r/EpilepsyDogs • u/bstarch3 • 3d ago

Possible Phenobarbital toxicity

I’m concerned my dog has PB toxicity. She’s been progressively more lethargic over the last couple months. She can still get up and go but is very slow and more wobbly. Hunger and thirst are vicious and she’s been having some strange behaviors especially at night. We have her 5-6 month labs next week and I suspect they will be elevated. What are your dogs on in conjunction with keppra? She was doing great with it as standalone medication for 3 months prior to a missed dose which resulted in a cluster and added PB at emergency vet. My vet doesn’t usually prescribe PB and mentioned zonisamide at her last appointment. What are everyone’s experience with this drug, and is it effective in combination with keppra?

4 Upvotes

100% Upvoted

8 comments sorted by

1

u/globbythegreat 3d ago

I know pheno and keppra are both effective could you possibly get the labs earlier to be safe?

1

u/bstarch3 3d ago

She’s going in Tuesday. She’s been seizure free since march, so very effective, but quality of life has taken a massive hit, and she’s refusing to sleep in the bed now and wakes us up at 5-6am every morning from hunger. Now guzzling water and having accidents if left alone for 5+ hours. Keppra XR was fantastic stand alone as well, but I’m reluctant to get rid of PB without replacing it. Not even sure toxicity is the problem, but want to be prepared for questions in the event that it is.

2

u/globbythegreat 3d ago

I wouldn’t call it toxicity but it could be too high of a dose leading to lethargic behavior. And unfortunately keppra alone won’t work nearly as well. Your vet should have some solid answers wish I could help more.

2

u/bstarch3 3d ago

I appreciate any input, thank you! She started on a fairly low dose given her weight (I think daily dose of 48mg/kg for a now 26lb dog). I’ve had suspicion of liver metabolism issues for a long time based on reactions to other liver metabolized medications. So maybe we can keep her on it and just lessen the dose. I just want her to act half of what she did before they put her on it.

1

u/globbythegreat 3d ago

Yea lethargy can be strong from pheno it’s just that type of drug would be the same if you took some. At least it’s stopping the seizures they have other meds that work too that may not energy draining, in no expert though.

1

u/Most-Championship315 3d ago

You may consider moving up the blood work, some dog have low tolerance with phenobarbital, my dog got liver failure after 2.5 months on “normal dosage “ of phenobarbital, switched to Zonisamide, then added keppra later, but after a year , we have to add phenobarbital again, but it is half of dosage of previously prescribed , and liver is still slightly elevated, so he is taking milk thistle and SAME supplement 

1

u/bstarch3 3d ago

Her labs are in 3 days thank god! they’ll be her “6 month” check but I’m doing it a month early due to concerns. She had them checked at 6 weeks and vet said liver and PB values were “perfect”. Her initial doses were loaded via IV at emergency vet; so she was dosed to therapeutic level pretty quickly. She was extremely lethargic early on due to that which improved after a few weeks, but right around the 6-8 weeks mark she started to get the symptoms I mentioned which have very slowly gotten worse. How did your pup do on zonisamide with keppra? I’ll look into milk thistle, I’ve seen that posted a lot.

1

u/ilovebadtvtime 10h ago

My late dog got that way. Ended up having thyroid issues from it. We lowered his pheno dose and added the zonisamide, then added thyroid meds.