Phenobarbital levels

[Amanda and Quinn]

The good news: Quinn has not had a seizure since early January 2012, so we’ve made it a year seizure-free. I’m sure he hasn’t had his last seizure, but for now we seem to be doing well with a combination of Phenobarbital and doing our best to avoid his known seizure triggers.

The bad news: I just got his latest blood work results, and his Phenobarbital level is at 38. The cutoff point for acceptable levels (where the risk of toxicity begins) is 45. His levels have previously been in the twenties, so this is a sharp uptick. I just spoke to my general vet, who will forward the numbers to his neurologist. I would normally just hash this out with his neurologist, who I trust completely, but she’s out on maternity leave. There are other neurologists at the hospital, and I’ll be speaking with one of them in her absence, but I haven’t had the same confidence in their knowledge when I’ve dealt with them before.

My general vet felt that because he’s been doing so well (no seizures, no outward signs of Phenobarbital issues like lethargy and unsteadiness), we should stick it out at the current dosage and re-test in 3-6 months. I re-test every six months anyway, so I would do it at the 3 month mark. I guess I’m just looking for advice from other Pheno users… would a level this high make you nervous enough to want to lower the dosage now, without waiting it out? Quinn will be 5 in May, and I expect he will need to be on this medication for the rest of his life. We did not have any luck with any other anti-seizure medication. I’m afraid that if it’s this high now, we’re looking at serious problems down the road.

[LG & Sadie]

Hi Amanda, yes & no is my response. I would get nervous because that's what I do as Sadie's Mom-but I would remind myself I think and have been told blood levels can be fickle. The time of Quinn's last dose, how much food he had in his belly, all of that could affect the reading the day you tested and 38 is not 46, you have got some wiggle room. My opinion for what it's worth (I am not a Vet in or in any way dog medical) I would re-test in 3 months and maybe by then the Neuro you are most comfortable with will be back from Maternity leave to advise you if it's still running high. Quinn's a lucky boy! Sadie will be 6 in Feb so I think a pheno combo is probably what she'll be on for life too. Hang in there and please keep us posted. Take Care & Good Luck! LG & Sadie

[Karen, Jasper and Jackdoodle]

I have no experience with this, but LG's advice makes complete sense to me.

Hope Quinn continues to do well.

[Kirsy & Jasper]

Hey Amanda,

Was this PB level test trough (taken just prior to his next Pb dosage) or peak (taken approx. 4 hours after his Pb dosage)?

If it was taken PEAK I would not worry so much about the 38 reading, but definetly keep up Milk Thistle supplements for the liver! If he had this high level at trough I might consider lowering a tiny bit, say 10%of his normal dosage, but not without checking with a vet first!

Jasper first PB was taken peak and he had 76 umol/L (normal range 65-170). Just recently we had a trough test done, just 20 minutes prior to his next dosage and he only got 61 (normal 65-194) = 15-45 ug/mL...he is under the therapeutic range!

So I am worried, that he could get a seizure...BUT he has been going so great since we started him on PB at Easter last year. Only one mild breakthrough in August. I will just leave things as they are.

[Mary]

I have a 5 y/o Mini Labradoodle who has had seizures since age 5 months. She is on Phenobarb and Zonisamide twice a day. Her levels are high, 45- she is only 17 pounds, but the vet wants hers on the high side due to the severity of her seizures. hers are uncontrollable, she has been on every seizure med there is and this combination seems to work the best. She still has seizures at least once or sometimes 2-3 times a week, but they are not as bad as they used to be.

[Amanda and Quinn]

Thanks so much for your input, everyone. I think I am going to leave things as they are right now and test again at the 3 month mark. As LG said, the neurologist will likely be back from maternity leave then and we can talk about where to go from there if the levels are still high. It's always helpful to get feedback from other people going through this.

Hope those of you affected by this cold snap are staying warm today!