Odd behaviour-any neurologists out there?

Re: Odd behaviour-any neurologists out there?

James Laidlaw — Wed, 22 May 2013 17:20:29 GMT

[quote user="Mark Lowrie"]

[quote user="James Laidlaw"]

Does pexion not work by binding the same receptors as phenobarb, thus function in the same way, but without the side effects of phonobarb, or is the "company line" not strictly true in that respect? I would have thought if the medication (although new) has the same function and effect, but without the need for monitoring or the toxic side effects that it would be worth a try, but have only heard from the manufacturers, and not specialist opinion at this stage?

[/quote]

Hi James,

Pexion (structurally similar but distinct to benzodiazepines) is different in function to phenobarbitone (a barbiturate). They do both work at GABA receptors but phenobarbitone binds to the beta subunit whereas Pexion binds to the benzodiazepine binding site of the GABA receptor therefore offering different modes of action. One study has shown that when Pexion is added to phenobarbitone, the combination of drugs offers better seizure control in some patients.

The only peer-reviewed study investigating the efficacy of Pexion compared to phenobarbitone involved 12 dogs receiving Pexion versus 44 dogs on phenobarbitone. I am sure as it becomes more widely prescribed we will become more familiar in understanding whether there truly is the potential for further adverse effects and indeed how effective it truly is.

However, I am not comfortable with using Pexion in a therapeutic trial for unusual paroxysmal disorders as I have no experience with it in this way and so would find it difficult to know if a lack of response is due to the fact that the paroxysmal episode is not a seizure or simply because we are failing to adequately control the seizures. This is why I prefer phenobarbitone for therapeutic trials of this nature.

I really think Pexion should be reserved as a first-line drug for the management of idiopathic epilepsy in dogs – the thing for which it is licensed for.

[/quote]

Thanks Mark,

Just wanted clarification - I'm not about to go using it for everything!

James

Re: Odd behaviour-any neurologists out there?

Christina Smith — Wed, 22 May 2013 17:10:58 GMT

http://www.veterinary-neurologist.co.uk/lafora.htm

Re: Odd behaviour-any neurologists out there?

tess — Wed, 22 May 2013 16:24:20 GMT

Thanks for your reply, Mark. . From what I understand she can be pottering around the garden, then will sit down and stare upwards. Sometimes she seems to be sniffing the air as she's doing it. I think the reason for not catching the start of it on film is that the owners are reaching for the camera at the time. An estimate given the film length would be 15-20secs per episode.

There's no salivation ,defecation or abnormal limb movement whilst it's happening. I didn't notice any ataxia when I examined her, but I think I'll get her back in to have another look. I think I need to do a repeat thorough exam, with your questions in mind, to see if I've missed anything subtle.

It did cross my mind that this may not be neurological i.e. could there be an ear, eye,nose or mouth issue causing this?

I'll keep you posted.

Re: Odd behaviour-any neurologists out there?

Mark Lowrie — Wed, 22 May 2013 16:19:57 GMT

[quote user="James Laidlaw"]

[/quote]

Hi James,

I really think Pexion should be reserved as a first-line drug for the management of idiopathic epilepsy in dogs – the thing for which it is licensed for.

Re: Odd behaviour-any neurologists out there?

James Laidlaw — Wed, 22 May 2013 15:10:39 GMT

[quote user="Mark Lowrie"]However, as I am not convinced this is a seizure and the presentation is unusual I would not recommend Pexion as there is no hurry to achieve steady state with an anti-epileptic drug and Pexion, given it is a new drug, is far better reserved for routine epileptic patients. I don’t see any advantage to using it here.[/quote]

Mark,

Re: Odd behaviour-any neurologists out there?

Mark Lowrie — Wed, 22 May 2013 08:59:30 GMT

How long do these episodes last? From your description it appears this dog is completely aware during the episode. Do the owners see the episodes start or do they catch the dog during the episode itself? The reason I ask is this could be post-ictal behaviour. There doesn’t appear to be any autonomic signs (e.g. salivation or defecation), the fact that the dog can be distracted out of it and no loss of awareness make a seizure very unlikely. Are there involuntary movements of the limbs (it isn’t clear on the video)? You say the episodes are worsening – do you mean they are more frequent, they are getting longer or they appear to more sever when they happen?

It would seem this is more likely to be some form of movement disorder but if the dog can move around freely during an episode then it would be helpful for the owners to provide a video of an episode showing the dog moving around to see if there is any vestibular ataxia or other abnormalities. I assume the dog is completely normal in between these episodes? No loss of toilet training etc in between.

A phenobarbitone trial would be a sensible cheap approach aiming to get the serum concentration within the mid-therapeutic range if referral is refused. If this reduces the episode by at least 50% then a seizure would seem likely. However, as I am not convinced this is a seizure and the presentation is unusual I would not recommend Pexion as there is no hurry to achieve steady state with an anti-epileptic drug and Pexion, given it is a new drug, is far better reserved for routine epileptic patients. I don’t see any advantage to using it here.

Re: Odd behaviour-any neurologists out there?

tess — Wed, 22 May 2013 00:18:01 GMT

What about trying Pexion? Would it work more quickly than phenobarb?

Re: Odd behaviour-any neurologists out there?

tess — Wed, 22 May 2013 00:15:49 GMT

Sorry forgot to say, triglycerides and cholesterol all normal.

Re: Odd behaviour-any neurologists out there?

David Mills — Wed, 22 May 2013 00:06:41 GMT

Similarly it looks like a localised, partial, mild seizure. However, it could also be cardiac related with that neck movement. I assume it all checks out cardiologically on regular exam, but it could be an intermittent arrhythmia - whilst she's doing it, you could train the o to feel the heart beat fpr rate.

If you want to assess response to seizure meds I'd go with some keppra which has a far quicker (within 24h) response than phenobarb - its more expensive but easier to dose and will be more reliable as a diagnostic trial. If it works and they decline referral, you can always use cheaper phenobarb long term. IME you need a full dose of pheno for partial or full seizures - which I expect is what Mr Mellor meant, but with a starting dose at low end of spectrum.

Re: Odd behaviour-any neurologists out there?

Julie Innes — Wed, 22 May 2013 00:05:28 GMT

Ooh- I just did a webinar tonight where they mentioned familial hyperlipidaemia in Min Schnauzers potentially causing seizure-like activity- possibly worth testing cholesterol and triglycerides?

Re: Odd behaviour-any neurologists out there?

tess — Tue, 21 May 2013 23:16:27 GMT

The owners were undecided about referral when I first suggested it. I suppose if there's no response on trial meds, it would be good grounds for encouraging them to go .

Re: Odd behaviour-any neurologists out there?

Andrew Mellor — Tue, 21 May 2013 18:11:25 GMT

Looks very much like a focal seizure to me but I am no expert, I would suggest MRI if insured or affordable but maybe see if low dose phenobarb will reduce or stop attacks. Bit old to be starting with seizures unless there is some underlying cause.