Medetomidine and heart disease.

RE: Medetomidine and heart disease.

Clive Ansell — Wed, 21 Sep 2022 07:46:01 GMT

[quote userid="11901" url="~/001/veterinary-clinical/small-animal/cardiology/f/discussions/30417/medetomidine-and-heart-disease/239217#239217"]I have wondered if the aversion to GA is sometimes less about the murmur and more an aversion to doing those smelly, frustrating, “expensive” dentals…[/quote]

I'm convinced that it is an aversion to spending money.

I see cases most days of albeit older, outwardly healthy animals, no murmurs etc, that need dental work but the owners just will not pay for it. They begrudge spending between £350 - £500 on their pet, that is "part of the family" and which they would "do anything for"

I saw an old Westie yesterday with what looks like a malar abscess and severe dental disease. These guys were advised 5 years ago that the dog need dental work. Neglect and they ought to be prosecuted.

RE: Medetomidine and heart disease.

Miriam Lodewyks — Tue, 20 Sep 2022 09:03:31 GMT

Thank you Dave.
Those were my thoughts too, good to get pragmatic advice from the ivory tower…

I have wondered if the aversion to GA is sometimes less about the murmur and more an aversion to doing those smelly, frustrating, “expensive” dentals…

RE: Medetomidine and heart disease.

Dave Dickson — Mon, 19 Sep 2022 17:06:13 GMT

[quote userid="11901" url="~/001/veterinary-clinical/small-animal/cardiology/f/discussions/30417/medetomidine-and-heart-disease/239195#239195"]@ Dave Dickson: what are your thoughts on dental disease (peridontitis and low-grade septicaemia) vs. Anaesthetic drugs when it comes to exacerbating cardiac disease?[/quote]

Hi GrooveJet

My thoughts are that I think dental disease is nearly always a far bigger influence of QOL than mitral valve disease (excepting advanced heart failure). I spend a lot of time encouraging owners (and vets) to do dentals - in fact today I had a CKCS with mitral valve disease, stable CHF and absolutely terrible teeth (I pulled out a loose, rotten premolar in the consult room) because the vets had been too worried about GA in this dog since she developed a murmur, several years ago. Which has left her with a terrible mouth now that is much risker to manage.

I don't see much endocarditis, but what I do see is nearly always in dogs with aortic stenosis. Despite concerns about dental disease causing endocarditis in dogs with mitral valve disease, I don't think it's really a thing - if you work out how many dogs with mitral valve disease also have bad teeth (many/most of them) and compare that to the number of dogs with mitral endocarditis, the comparison just doesn't stack up. I'm not saying it never happens, but it is vanishingly rare.

So if I have to make a choice between keeping the heart "safe" or fixing the teeth, I always choose teeth. Mitral valve disease copes fine with anaesthesia (provided they aren't in CHF) and the dog will feel better for having loose, rotten and infected teeth removed.

Provided the patient is assessed carefully prior to GA - and that may mean just a good history and a thorough clinical exam - not every dog needs an echo prior to GA ;) - then I'm usually happy to go ahead.

Hope that helps

RE: Medetomidine and heart disease.

Dave Dickson — Sun, 18 Sep 2022 21:45:31 GMT

Exactly. What is a nuanced, case-by-case decision making process has become an us-vs-them argument about who thinks Alpha-2s are safe or not.

This will go back and forth as ultimately, it's a pointless argument. Medetomidine is undoubtedly safe in a lot of patients, if used wisely.

RE: Medetomidine and heart disease.

Evelyn Barbour-Hill — Sun, 18 Sep 2022 21:21:38 GMT

I'm not remotely an expert in these things. Feel free to laugh me down, but should we not make a distinction in this context between on the one hand the tiny dose used as a premedication, to reduce markedly the dose of induction agent and to some extent the necessary dose of maintenance agent; and on the other hand the much larger doses used for sedation or deep sedation or with ketamine for anaesthesia?

RE: Medetomidine and heart disease.

Dave Dickson — Sun, 18 Sep 2022 20:53:41 GMT

Clive Ansell said:

I have worked with three RCVS anaesthesia certificate holders, and one RCVS diplomat holder and recognised specialist in anasesthesia, all of whom use Medetomidine.

Not surprised. Safe. Reversible. Excellent multimodal analgesic.

all true. I too work with Specialists who use it. But not routinely in patients with significant cardiac disease, which was the original question :)

Dave

RE: Medetomidine and heart disease.

Michael Woodhouse — Sun, 18 Sep 2022 20:16:18 GMT

[quote userid="5012" url="~/001/veterinary-clinical/small-animal/cardiology/f/discussions/30417/medetomidine-and-heart-disease/239196#239196"]I have seen Medetomidine used many times by colleagues (Purely an observation and not a critisism in any way whatsoever) in cases where it would not be my first choice; sick and old patients, those with cardiac disease, very heavy sedation for minor mass removals with no supplementary O2 with cyanotic mm etc. I don't know of any that have died or gone mammaries up. [/quote]

This is one of those things i hear when people don't understand the drug. Peripheral vasoconstriciton does make them pale/mild cyanosis, but maintains important central pressure (CF ACP where they look lovely and pink with BP through the floor).

[quote userid="5012" url="~/001/veterinary-clinical/small-animal/cardiology/f/discussions/30417/medetomidine-and-heart-disease/239196#239196"]We were taught at university (Liverpool 1996) that Medetomidine was the drug of Satan and should be entirely reserved for aggressive animals were there is no other choice.[/quote]

I agree (RVC 2006) but back then they ignored cascade and used some interesting combinations. I've never seen so many animals wake up during surgery from the anaesthetics done at college by anaesthetists.......

[quote userid="5012" url="~/001/veterinary-clinical/small-animal/cardiology/f/discussions/30417/medetomidine-and-heart-disease/239196#239196"]I have worked with three RCVS anaesthesia certificate holders, and one RCVS diplomat holder and recognised specialist in anasesthesia, all of whom use Medetomidine. [/quote]

Not surprised. Safe. Reversible. Excellent multimodal analgesic.

RE: Medetomidine and heart disease.

Evelyn Barbour-Hill — Sun, 18 Sep 2022 13:15:16 GMT

We were taught at university that you could not give an opiate to a cat as it would send it manic.

RE: Medetomidine and heart disease.

Clive Ansell — Sun, 18 Sep 2022 07:50:37 GMT

I forgot to add in my earlier post.

I have seen Medetomidine used many times by colleagues (Purely an observation and not a critisism in any way whatsoever) in cases where it would not be my first choice; sick and old patients, those with cardiac disease, very heavy sedation for minor mass removals with no supplementary O2 with cyanotic mm etc. I don't know of any that have died or gone mammaries up.

We were taught at university (Liverpool 1996) that Medetomidine was the drug of Satan and should be entirely reserved for aggressive animals were there is no other choice.

I have worked with three RCVS anaesthesia certificate holders, and one RCVS diplomat holder and recognised specialist in anasesthesia, all of whom use Medetomidine.

RE: Medetomidine and heart disease.

Miriam Lodewyks — Sat, 17 Sep 2022 17:59:37 GMT

Dave Dickson what are your thoughts on dental disease (peridontitis and low-grade septicaemia) vs. Anaesthetic drugs when it comes to exacerbating cardiac disease?

RE: Medetomidine and heart disease.

Miriam Lodewyks — Sat, 17 Sep 2022 17:51:32 GMT

Thank all, that’s really really helpful information.
Of course we’d all love to provide each and every case with “gold-standard” care, but I’m long enough in the tooth to understand that that’s just never going to be practical in day-to-day practice.
What is good to know is what ivory tower we should be aiming for (thanks Dave Dickson).
What’s reassuring is hearing that many of my “coalface” colleagues are doing what I do: making the best judgement you can given the information and resources at hand.

What’s hard sometimes is convincing one owner that their perfectly bouncy spaniel really needs a heart work up before we xray that stifle, and then convincing the next client that their Yorkie needs that GA regardless or else it’s mandibles will disintegrate entirely…

RE: Medetomidine and heart disease.

Clive Ansell — Sat, 17 Sep 2022 07:50:47 GMT

[quote userid="6877" url="~/001/veterinary-clinical/small-animal/cardiology/f/discussions/30417/medetomidine-and-heart-disease/239160#239160"]I’d only ever use detomidine in a cardio patient that ‘you can’t get near’ due to aggression etc (cardiology cert holder with previous 20 years as a GP). There are better options for most patients IMO. [/quote]

I think you've hit the nail on the head.

My prefered premed or sedation in dogs is Medetomadine and Methadone, but is decided on a case by case basis. I don't like the idea of "standard anaestheetic" or anaesthetic protocols.

The data sheets for Medatomidine say to exercise caution in any unwell patients, and those with cardiovascular disease. I therefore look for alternatives depending upon the case. In the event of something going wrong, we would all have to be able to justify its use.

Where I am currently working we see a lot (at least 3 or 4 a day) of very aggressive dogs. These cannot be examined or assessed in detail for any underlying anaesthetic risks and need full data sheet doses of Medatomidine and an opiate to drop them down. Some have been preloaded with Trazadone and Alprazolam too. Never had one go wrong yet, and some have been found to have heart murmurs once anaesthetised.

Similarly, we see many feral and semiferal cats presented by resuce centres for neutering. Many are too fractious to be examined or properly assessed and will be given Medetomidine in a crush cage. I prefer the quad combination using methadone, very low doses and very effective, although there is confusion in some practices in the interpretation of the cascade regs and the use of Midazolam.

RE: Medetomidine and heart disease.

Clive Ansell — Sat, 17 Sep 2022 07:35:03 GMT

[quote userid="3169" url="~/001/veterinary-clinical/small-animal/cardiology/f/discussions/30417/medetomidine-and-heart-disease/239185#239185"]I'm betting you don't see many elephants........[/quote]

I've never had in 26 years as a vet a single anaesthetic death in an elephant.

RE: Medetomidine and heart disease.

Michael Woodhouse — Fri, 16 Sep 2022 22:37:16 GMT

[quote userid="14690" url="~/001/veterinary-clinical/small-animal/cardiology/f/discussions/30417/medetomidine-and-heart-disease/239180#239180"] Probably comes from spending too long looking out of the window of my ivory tower [/quote]

I'm betting you don't see many elephants........

RE: Medetomidine and heart disease.

Dave Dickson — Fri, 16 Sep 2022 17:09:29 GMT

Right, a good example. And a common one.

Older, small breed dogs, like Cava-crosses etc, with soft (grade 1-2) left apical systolic murmurs nearly always have mild mitral regurgitation. The chances of it not being DMVD are very small, as long as you are wary of Cockers and (in my experience) Staffies, who can get DCM and these usually have soft murmurs. We know, from large studies, that this group of dogs with soft murmurs almost never have significant heart enlargement, meaning there is no increased anaesthetic risk from a cardiac perspective.

Therefore, for the patient you describe, I'd have no worries about anaesthetic and (I get asked this a lot) I'd use whatever anaesthetic protocol you are most comfortable with. Personally, and this is probably just my bias, I wouldn't use Domitor, but I wouldn't say "don't". And I certainly don't think you are at significant risk of pushing these dogs into CHF with Domitor. If it were my GA, then I'd use an opiate (methadone if a dental) plus midazolam premed, followed by alfaxan. Ideally I'd do a CRI with alfaxan, as that is what I do and am most familiar with it. However I appreciate the cost concerns so maintain with whatever you normally do. For dentals (and other painful procedures) I'd use local blocks to minimise surgical stimulation (as pain is bad for the heart too) and to help minimise isoflurane doses (as this is a very cardio depressive agent).

If you asked 10 cardiologists for a protocol for this type of patient, I expect you'd get 10 ways of doing it. And if you asked 10 anaesthetists you'd get another 20 ways of doing it ;)

Bottom line for me - assess the risk carefully prior to anaesthesia, which it sounds like you are doing. And never withhold dental treatment from a dog with mild mitral valve disease - the rotten teeth are much more of a welfare issue than a mild leak in a valve. Believe it or not, I spend a lot of my time convincing vets to anaesthetise dogs with mild mitral valve disease. I just want to move the discussion away from the :"cardiac GA protocol" - this is one of my pet peeves. Probably comes from spending too long looking out of the window of my ivory tower

Dave

RE: Medetomidine and heart disease.

Sean Dunne — Fri, 16 Sep 2022 15:52:38 GMT

Dave .. the one that comes up the most here is an outwardly lively small breed mix Cava something or other that has a Grade 1-2 murmur. Most won't go for scanning and to be honest we do use Domitor in these cases(5ug/kg im). We discuss the ASA classification & explain our heretofore experience of most doing well.

This conversation does mean some risk averse and cash poor folks get stuck in a limbo and decide best action is no action. This leads to some useful & beneficial work not getting done leaving all concerned a bit fed up ... Us client & dog.

I would be keen to be able to offer a more MVD friendly protocol ... I am of course assuming all these little patients have MVD which in itself is only an educated guess.

RE: Medetomidine and heart disease.

Arlo Guthrie — Fri, 16 Sep 2022 13:37:50 GMT

[quote userid="14690" url="~/001/veterinary-clinical/small-animal/cardiology/f/discussions/30417/medetomidine-and-heart-disease/239159#239159"]Though I think the ivory tower comment is perhaps a little strong,[/quote]

I would tend to agree.

So often I hear GPs stereotyping specialists or what they say as 'ivory tower', and yet most specialists I speak to seem anything but. Most I speak to are only too aware of the selective cases they see and the way it can skew their opinion.

Plus I think 'Ivory Tower' is somewhat pejorative term, although I am not entirely sure how else you could word it.

RE: Medetomidine and heart disease.

Dave Dickson — Fri, 16 Sep 2022 13:28:03 GMT

Hi Sean

Not a basic question at all. You need to give me some case particulars to answer that - dog/cat? old/young? murmur?

RE: Medetomidine and heart disease.

Sean Dunne — Fri, 16 Sep 2022 13:19:13 GMT

Dave. Forgive a basic question. What would your preferred pre med be in a case where a diagnosis could not be reached .... What drug combination is a decent stab at "safest" when we don't know what we don't know heart wise ?

RE: Medetomidine and heart disease.

Dave Dickson — Fri, 16 Sep 2022 12:25:00 GMT

I think, like with all things anaesthesia, it totally depends on context. Each case is different and whilst a drug might be safe in one situation, it won't be in another. Ketamine is great, but I'd never use it in a cat who is in or on the edge of CHF - I've had some crash immediately post ketamine which I assume is the tachycardia it drives. However one of my colleagues uses it (carefully) without problems.

I've worked with anaesthetists who love alpha 2's and others who don't use them much - all with good reasons.

My point all along has been that we can't just lump all cardiac conditions into one category and apply a "GA protocol" or decide if drugs are safe or unsafe. It totally depends on each case.

Dave

RE: Medetomidine and heart disease.

Richard Carter — Fri, 16 Sep 2022 10:40:27 GMT

I thought there had been some work that suggested low dose sedation with alpha 2 had improved outcomes for trauma patients ( rta etc) although I do recall a time (late 90’s) when alpha 2 was really not recommended for ga scenarios - some of the practices I’ve been to recently use it as routine premed.

Am aware ketamine used in human trauma first aid on the basis it supports cardiac and respiratory function

RE: Medetomidine and heart disease.

Arlo Guthrie — Fri, 16 Sep 2022 09:57:05 GMT

Kathryn Garven first post ... welcome!

RE: Medetomidine and heart disease.

Kathryn Garven — Fri, 16 Sep 2022 05:17:59 GMT

I’d only ever use detomidine in a cardio patient that ‘you can’t get near’ due to aggression etc (cardiology cert holder with previous 20 years as a GP). There are better options for most patients IMO.

RE: Medetomidine and heart disease.

Dave Dickson — Thu, 15 Sep 2022 23:10:56 GMT

Michael, some fair comments. Though I think the ivory tower comment is perhaps a little strong, but I’ll forgive you as it’s late.

[quote userid="3169" url="~/001/veterinary-clinical/small-animal/cardiology/f/discussions/30417/medetomidine-and-heart-disease/239157#239157"]Some people will take from that reply that medetomidine is not safe in animals with heart disease and then it becomes enshrined in vet folklore and passed on.[/quote]

Only people who can’t read to the end of a post, surely?

I don’t think my case example is a freak case. It wasn’t a drug reaction, overdose or other mishap. It was an inappropriate use of a drug given to a patient in whom heart disease had been missed/ignored. That’s my point - you can’t just assume all heart disease is the same, as you imply in your first post, and adopt the approach “I’ve always got away with it, so it’s fine”. Forgive me, but that isn’t a great approach to medicine.

If you have an owner with a dog and you say “there’s a heart murmur, it could mean bad heart disease but I think it’s unlikely, however there is some risk to (all) sedation so I think we should take these steps… it’s up to the owner to decide what to do. They don’t want the echo - fine, it’s their risk. Big risk? Probably not, no, I agree with you. Should you warn them of the risk? And at the same time, consider your GA plan carefully? I think so.

To lump all heart disease into one category and manage it as if it’s fine because you’ve always got away with it is reductive and, in my opinion, poor advice.

I’ve given the OP some specific conditions where I think medetomidine in particular needs to be considered carefully.

In the 10,000 healthy dogs, I agree it’s a safe drug. Healthy is the important word there

Now I’m happy to be shot down as a head-in-the-clouds, ivory tower Specialist who has long since lost the memories of life in practice and is only interested in doing things perfectly, or not at all ;)

Dave

RE: Medetomidine and heart disease.

Dave Dickson — Thu, 15 Sep 2022 22:57:22 GMT

GrooveJet to answer your specific question:

“Can anyone advise when I really should NOT be using this drug, and are there any papers I can swat up on to help decide when it is/isn’t appropriate to use Medetomidine for chemical restraint. “

I’d say avoid it when there is significant risk of CHF, systolic dysfunction (ie DCM in dogs, pleural effusion in cats, end-stage mitral valve disease), arrhythmia (especially bradyarrhythmia), pulmonary hypertension or congenital cases, simply because congenitals have a risk of being complex and if there is something bad like a right to left shunt, dropping systemic pressure is a very bad idea.

There are quite a few papers showing medetomidine is safe in various circumstances, not many I know of showing it is unsafe - partly because people who make drugs don’t often publish negative findings and anaesthetists tend to avoid using drugs when they know it’s a bad idea, or set out to publish what drugs are dangerous in specific circumstances.

That’s my view, I’d be interested to hear others - likely to be a lot of robust opinions rather than good evidence I suspect (mine included!).

Dave