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  Discussion on Equine Juvenile Epilepsy Hereditary?
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Posted on Saturday, May 15, 1999 - 3:45 am:

I am a brand new member. I joined after finding help and information in the Juvenile Epilepsy in Horses article by Dr. Oglesby. We have a one month old Arabian foal who had a series of seizures today. Our Equine Veterinarian was not available, and we found ourselves on our own with this for several hours until another Veterinarian could be summoned. The new Vet is not an equine practitioner, but he did as much as he could to help us. He gave our little fellow IV fluids and did a routine blood work up which was all within normal boundaries. The foal was as healthy as a, well, HORSE until this incident. I showed the Veterinarian the protocol prescribed in Dr. Oglesby's article, and this is what we plan to follow in the morning. I will also call in our regular Equine Vet who will hopefully be able to respond tomorrow. What I want to know is whether anyone has any information about whether this condition is genetic (hereditary), or is it just the luck of the draw? The sire of the foal has only a dozen offspring, none of which have had epilepsy. The mare has had two other foals, but they were not purebred Arabians (sired by other breed stallions). Going through this today with our colt has been heartbreaking to watch. If there is any evidence that this may be an inherited condition, we want to do whatever genetic testing might show us which parent may have carried the problem gene. Sorry to be so wordy, but I'm terribly worried about my foal, and concerned for the future as well. Thanks for any and all advice. Nina email: sagafarm@aol.com

Posted on Saturday, May 15, 1999 - 1:14 pm:

Hello Bryan,
I wish I had more to add, this is not a problem I have actually had to deal with. Since I have a fair number of Arabs in the practice it must not be that common. All the reports suggest a hereditable component but this is based on the fact that Arabs seem predisposed. I do have these references:


Recurrent convulsions in a thoroughbred foal: management and treatment.
Vet Rec 1977 Jul 23;101(4):76-7
May CJ, Greenwood RE

A thoroughbred foal had a convulsive attack 12 hours after birth followed by further convulsions on the 10th, 11th and 12th days after birth. It was treated successfully by medication with primidone, feeding by stomach tube and careful nursing.

Preliminary study on the pharmacokinetics of phenobarbital in the neonatal foal.
Equine Vet J 1984 Jul;16(4):368-71
Spehar AM, Hill MR, Mayhew IG, Hendeles L

Pharmacokinetic characteristics of the anticonvulsant phenobarbital were studied in seven pony and two Thoroughbred foals aged between four and 10 days. A single, 20 mg/kg bodyweight (bwt) dose of phenobarbital was given intravenously over 25 mins and the serum concentrations of the drug were measured using an EMIT AED assay (coefficient of variation 1.37 per cent at 30 micrograms/ml, n = 7). Phenobarbital elimination was found to follow first order kinetics. The mean (+/- sd) peak phenobarbital serum concentration was 18.6 +/- 2.1 micrograms/ml at 1 h after initiation of infusion with a mean (+/- se) half-life of 12.8 +/- 2.1 h. The mean (+/- se) volume of distribution was 0.86 +/- 0.026 litres/kg bwt and mean (+/- se) total body clearance was 0.0564 +/- 0.0065 litres/kg bwt/h. Sedation was noticed 15 to 20 mins after the beginning of infusion and lasted for up to 8 h. All foals could be aroused and could walk although they were ataxic for the first 1 to 2 h. A degree of delayed hyperexcitability occurred 3 to 8 h after infusion. In equine neonatal seizure disorders it is recommended to use a loading dose of 20 mg/kg bwt of phenobarbital, followed by maintenance doses of 9 mg/kg bwt at 8 h. With this regimen, average steady state serum phenobarbital concentrations should range between approximately 11.6 and 53 micrograms/ml. Phenobarbital serum concentrations should be monitored following the loading dose and 24 h after initiating the maintenance doses to check that levels remain within the suggested (human) therapeutic range of 15 to 40 micrograms/ml.

DrO

Posted on Saturday, Jun 5, 1999 - 4:26 pm:

This one did not have a happy ending. We lost our colt two days after he went into convulsive seizures. He had been transported to the University of Missouri Veterinary College where everything possible was done for him. Still, he had such frequent and severe seizures that I made the decision to let him go in peace. The results of a necropsy performed on the colt revealed no injuries or diseases which would have brought on such virulant seizures. It is believed that he suffered from juvenile onset epilepsy, but it was our bad luck that his condition was not manageable. The doctors at MU had not seen the condition often either, and never as severe as our colt's. Our vet did not feel it was inherited from the colt's dam or sire, but we were still worried. After carefully studying our foal's pedigree and checking the history of dam and sire, we believe it is not any more likely to happen from the mating of these two horses than from any other mating of two ARABIAN horses. If anyone else who raises Arabians has further to add to our experience, we would like to know more. Thanks! Nina and Bryan

Posted on Thursday, Nov 11, 1999 - 8:31 pm:

I just happened to see the note from Bryan and Nina about their experience with equine epilepsy in foals. I am so sorry for your loss. I have gone through somewhat of an ordeal myself. I joined the "Advisor" because my first foal had a seizure at 6 weeks of age. Yes, an Arab. To bring you up to date. She is now almost 6 months of age and in the process of being weaned from her mother. We were a little delayed in the weaning process, because at 4 months of age she suffered another epidsode of seizures. She banged herself up pretty bad. We thought she would loose vision in her right eye. But as of today, her appearance couldn't be more perfect. She has been on Phenobarbital since Aug 20, 1999. A dose in the am and pm with grain.And seizure free. I spoke with our vet last week and he seems confident that we should start to wean her from this medication. I on the other hand am not quite ready. I can't help but think of what could happen if I take her off this medicine. There has not been a lot of info on this topic. Just that for some reason it occurs in Arabs more frequently. And that Phenobarbital is the drug of choice. Hopefully she will grow out of this before she is a year, time will tell. I am not able to look to far into the future with her, we take it day by day. Every morning I go out into the barn and hear her call, I think to myself another day under her belt. Everyone is so free to give advice. That she sould have been put down after the second episode. But the vet wanted to try her on these meds and give her a chance. That brings you up to date. Keep you posted.

Posted on Friday, Nov 12, 1999 - 7:16 am:

Julie, Thanks for taking the time.
DrO

Posted on Friday, Nov 12, 1999 - 9:22 am:

Dear Julie, boy do I know how you feel! Mine is a late onset epileptic adult horse who has a twice daily fix of phenobarbitone to keep her safe and leads a completely normal life - I even compete her at a local level. My vet had intended to try weaning her off after 6 months of treatment, reducing by 5 tablets per week. I put it off and put it off as I had a nasty feeling that my horse would just start having seizures again - I still believe hers are a sort of allergic reaction to something she is in contact with or eating. Anyway she is still on the same daily dose as she did have a seizure a few weeks ago, probably due to a combination of 2 days of over-excitement and disturbed feeding times and my vet has agreed to abandon the weaning off idea. I was feeling much more relaxed until my vet then told me that phenobarbitone is being massively restricted by the government and the drug companies have put the price up x7!! Dr O, my consultant at equine hospital has suggested some alternatives which he thinks should work quite well, I'll keep you posted on what he suggests and how much.
Julie, there are foal helmets which might give you some peace of mind while you reduce your baby's medication. Perhaps you could hire one. Talk to your vet about it. Also, I don't know what bedding you use but keep the banks high to protect her joints if she does go over.
People who have never seen a horse having a seizure are lucky, its so distressing and all you can do is get out of the way. My mare blunders about while she is having one - I wish she would go down and stay there until its over but she never does anything by the book!
Please let us know how your foal goes on.
To Nina and Bryan, my heart goes out to you, I'm so sorry that you lost your colt.There is extra tragedy when it was only a baby.

Posted on Saturday, Nov 13, 1999 - 5:08 am:

Helen, you are giving me hope that she might just lead some what of a normal life. We have to go out of town for a few days and someone will be staying at the house. I did not want to mess with her doasage while someone else was here.Bedsides she has ony been separated from the mother for 3 weeks and in my mind she is still going through some stress. Bottom line ,I am not ready to decrease her dosage.
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