Myasthenia Gravis Problems

Re: Myasthenia Gravis Problems

Anthony Dennison — Sat, 23 Feb 2013 08:50:44 GMT

Update: the dog was admitted on Thursday for IVFT and supportive care - bloods showed slightly low electrolytes (Na, K, Cl) and mildy raised HCT, likely because of the vomiting.

Food was fed from a height, then she passed a bit of possible toy - bit of rope with material on the end and some foam. went home yesterday much brighter. Looks like it may have been a combination of MG problems and a partial FB, but she has been increased to 30mg BID of mestinon for now

Re: Myasthenia Gravis Problems

Michael Woodhouse — Thu, 21 Feb 2013 10:25:20 GMT

The dog we have is on syrup but it is commercially available from http://www.creopharma.com/about-creopharma

They just emailed us some forms to sign and opened us an account.

Was very painless. Also allows complete dosing flexibility.

The dog we have is a JRT

Re: Myasthenia Gravis Problems

Mark Lowrie — Thu, 21 Feb 2013 09:49:10 GMT

Myasthenia is very difficult to manage. You have been faced with the age old question, are you over or under dosing this dog? In the days of edrophonium (t short acting Ach-esterase inhibitor) you could give this intravenously to see if you observed a transient improvement or deterioration in signs and hence determine whether the dog was over or under- dosed. However, this does not now seem to be widely available.

Over-dosing seems a possibility as you suggest that you have done serial serum Ach antibody titres that are decreasing. This may suggest the disease is resolving and so the dose that did control the signs previously, would now be too high and subsequently result in an over-dose.

Alternatively, this could be an under-dose. For example, if you have a concurrent thymoma or other neoplastic lesion then as this grows, the titre may increase and hence symptoms could potetnially progress.

How is the dog on the increased dose of Mestinon? This may give you an answer to the above – if worse then it was over-dosing, if better then it was under-dosing. A response should be seen within 12 hours.

However, I noticed you changed the dosing from TID to BID. I would be careful with this as it should really be given q8h and so this dog could be doing quite well immediately post pill on q12h dosing but then deteriorate significantly in the few hours before the next pill. Mestinon comes in an awkwardly large pill size (60mg) so splitting is not easy but I frequently find that I have to split the tablets into eighths and increase/decrease in these small increments. The dose of 30mg TID is already quite high although I am not sure what the body weight of the dog is. I tend to start at the very low end of the dose range (0.2 – 5 mg/kg q8h) and increase accordingly – therefore for a 20kg dog this would mean giving 4mg q8h – practically impossible with such a large pill size.

Mestinon can be formulated in a syrup which negates the need to give decreasingly small tablet sizes. This would be a consideration here. Nova Laboratories do this formulation.

The major complication in addition to severe muscle weakness is the risk of aspiration and it sounds likely this dog has already aspirated given the large episode of regurgitation. I would therefore keep a very close eye on this and add antibiotics if even slightly concerned re: asp pneumonia.

Re: Myasthenia Gravis Problems

Anthony Dennison — Wed, 20 Feb 2013 22:22:27 GMT

Thats the drug she's on, name went out of my head (afraid I've contracted carnival cold after my holiday, England is flipping cold! )She's on quite a low dose of mestinon currently and has been on preds, which I think we're currently tailing off. Doesn't help she has been aspirating so gets the occasional problem with pnuemonia like symptoms so is often on antibiotics as well.

Thanks for the advice though, taken on board. Think I might speak to a medic at our nearest referral centre for help when I'm back in on Friday

Re: Myasthenia Gravis Problems

Michael Woodhouse — Wed, 20 Feb 2013 22:13:32 GMT

Way out of my comfort zone here, but we have a MG dog in the practice on Mestinon. When he has flare ups a tailing course of pred and Cerenia settle things down. Not had a problem for a while but he needed some steroids initially to get control.

If on Mestinon but be bloody careful because it is nasty stuff and and OD can look very much like a flare up.