How much domitor to give?

Re: How much domitor to give?

Michael Woodhouse — Fri, 28 Sep 2012 23:22:43 GMT

[quote user="Mark Holmes"]I am in the LOVE domitor camp. Over the years my use has increased and confidence with it. I will use them in dogs with clinically asymptomatic murmurs and the elderly without worry and incidentally my "anaesthetic complications" has (albeit subjectively measured) reduced in tandem.[/quote]

Me too. The simple fact that you can turn it off very quickly with a shot of antagonist actually makes it very, very safe.

I use it as routine pre-med for pretty much everything.

Re: How much domitor to give?

James Allsop — Fri, 28 Sep 2012 18:04:51 GMT

you can always increase the dose of butorphenol - 0.1mg/kg is the listed dose on all the dom/torb charts but the analgesic dose is much higher

Re: How much domitor to give?

Rajat — Fri, 28 Sep 2012 17:06:53 GMT

[quote user="David Mills"]Alpha 2s are poorly understood I think, generally[/quote]

Do you mean to say you understand em better than most?

Do you think they are incapable of harm?

Are they as safe for the aggressive 9 year old geriatric GSD whose heart we may have not listened to for 3 years as the 1 year old bouncy spaniel in for a spay?

I mainly agree with your comments on their physiological effects in the healthy animal (but not for all ages and health statuses acorss the board!). I use it a lot and love its effects for multiple reasons- but hey I love white wine but I know if I drink too much it does bad things to me !

Re: How much domitor to give?

Rajat — Fri, 28 Sep 2012 16:54:09 GMT

[quote user="Mark Holmes"]But if BP is up and blood adequately saturated surely perfusion is adequate even with reduced output.[/quote]

Sorry, this is incorrect, perfusion is not equal to blood pressure!!

Medetomidine causes increases in SVR which leads to higher BP and hence a compensatory reflex drop in HR and CO.

[quote user="Mark Holmes"]Hence if you give dom and Bp increases CO can reduce without harm.[/quote]

This is true in the healthy animal with adequate reserves. Not all aggressive dogs fall into this category, and there is the potential to do harm if the same doses are used and the same logic is applied to all our patients in this manner.

All I was proposing is a way to reduce the potential to do harm (I never said it will definitely do harm) - by usijng a combination of drugs that together may be less harmful than massive doses of medetomidine.

Incidentally, I am a big medetomidine fan and prob use it the most in our 8 vet pracice!

Re: How much domitor to give?

Mark Holmes — Fri, 28 Sep 2012 16:34:29 GMT

[quote user="David Mills"]

[quote user="Mark Holmes"]

[quote user="Rajat"]is evidence that even at very low doses (2-5ug/kg) there are substantial (40-50% from memory) reductions in cardiac output.[/quote]

How much of that is a primary depressant effect on cardiac output and how much is that a physiological reaction to needing less cardiac output as you are sedated

There is a 50% reduction in cardiac output when I get of my bike and sit on the sofa yet it is not harmful.

[/quote]

Indeed. One of the major effects is attenuation of sympathetic overdrive seen in clinics.

Alpha 2s are poorly understood I think, generally. Central arterial pressure changes little even with high doses - the vast majority of blood pressure effects are peripheral, and perfusion is maintained to central organs. Sure things go white and HR drops but so what? Respiration drops but oxygen tension is maintained and increased depth of resp occurs. They are truly one of the safest sedatives around. The 'do harm' camp is, unfortunately, a dogmatic approach, I think heavily influenced by their promotion as a 'heavy sedative' = fear! They must do bad things!

[/quote]

I am in the LOVE domitor camp. Over the years my use has increased and confidence with it. I will use them in dogs with clinically asymptomatic murmurs and the elderly without worry and incidentally my "anaesthetic complications" has (albeit subjectively measured) reduced in tandem.

Re: How much domitor to give?

Mark Holmes — Fri, 28 Sep 2012 16:30:54 GMT

[quote user="Rajat"]

It is a reduction from 'base' cardiac output due to reduction in cardiac contractility tho BP does go up, CO is down.

When you are on your bike you are exerting yourself, so your CO is supra physiological compared to rest- your muscles need it.

When you are on your sofa, you are at rest and your CO is adequate for that. If your CO dropped by half then you'd be pretty weak and find the gentlest fo exertions very difficult.

Now add to that potential underlying co morbidities and organs which may not have adequate perfusion with a 50% drop in CO - could lead to trouble. Not saying it will neccessarily, just I prefer a different strategy which may be safer.

[/quote]

But if BP is up and blood adequately saturated surely perfusion is adequate even with reduced output. As I understood it cardiac output supports blood pressure supports perfusion. As in its not the output per se which results in perfusion but the blood pressure that results from output.

Hence if you give dom and Bp increases CO can reduce without harm.

Re: How much domitor to give?

David Mills — Fri, 28 Sep 2012 16:30:30 GMT

[quote user="Rajat"]

It is a reduction from 'base' cardiac output due to reduction in cardiac contractility tho BP does go up, CO is down.

When you are on your bike you are exerting yourself, so your CO is supra physiological compared to rest- your muscles need it.

When you are on your sofa, you are at rest and your CO is adequate for that. If your CO dropped by half then you'd be pretty weak and find the gentlest fo exertions very difficult.

[/quote]

The 'base' cardiac output is a falsity though - a starting point of shifting sand because it depends a lot on 'stress'/SNS activity; we've all seen dogs that need a lot more than originally thought if they're manic.

The CO is a surrogate endpoint with no direct, predictable correlation to target organ damage; it remains purely theoretical as far as I'm aware.

Re: How much domitor to give?

David Mills — Fri, 28 Sep 2012 16:27:30 GMT

[quote user="Mark Holmes"]

[quote user="Rajat"]is evidence that even at very low doses (2-5ug/kg) there are substantial (40-50% from memory) reductions in cardiac output.[/quote]

How much of that is a primary depressant effect on cardiac output and how much is that a physiological reaction to needing less cardiac output as you are sedated

There is a 50% reduction in cardiac output when I get of my bike and sit on the sofa yet it is not harmful.

[/quote]

Indeed. One of the major effects is attenuation of sympathetic overdrive seen in clinics.

Re: How much domitor to give?

Rajat — Fri, 28 Sep 2012 16:25:15 GMT

It is a reduction from 'base' cardiac output due to reduction in cardiac contractility tho BP does go up, CO is down.

When you are on your bike you are exerting yourself, so your CO is supra physiological compared to rest- your muscles need it.

When you are on your sofa, you are at rest and your CO is adequate for that. If your CO dropped by half then you'd be pretty weak and find the gentlest fo exertions very difficult.

Re: How much domitor to give?

Mark Holmes — Fri, 28 Sep 2012 16:18:07 GMT

[quote user="Rajat"]is evidence that even at very low doses (2-5ug/kg) there are substantial (40-50% from memory) reductions in cardiac output.[/quote]

How much of that is a primary depressant effect on cardiac output and how much is that a physiological reaction to needing less cardiac output as you are sedated

There is a 50% reduction in cardiac output when I get of my bike and sit on the sofa yet it is not harmful.

Re: How much domitor to give?

Rajat — Fri, 28 Sep 2012 16:09:35 GMT

[quote user="David Mills"]

Remember it is really, really, really, difficult to kill something with domitor. For aggressive dogs we use 1ml/10kg, have doubled it in the past/topped up.

If you can get roughly IM, another possibility is alfaxan IM at non-premedicated doses. Drops 'em like a stone.

[/quote]

Hmm it may be difficult to kill but maybe not difficult to do harm. There is evidence that even at very low doses (2-5ug/kg) there are substantial (40-50% from memory) reductions in cardiac output.I have never used such high doses I think the most I have given is 1.2 ml to a 50kg dog!

It is much safer to use polypharmacy and for these aggressive dogs, ketamine is our friend (as the OP found out!)

I prefer mixing Medetomidine at 30-40ug/kg, midazolam .25mg/kg butorphanol .3mg/kg and ketamine 5-10mg/kg. Never fails to work!

Alfaxan is another decent option IM

Re: How much domitor to give?

Martin Atkinson — Fri, 28 Sep 2012 15:18:18 GMT

[quote user="CatherineThomas"]He can get a muzzle onto her but she manages to get it off every time when she sees a vet coming towards her[/quote] May I suggest a correctly fitting muzzle? It is not a proper Rotty muzzle on tight enough it will get it off. Owners who have the muzzle too loose and make no attempt to stop the dog pawing it off get my goat in the same league as those who have the collar too loose and the dog pulls out of it, or let their cat keep jumping off the table or allow it back in the basket so its another fight to get it out

Re: How much domitor to give?

CatherineThomas — Fri, 28 Sep 2012 13:33:37 GMT

The owner is actually a really lovely older man who is very co-operative and understands that the dog needs sedation to be able to be treated. He says she is fine at home and it is just vets she doesn't like. He can get a muzzle onto her but she manages to get it off every time when she sees a vet coming towards her. He was quite happy to pay for everything to be done and seems like a responsable owner. She was actually ok to get the injections in while a nurse held the lead the other side of the door.

We gave her a little ketamine and that did the trick.

Re: How much domitor to give?

Clive Ansell — Fri, 28 Sep 2012 13:12:22 GMT

Most colleagues, practices and practice owners I know would be of the same opinion and fully supportive, safety has to come first.

Rightly or wrongly I am becoming less tolerant of idiots with large, aggressive, unsocialised and unhandleable dogs. My job is to exam their animal, it is up to them to present it under control with a muzzle placed if requested. If I wanted to be a lion tamer, I would go and do it .

I did once have a practice owner email and complain following a client complaint that I couldn't/wouldn't (I did try) give her aggressive cat a worm tablet. She was offered profender and refused it. Practice owner offered her a free consult to give tablet saying "he's just a locum and probably couldn't be bothered" (It's always reassuring that colleagues are 100% behind you in the face of difficult clients ) he finished up getting bitten and needing antibiotics, and still didn't give the tablet. Idiocy, and a completely unnecessary risk - cat bites being potentially serious and all that.

Re: How much domitor to give?

Martin Atkinson — Fri, 28 Sep 2012 12:38:01 GMT

[quote user="Clive Ansell"]I would not accept the case unless it was muzzled by the owner, my safety and that of the owner and other staff are the the paramount priority. In fact I gave marching orders to the braindead owners of an aggressive GSD last night that they could not control or place a muzzle.[/quote] My policy is the same and I would be fully supportive when you are working for me but how do the owners of other practices you work for generally accept this Clive?

Re: How much domitor to give?

nikki — Fri, 28 Sep 2012 11:42:06 GMT

i usually go for the top up of ketamine when dom/torb hasn't worked. decent dose seems to eventually get them to go sleepy.

Re: How much domitor to give?

David Mills — Fri, 28 Sep 2012 11:36:48 GMT

Remember it is really, really, really, difficult to kill something with domitor. For aggressive dogs we use 1ml/10kg, have doubled it in the past/topped up.

If you can get roughly IM, another possibility is alfaxan IM at non-premedicated doses. Drops 'em like a stone.

Re: How much domitor to give?

Clive Ansell — Fri, 28 Sep 2012 11:27:39 GMT

I would not accept the case unless it was muzzled by the owner, my safety and that of the owner and other staff are the the paramount priority. In fact I gave marching orders to the braindead owners of an aggressive GSD last night that they could not control or place a muzzle.

I have used dom/torb with acp before which was very effective. 0.1ml Torb, 0.25 Dom and 0.3 2mg/ml ACP per 10 kg. I would repeat the dose if necessary, but warn the owners that it could be dangerous as the maximum has been given already. If full anaesthesia is needed I would give 0.5 ml/10kg ketamine 20 min later.

I have used large amounts of Dom/Torb/Ket/ACP in the same syringe for sedating dogs that are going to be PTS anyway, even with massive and unmeasured doses I have never seen one die from it.

Should this dog be PTS?

Re: How much domitor to give?

Mark Hedberg — Fri, 28 Sep 2012 10:15:04 GMT

http://www.noahcompendium.co.uk/Pfizer_Limited/Ketaset_100_mg_ml_Solution_for_Injection/-35894.html (Ketamine has a great dose chart in it, just for reference.)

For a 10kg dog:

0.1ml Torbugesic (10mg/ml solution)

0.25ml medetomidine (1mg/ml solution)

wait 15 minutes:

0.5ml ketamine (100mg/ml solution)

Don't know how big your dog is but the full dose chart is in the above link.

Cheers,
Mark

Re: How much domitor to give?

Mark Holmes — Fri, 28 Sep 2012 10:11:15 GMT

Give LOTS, I once had a calculation failure and gave 20kg dose to a 2kg dog. Domitor people said "So what" or words to that effect. They said it has a ceiling of effect when all receptors are bound and oer dose just results in longer sedation, which provided you always reverse with the same amount is irrelevant. So the dog got a 20kg dose of antisedan as well!

You could also give some ketamine im if not getting anyehere

Re: How much domitor to give?

Martin Atkinson — Fri, 28 Sep 2012 10:11:05 GMT

Notwithstanding my thoughts that I wouldn't be seeing such an aggressive dog if the owner cant muzzle it, it may depend on where you got the injection if indeed you're confident you hit a moving target in the first place and if the amygdala is in full ascendency then it may need a higher dose. Also if it went into the intra-muscular fascia it may have poor uptake. If I was committed to this then I would repeat the dose as often as necessary if it still fully concious, maybe as suggested with some ketamine. Warn the owners it is at their risk but it takes what it takes, you're unlikely to kill it just have the Antisedan ready.

Re: How much domitor to give?

CatherineThomas — Fri, 28 Sep 2012 09:49:47 GMT

We weighed it a couple of days ago. Although it was moving around a bit so I'm not sure it's completely accurate but it is roughly right. how much ketamine would you give?

Re: How much domitor to give?

Mark Hedberg — Fri, 28 Sep 2012 09:46:13 GMT

Have you been able to get an up to date weight? It's quite possible the dog is simply heavier than you expect; even if the owner swears it's weight X, it's hard to tell without a scale. You could be underdosing.

You might have to 'bite the bullet' and give ketamine to give a triple anaesthesia.