I suspect the oral tick med was the cause. If only it hadn’t been a Sunday when it happened. I’d have gone to my regular vet. She said she never puts a dog on a seizure med after only one seizure. It would have saved my dog from so much suffering. Thank you so much for posting about your experience. I believe it saved my dog.

  12. Lynda Jonex

    Thank you so much for allowing us to read about the issues you have had with phenobarbital and your baby, Whiskers. I have a 10yr. old pit , she is on phenobarbital, for aalmost a year. The side effects you described are exactly the same as my Pug. The bumps under the skin, the increased eating and drinking, weakness in legs and more. She now seems almost deaf, and is confused a lot, especially at night. She too has seizures. Got to get her to the Vet for the white blood count you talk about. Thank you again, this article is so much help.

  13. Hi.

    The same thing is happening to my dog with no WBCS or RBCS or platelet counts. They keep declining she was on pheno for about 3 months bc of her seizures and vets think it could be that that’s causing all of this. She will not eat barley anything and now her blood levels have been decreasing. I see some hope they will hopefully return but was just wondering how long it took to see some results and how long your dogs were actually on the pheno for.? We have her on Kepra now for about a week and nothing has really changed for her. Besides blood levels declining. she is on a bunch of antibiotics to help fight infections bc of her WBCs. She is on anti nausea and appetite stimulate too. My poor girl my heart breaks.

  14. Jennifer Tyacke

    Jasmine is our much loved (12 yr old) Pomeranian. We have 9, but she is the Matriarch and rules the house.
    In regards to the ‘amnesia’ period coming out of a seizure, we had the same issue.
    ..she didn’t seem to know us and appeared scared. One seizure happened in the bedroom and without giving it any thought I grabbed my pillow ( I use a pretty flat one) and kinda put it under her head. When the seizure stopped she laid there for a bit, smelled my pillow and bounced up like nothing had just happened. At the time we marveled over her not seeming to be scared or not knowing us but didn’t put it together. Another seizure a couple of weeks later and we were in the livingroom as well as back to the ‘amnesia’. It came to me and I ran and got my pillow. It did not work giving it to her after the fact. The next time wasn’t for a few months. I remembered and again ran for my pillow and helped her little head on it. She ‘woke up’ like nothing had happened.
    This has worked every time since. Fyi … we are approaching three years without one! Thank goodness! I hope the pillow trick works for anyone that is also having the issues when waking up.



    1. I was just wondering how your St Bernard was doing now? I ask because my dog (2 year old poodle) had the same exact issues this week. She has been on Pheno for almost 2 months. I asked the vet if the Pheno could be causing the issues but she did not think so. The clinic had never seen a case like it. I mentioned this article and others like it, so she reached out to a Neurologist who confirmed it was a possibility. Our girl is weening off of the Pheno now and starting Keppra. I see some improvements, but she is still very weak. I am hoping your dog is doing well. Thanks for any info you can send my way. It seems like this will be a long journey to recovery.

  16. Kate Hussmann

    Hello. I’m wondering how quickly you were able to get your dog off the phenobarbital once you started the potassium bromide. My dog’s WBC count has become very very low on the pheno and I would like to get her transitioned to potassium bromide and off pheno as soon as possible. Thank you for posting this article. Very informative and helpful.

  17. Jessica

    I have a yorkie with similar issues indicated in this thread. We are weening off Phenobarb but he has no muscle tone in his hind legs, collapsing, limping, etc. Was started on PB back in February. Suddenly three weeks ago spiked a fever, got labs wbc extremely low. Ongoing saga, multiple vet visits, now they are telling me he has high wbc?? Anyone ever experience a sudden swing in WBC over 3 days?? Seems so odd to me. He is on antibiotics. Super lethargic and out of it. He was otherwise a normal dog 3 weeks ago. Any advice graciously appreciated.

  18. My 12 year old male boxer had his 1st seizure ever the day he took his second dose of a heartworm/flea/tick combo. Scariest day of my life. He had 2 seizures and 22 days later 3 more about 20 hours apart. He started phenobarbital 2 x day this past Friday and he is a little wobbly but (knock wood) seizure free. I appreciate all of the information and side effects and warning signs to keep a look out for. I really thought I was going to lose my baby boy when he had the first seizure.

  19. Hi. After reading a lot of these stories, I thought I should relay some of my experiences with my German Shorthaired Pointer Toby which started over a decade ago so details on timing are approximate. After the first initial scary seizure and a number of subsequent ones when Toby was 3 or 4 maybe, and vet visits, blood work, etc. we put Toby on phenobarbital which mostly worked well for a number of years though his personality & behavior changed somewhat. Most frequent issues – whether related or not – were frequent ear infections and development of some wart type bumps and fatty tumors one of which was on his side and grew quite large. At some point, Toby started having break through seizures which clustered one awful weekend to about every 15-30 minutes. Finally got him to his regular vet on a Monday morning and they gave him some additional medications, fed him intravenously, and took him home overnight and got the seizures to stop. It was a very rough period for him but we ended up doubling his pheno dose and adding potassium bromide which kept him seizure free though he suffered some more – mostly temporary – personality & behavior changes. Long story short, after some years of no seizures, I inadvertently at first because of a lapse between prescriptions being filled began lowering his phenobarbital dose and when there were still no seizures and he had more energy and was happier, etc. I quit giving him phenobarb and advised his vet. Quit the potassium bromide which was expensive and was shipped from out of town either before or after – not at the same time – to gauge any effects from either drug separately. Blood panels every year or two showed no effect on liver while he was on the pheno. but I do wonder – and have found perhaps one study suggesting a correlation but scant research on – whether the medication contributed to his very large fatty tumor which we just had removed during a sedation for dental. It’s been a number of years since he’s been off the pills and no seizures and the chronic ear infections are also gone. He’s also less stressed by fireworks and other loud noises (if hearing loss, it’s minor because he responds to voice; like kids, he’s always had “selective hearing” and is much more independent, stubborn, and more frequently as he ages vocally demanding especially compared to his brother/litter mate Romsley. I do wish I’d tried to wean him off the pheno sooner and worry that it might have contributed to his current issues. I’d thought for a while he had tachycardia (rapid heart rate) which the vet initially discounted but did find a heart murmur for the first time recently. An x-ray indicated an enlarged heart and in hindsight I do think that perhaps his chest has increased in size though he’s never had any kind of weight issues despite no longer matching his smaller brother’s speed and endurance (fastest, most agile dogs at the dog park for years) after the seizures/phenobarbital. So Toby is now on Vetmedin (tough to find locally right now) and benazapril for CHF and appears to pant a little more frequently and will sometimes collapse onto his stomach and need help getting up – usually after reaching up onto a counter to steal something he shouldn’t or knock something over because he’s mad I’m not feeding him seconds or thirds (appetite is great so that’s good I guess) but otherwise doing pretty well physically. Since the dental (only 2 extractions) and lump surgeries, he’s quit climbing onto the couch and beds where he used to snuggle; he now lies almost exclusively on a dog bed or the floor often in front of the AC. Now if we could figure out why his brother still had mouth pain and how to get them to allow nail trimmings. A pair of groomers had been able to corral Toby to do his while I was able to do Roms a few at a time but after the closures . . . we’ll be back to square one. My advice? Use the pheno or just potassium bromide if it works to avoid seizures but wean them in consultation with vet if seizure free for a few? years. Good luck!

  20. My dog was put on phenobarbital 4 days ago. Since that time, she has had mild side effects (increased appetite, lethargy) but the most concerning one is she has not been able to stand up on her own. She’s almost 12 (Golden Retriever) but always was as active as a puppy. How long before your dog was having hind leg issues. Was it days? Weeks? I am just trying to figure out if I should ride out the 7-10 days of side effects my vet told us or to ask to titrate my dog off of pheno and start a new med.

    1. Allison

      My 13 year old lab mix Cassie had her first ever seizure about a month and a half ago- scared the crap out of all of us! Loaded her into the car and off to the emergency vet- these things only happen on nights or weekends, right?! They did bloodwork which all looked good. They said if she continued to have them, to follow up with our vet. About a week later she had another and our vet called in a prescription for phenobarbital. I didn’t fill it right away because I didn’t like the potential side effects. I started giving her CBD oil because I’d heard many stories about it helping. She was seizure free for about 3 weeks, but then had another. I filled her Rx and she’s been taking pb for 5 days now…. She’s definitely sedated to some extent and has some loss of coordination- along with a few other known side effects of starting this drug. But after 5 days, loss of coordination doesn’t come close to describing her ability to get around. It’s like she is completely drunk. 9 out of 10 times, we’re having to help her get up (like her back legs don’t want to work) and we try to follow her around once she is up to keep her from bumping into things and to keep her from falling over. While walking, her front legs often cross in front of each other, her paws seem to get ‘stuck’ under her and because of the way she’s moving/falling, I’m afraid she’s going to break a bone. This can’t be right. I’m starting to think having a seizure once in a while is much better than the bs she’s having to deal with right now.

      Thank you for sharing all your stories about phenobarbital… I will definitely be calling the vet on Monday!

      1. We are having the exact same issue with our 12 yr old lab mix. We are on day 11 of phenobarbital. Calling vet today because she is so out of it ! Do you have an update on yours ?

  21. gabriela garcia

    Thank you for writing this. We’ve had our girl kona on pheno since she was 1 back in 2018. Her first seizure scared us and we didn’t know how to react but panic and rush her to the vet. While doing so, our neighbors dogs were barking and we were frantically trying to get her into the car safely and quickly but when she came to, she had this scared, crazed look in her eyes and growled at us which she’s never done before. She’s had many seizures since then but has never again been aggressive. We find it helpful to be as quiet as possible and make it dark in the house during her seizures. It also helps to stay calm and gently pet her. Since we’ve started doing that, she comes to faster and is super happy to see/hear us. It’s been a very long journey of ups and downs. Now here we are, 3 years later and she’s been struggling with hind end weakness thats getting worse. We took her off pheno and bromide (along with a completely whole food diet) recommended by our vet and patiently waiting to see what’s next. The things we do for our fur babies! Best of luck to everyone!

  22. Robert Marcum

    My sweet Aussie has been having seizures for 7 of her 8 years. She has been on phenobarbatol, tried potassium bromide (she seized 1 hour after she received the dose for a week before i stopped. she is now on pheno, valium and prozac, then tramadil for pain from double hip displaysia for 3 years. Lately she has been seizing almost every day, some small and some like this morning, 20 minutes before I was able to get her on her feet. her demeanor has changed this week, instead of the head following me around with bright eyes, she don’t move her head up, just lifts her eyes. She looks so sad, I am wrestling with the final option.

  23. Chastity Jackson

    I just gave my Pitbull one dose after vet prescribed phenobarbital for her seizures. She is having more seizures and 6 hrs after first dose is having problems even standing. I am not giving her anymore. I hope something else will work for her cause and I haven’t messed her up more with this medicine. I am shocked that one pill could make such drastic changes so quickly. I hope she will be okay.🥲

  24. Deb Hooks

    My little pup had her first seizure in October of 2017. They were infrequent and lasted a couple minutes and she always came out of them and was back to her normal self within a few minutes. I still hated to see her have them at all so I started her on the CBD oil and it seemed to work for quite a while. Then this fall they became more frequent like maybe 4 times a month and in Feb. she even had 3 in one day within about an hour and half time frame. So I finally agreed to start her on levetriacitam. 2 doses a day. Actually the 3 in one day happened after she was on the leve for a couple weeks so vet said increase to 3 doses a day. She continued to have them so the decision was made to transition to the phenobarbital. After 16 days on the pheno she woke last Friday barely able to get up. She had had a seizure the day before which the Dr. said was probably causing the problem but I explained to her that she was fine after the seizure on Thursday. Vet only checked her pheno level on Friday while we there and said it was ok but also said she had a fever so she gave me an antibiotic to start. Saturday she was worse and now vomiting. I insisted on bringing her back in but they were only gonna give her a shot for the nausea. When I got there vet agreed to do a full blood panel which determined her kidneys and liver were out of whack, she had anemia and an infection somewhere in her body. They kept Sat. night, Sunday and Monday when they were closed. I couldn’t see her till Tuesday at 3 and when they brought her into me I was not prepared to see what I saw. She literally was moaning in pain and struggling to breath. Nothing in any of the Dr.s text updates indicated how bad she was. She wanted to keep working on her but all I was seeing was my beloved pet in agony. She finally agreed to another blood panel since she hadn’t since Saturday when I brought her in the second time. Kidneys were 3 times as bad and liver was not improved either. She was now in total renal failure. My precious baby suffered for 4 days and 3 of them without me. I had to make the heartbreaking decision to let her go. There was no coming back from the damage done. I lost my baby on Tuesday, April 12 when I went in thinking I was just gonna try to get her to eat. Vet said it wasn’t necessarily the pheno but you’ll never convince me of that. She was fine till she had 16 days worth of that crap. Honestly she was always right back to normal right after the seizures. I feel horrible guilt for putting her on that pheno.

  25. Sandra Hoerle

    my chihuahua is now 13 years old , he has been on phenobarbital twice a day for years only has a sizure a few times a year but his lasts for hours not min , he gets stiff and pants like crazy mouth wide open , after mabe a night he seems to be fine but acts a bit draggy for a day or so , seems to me like stress brings these on , if a loud thunderstorm or something simular upsets him , vet told me i can up his dosage if needed but i sure dont want to poison him , cant tell if it helps or not but twice now he had one just after his evening pill, so maybe i need to cut it down? hes on a half in morning and whole pill at night its a low dosage , i was just conserned about how long they last as most perople say there dogs last only a few min

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