Phenobarbital side effects

[cherbear1975]

My dog Bella started having seizures a few months ago (she is 5 years old).  Her first seizure started as a focal seizure and then into a grand mal seizure that was followed by two more seizures over the next 8 hours.  After that she was having cluster seizures weekly.  
The vet did bloodwork  and put her on zonisamide 100mg twice a day.  She continued having them so vet doubled her dosage to 200 mg twice daily.  She continued having them but they were much shorter in duration.  So the vet added phenobarbital 1g twice daily in addition to her zonisamide 200mg twice daily.  My question is about the side effects.  It has been a week since the pheno was added and she is still very clumsy and can't even walk up stairs.  She is eating more than usual and sleeping constantly.  Is this normal after a week?

[tonyb286]

Hi.

What food is it? Please give full details.

Yes, the side effects are very frustrating and many owners get extremely worried by them ... but sticking with the medication is the ONLY way you can help your dog right now. Blood testing is important, so if you are concerned about the side effects, get the vet to do a blood test to assess dosage levels. But, the side effects CAN continue for several weeks, before they will eventually start to subside. I know it's a hard process - but it has to be gone through - otherwise you will be back at square one.

Don't interfere with the dosing without the vet's authority - and importantly, give the dose at the same time every 12hrs. Even an hour difference can make a big impact, so try to maintain a good routine with the times.

Tony

[cherbear1975]

The vet did blood work and said it all came back fine.  Vet told us it was epilepsy. She is not exploring any further than the blood work.  The seizures started out of no where and started with clusters weekly.  No chemicals and she is on same food her entire life.  No environmental changes at all.  
  I am just concerned as she is getting even worse. No seizures, but side effects of medication is just unbearable.  She is on 200 mg zonisamide every 12 hours and 1 gr. of pheno.  Is this maybe too much.  She has been on them 9 days and side effects are worse every day.  
Today she was wedging herself in any corner she could and now I am having a hard time waking her.  She is urinating while sleeping and it takes about a half hour, or longer to get her to wake up.  I did call the vet today, but am waiting for a call back.  

[tonyb286]

Hi. Yes, the side effects are absolutely normal. They will last between 2 to 8 weeks, so you may need to be prepared for some odd behaviour for a while. The drunk-like state needs careful supervision, particularly on the stairs, as her coordination is severely impaired and will be so for a while. Once the "therapeutic level" of phenobarbital has been found (it's a bit trial and error), the side effects should start to dissipate.

Of course, the question is why did the seizures begin? Bella is quite young, but being almost in mid-life, it could be either genetic (though this ordinarily occurs in younger dogs) or physiological, where another primary illness has triggered the seizures. This is certainly something your vet should be exploring. Have they suggested any cause? What are they doing to try and identify the cause?

Another possibility is environmental - food and poisons are triggers for acute seizure attacks. What are you feeding Bella? Did you apply any chemicals in the home or garden just before the seizures began? Has Bella got into any human medicines or any other things she shouldn't?

It would be useful to identify the cause and whether it's acute or chronic - because if it's the former, you may not need to have her on anticonvulsants forever. If it's a chronic condition (epilepsy), then she'll need to stay on the meds for life, and she'll also need very regular blood tests to make sure the meds are within the appropriate dosing range.

Tony