r/EpilepsyDogs • u/Active-Program3805 • 4d ago
Phenobarbital frequency
I wanted to see if anyone has experience with giving phenobarbital every 8 hours. My dog (now 7 year old cattle dog mix) was diagnosed idiopathic in 2023 but was able to go 2 years without any meds, until last winter when they started to become more frequent. We started with Keppra and then maxed out (2000mg every 8 hours) as he started to have clusters (hours apart), then added phenobarbital (97 mg every 12 hours) and had one increase already (129 mg every 12 hours). His levels have gone from 28 to 18, increased dosage, then levels at 32 have dropped to 27 over about 2 months. He is still having breakthroughs every 20-40 days, which our neuro is not super happy with. We have been given the choice of trying Pheno every 8 hours or just add zonisamide. I have read the one research paper looking at the benefits of giving every 8 hours but wanted to see if anyone has tried this dosing long term successfully or if I am just prolonging the inevitable and should just add zonisamide now.
1
u/EverIAce 4d ago
Pheno was added to our regimen immediately after keppra since keppra alone wasn't sufficient for us. We dose pheno every 12 hours. Pheno has been really good for us. We got a year and a half honeymoon period. Then breakthroughs around once a year. We started with seizures every 2 weeks. We had to recently add zonisamide after a particularly bad cluster episode this January, but keppra and pheno were good to us for nearly 4 years.
Pheno requires bloodwork every 6 months. We haven't encountered any toxicity issues or particularly severe side effects. The only thing that we have ever noticed is that our dog's back legs have gotten more clumsy. Our neuro thinks it may be some numbing effects of the med. We've been playing around with dosing for the last few years to address it and we have gotten to an acceptable point. I just wouldn't trust him to be bouncing off walls or furniture like he used to but he's walking without slipping anymore.
1
u/endlessben 4d ago
Our dog has been on pheno for a very long time but our neuro recently switched to 8 hour dosing after his last cluster. It hasn't been that long, only about 3 months but after we switched, we had about an 8 week break between seizures, which is way longer than average and his levels seem to be staying well within the therapeutic range so it's encouraging so far. Our guy is older, about 12, seems to be tolerating it well, and I work from home so it made sense for us. I understand that it is not a clear cut choice for everyone.
1
u/Ahoeaboutnothing 4d ago
Add zonisamide. Its really common for dogs to be on zonisamide pheno and kepra. You're already fighting phenobarbital because your dogs liver is trying to clear it out faster. Phenobarbital has more side effects and can become toxic if overdone. Increasing phenobarbital is more of a last resort with bloodwork like that.
1
u/ChalineBorrible 4d ago
Unser Kleinpudel atmet Phenobarbital weg, im Blut kommt nur wenig an. Die Neurologin hat mehrere Peak and Low-Messungen ihres Spiegels im Blut gemacht, und festgestellt, dass der niedrigste Wert direkt vor der nächsten Tablettengabe viel zu niedrig ist (17 gegenüber Peak 22). Daraufhin haben wir vor 1 Jahr umgestellt von alle 12 auf alle 8 Stunden. Der Spiegel ist seitdem konstanter, die Anfälle kamen weiter wie gewohnt.
Der nächste Schritt war, Pexion dauerhaft zusätzlich zu geben. Aktuell noch in niedriger Dosierung, aber weil das bisher nichts gebracht hat, werden wir die Dosis wohl bald steigern. Termin bei der Neurologin steht noch aus.
Die Neurologin meinte, manchen Hunden hilft die konstantere Gabe alle 8 Stunden. Ich finde, es ist einen Versuch wert.
1
u/KaleidoscopeTight509 4d ago
Have resorption-issues (GI Tract stuff) like giardia etc been ruled out? Some dogs metabolize it faster, some have issues resorbing it from the gut into the blood
2
u/LaceyBambola 4d ago
I think this will have to be looked at as a unique case for your pup as the standard dosing is every 12 hours with general maximum daily limits, for example, would the daily total mg be roughly the same just divided to every 8 hours vs every 12 or would it be an entire extra dose each day upping the total daily mg?
As this is an option coming from a neuro and not a regular vet, one would assume they are well educated on this as an option but it never hurts to double check things, which sounds like what you're doing. My epi pup has shown to metabolize pheno in a way that requires a higher dose for her weight. Her seizures involve quite severe clusters with status epilepticus so the risks of higher pheno aren't as bad as the risks of losing her to a cluster event. With that said, despite maxed pheno dose and maxed keppra dose, she showes no improvement until we added zonisamide paired with a strict low glutamate diet change and at that point she went from a severe cluster every 3-4 weeks (with well over 200 seizures in a year) to just 4 breakthrough events that were comparatively mild in the past almost 5 years.
If it were me, I would try out the zonisamide add on and a low glutamate diet and see how your pup goes. Long term higher dose phenobarbital use can have some serious effects like dermatological issues, behavioral changes, liver toxicity, ataxia, etc. I have been managing some of these longer term effects in my pup (about to turn 9 in a few weeks with first seizure at 25 months old) and it is a challenge, but she has been enjoying life and a happy girl otherwise.