Good evening everyone, and thank you for joining us for tonight's BCVA. Webinar. My name is Sarah Peterson from the BCVA board, and I'll be chairing the webinar tonight.

Our speaker Gayle is happy to remain online for questions. So please type any that you may have in the Q&A box during the webinar and I'll save your questions for the end of her presentation. If you have any technical difficulties, then please let us know what problems you may be having by using the chatbox, and we'll do our best to assist you.

Please note that we cannot respond to raised hands, so please use the Q&A or chat boxes. If you can't see them, then if you wiggle your mouse, the taskbar should become visible at the bottom of the screen. So I'm delighted to introduce Gail Halliwell as tonight's speaker.

Gayle graduated from the University of Cambridge in 2002 and went on to complete a large animal internship and dual internal medicine and critical care residency. She then moved up to the School of Veterinary Medicine at the University of Nottingham to complete a PhD investigating the aortic valve in horses. She is currently a professor in veterinary internal medicine and critical care up at Nottingham, where she still undertakes clinical work 60% of her time, working at several different practises.

Her particular interests are in large animal anaesthesia, analgesia, fluid therapy, ultrasonography, and internal medicine. So we're really looking forward to, to Gayle sharing all of her knowledge and experience with us tonight on our topic, which is anaesthesia of farm animals and camelids. Thank you very much, and over to you, Gail.

Thanks very much, Sarah, and thank you for inviting me to talk this evening on one of my favourite topics. So I'm just gonna share my presentation. Hopefully everyone can see that and they can hear me.

So, I thought before I got into sedation and general anaesthesia, I thought I'd just remind everybody about the triad of anaesthesia. So we've got hypnosis or unconsciousness, we've got analgesia, and we've got mus. So relaxation and actually as farm vets we struggle with actually quite a few of these different corners of this triangle.

So in terms of the plan for this session this evening, I'm gonna very briefly touch on analgesia, which is obviously a, a whole 45 minute talk by itself, but, Just wanted to bring up a, a few points. And then we're gonna touch on some of the sedatives that we've got available and some of the challenges that we've got, not least not having MRLs for our food producing animals. And then I'm gonna move on to talk about general anaesthesia, the procedure of general anaesthesia, and the similarities and some of the challenges compared with other species that you, might still anaesthetize or have anaesthetized in the past.

And then we're gonna talk about some of the drugs that we can use for, anaesthesia. Induction. So I did a talk actually for some human anaesthetists about 6 weeks ago, and I was talking actually about veterinary anaesthesia, not just the anaesthesia of farm animals, and they were pretty horrified at the limited drugs that we have got available for the types of surgeries that we do.

But actually, although they're, they're, they were horrified, actually we do a pretty Great job with the very few drugs that we have got, that are licenced. So, one thing that we are definitely not lazy at doing is using effective local anaesthetic blocks. And it's always worth remembering that local anaesthetics are the only drug that we've got that actually blocks transmission of pain.

All of the others simply modify how the body, Detects that pain either within the spinal cord or in the brain, and obviously procaine is the drug that we have that's like. Licenced. And then we've got non-steroidals, and we've got several licenced non-steroidals, both for parental and poor on use.

It's also just worth remembering that oral non-steroidals are very well absorbed from the rumen and C1. Of South American camelids. There was some work done at the RVC in the 1990s that never really made it into the general press, that actually absorption of the traditional non-steroidals that we've got is somewhere around.

90%. So for animals that we might be managing that have got chronic pain or that for whatever reason, you might have smallholders that are unable or unwilling to inject animals, oral drugs can certainly be of benefit. The other drug that I think we may be overlook is paracetamol, and paracetamol is licenced for use in pigs, and the EMEA states that because it's rapidly metabolised, that the MRLs are not required for this.

And again, work was done on paracetamol in ruminants in the 90s, very well absorbed from the rumen. And studies in other species show that actually paracetamol can be equivalent. In some scenarios of acute pain and can be just as good as as opioids.

So it's something I think we maybe haven't done enough evaluation or use of in, in ruminants. And the problem is it's not something that's very fashionable to use in veterinary species in North America, which is where a lot of the analgesia and anaesthesia research is undertaken in ruminants. And then obviously, everything else that we use where analgesia's concerned, unless we're thinking about cold things, hot things, acupuncture, stabilisation of limbs, is use without without MRLs.

And I'm going. We're gonna come back and talk a little bit about butterphenol as a sedative, but remember it's a very, very poor analgesic. We've got buprenorphine licencing horses, although we don't have MRLs available for food producing horses.

So, let's move on to to talking about the sedatives that we've got and probably the sedative that we're all most familiar with using is going to be the is gonna be the . Sorry, I, someone's answered the questions from the panel. The first sedative that I'm gonna talk about is going to be xylazine, which is the one that most of us are gonna be familiar with, and it's always bad to start a slide with something as negative as the word death.

However, death has certainly been reported in balls with, intravenous xylazine use. And depending on the brand of xylazine that you use, depends upon whether or not. It's licenced.

There is one formulation of Xylazine that is licenced for IV use, but all of the others are not. And it certainly needs to be administered with care. And it might not be the Xylazine being given IV that's the problem.

It might be that it's in fact, we're inadvertently giving it via intraarterial administration, which is pretty easily done when we're using the coccygeal vein. And the problem with Xylazine compared to the other alpha 2 agonists is Xylazine is quite like a local anaesthetic in its structure, which means it does pretty crazy things when you put it in the artery and it has a main line straight into the brain. If you are using it IM, you definitely need to increase the dose.

It's normally somewhere between 2 to 3 times what you have would have given, IV. And we're gonna talk about some of the problems that we sometimes face when we're sedating, when we're sedating our patients. The other challenges with Xylazine is there's been work done showing that it can cause, myometrial contractility and it can act a little bit like oxytocin.

So, again, everyone's always very cautious, but care with its use in the first and last trimester of pregnancy is certainly warranted if you're not trying to induce pregnancy. The other problem that you have, and I'll show you some some images of what happens with, to respiratory function when we administer xylazine to ruminants, is it seems to cause significant ventilation perfusion mismatch, even in standing animals. So that can be a problem if You anaesthetize them and you tip them over, but it certainly can be a problem when we've got, when we, we administer this drug to ruminants that have already got respiratory disease.

And we know that the lung capacity in ruminants because of the size of their four stomach is already on the edge of what they need, now. And Xylazine, just like the other alpha 2s, can have significant cardiovascular effects, which isn't a problem if you're healthy, but is a big problem if you're dealing. With hypovolemic ruminants or ruminants that have are in shock.

The, the other challenges we've got are. Yeah . Regurgitation leading to aspiration pneumonia can occur, and again that's more likely anti and certainly a change.

Consistently, at least there's something that you know is gonna happen. And then because of these changes in GI motility patterns and presumably changes in the ruminal microbiome, we we can see diarrhoea and that's pretty pretty common 12 to 24 hours after sedation. And if you are dealing with, animals, which are usually gonna be goats, but not always, that have got urethral obstruction, remember that zylazine and the other alpha 2s, suppress anti-diuretic hormones, so ultimately they increase.

Increase urine output. So that's not a problem as long as you get on and unblock them, or at least, do cystocentesis if we're thinking about goats, after, after administration, although I might not use thylazine in a goat, so we'll come to that in a little while. When we think about Diomidine, ditomidine has had a licence now in cattle.

When I talk to people, and it'll be interesting to see what people put in the chat about their use of ditomidine, and people don't seem to, if they. Sedate cattle, they still seem to prefer xylazine over ditomidine, and the, although cattle compared to horses are very sensitive to xylazine, the ditomidine dose is very similar to what you would give to an equivalent weight of horse. It has similar effects to xylazine, but it has a slightly longer duration of action.

And I would say at lower doses, they are less likely to become recumbent, but, again, when you, when you, we did a survey a long time ago, of farm vets using domidine and that perhaps was not their, not their experience. It probably from the data that we've got, it does increase myometrial contractility, but it seems to, be less alignant cattle, which is, is definitely a difference to the small studies that we've got that have looked at this in, in with using cynozine. So it might be a, a useful alternative, for pregnant cattle if you do need to sedate them.

And then we move on to alpha 2s in general, and they're pretty much contraindicated in small ruminants. So, in my early days when I did . I, I was anaesthetizing small room and we did have protocols that, included alpha 2 agonists for both sheep and goats, and, we ran into occasional problems even with very low doses, but certainly in client owned animals, I do my very, very best not to use alpha 2s in in sheep.

Goats. We know, it's well documented that it seems to, for whatever reason, predispose them to seriously high pulmonary hypertension, which results in pulmonary edoema, and at best you end up with a respiratory compromised animal, and at worst, you end up with an animal that arrests. And then when we're thinking about camelids and reindeer, certainly for xylazine, the dose that we would use is halfway, somewhere halfway between horses and cattle.

If we're using domidine, you're gonna use a like for like dose that you would, . That you would use in horses and, and cattle depending on what you do. So, I would normally start it, with domidine at 10 mcg per kilogramme in both those species if we were using it, I might go from 0.2 to 0.25.

And then we move on to butterphenol. Now we've butterphennol has got, it's not licenced for use in, in, food producing animals. We've got no meat and milk withdrawal periods therefore, for it.

And it is a good sedative. It seems to, work synergistically when we. Combine it with alpha 2 agonists, but remember that it's a poor analgesic.

So some people make that decision to use this drug alongside the alpha 2s and think that they're giving an opioid, analgesic, and that is absolutely not the case. And you can use it alone, and there have been studies, looking at its use in North America, primarily where, FDA regulations for drug use in food producing animals are slightly different to what we have here. And it certainly will sedate sick, cattle, sheep and goats, but you don't get a particularly predictable, and you don't get a very deep.

Deep sedation. And I think with a lot of our patients, if we've made that decision that we need to sedate them, even if they're sick, we've usually done that for, for a reason. And probably butolphenol is not gonna, is not gonna cut the, cut the grades.

And then we've got attapamazole, and it always surprises me that we licence drugs, alpha 2s, but then we don't licence, they're reversal agents, which sometimes we might need to do. So, atipamazole, has a, has a licence in small animals. Many of you will have used it in that.

It's not licenced in, in horses either. . It can be used to reverse those untoward effects that we get.

So help to correct recumbency, which we might want to do if we've got a partic particularly if we've got a particularly heavy bovine that's become recumbent and doesn't seem to be, to be getting up when we would expect it to. It can help restore GI motility, and it might well reverse any of the other unwanted side effects that you've, that you've. Go the downside to So in from that Alpha 2 administration.

And you do need pretty big, you do need pretty big volumes, in, in these animals. So trying to, you can't use the same principles that you use for, small animals where you give exactly the same. 90 mLs.

So if you've given a, a 600 kilogramme Holstein 0.6 mLs of ditomidine, 0.6 mLs of of antecedent is not going to do any good at all.

So they're much, much bigger doses. And you certainly can see restation if you give them IV and what we often recommend if you do get yourself in a position where you need to reverse your alpha 2 is to give half the amount IV and half the amount IM. And then we move on to Aceromazine, and Aceromazine is is an interesting drug and there is definitely a Europe North American split regarding its use.

There were a lot of studies that got done in the 60s and 70s that showed acetylprimazine administration significantly increased the risk of regurgitation, and I think part of the reason. For that, is that we often see regurgitation with sedation and general anaesthesia when we've got animals that are lightly sedated and when we've got animals that are heavily sedated and any of you that have used aromazine know you often end up in that sort of angiolytic and mildly sedated stage. However, there has been in, in North America, this is a drug that is recommended for use in small ruminants, particularly use in small ruminants that have got urethral obstructions, and it's certainly made it into one or two mainstream textbooks.

But there is just that risk of regurgitation, particularly. In recumbent animals. And again, in, in Europe, it's not licenced, and again, we've got no, meat and milk withdrawal periods.

And remember that it's half life is pretty long. So if you administer Aceromazine, it's likely to work for somewhere between 2 and 8 hours, depending on your route of administration. And then we move on to chloral hydrate, and I should have put a poll question in here to find out how many people are still using chloral hydrate.

And certainly was something when I was a, a student and a young vet that was still . Routinely, routinely used in, in food animals, potentially not in the way that it was designed. So chloral hydrate is an inexpensive sedative that will depress the cerebral cortex.

It can be given, and often is given initially orally via stomach tube, and then can be administered IV, either after oral administration or after the animal has been. Has been cast. The challenge with it is it has a very narrow therapeutic window.

And if you give something orally into the room and as we all know, there's absolutely no way we're gonna be able to, to get that drug back. It doesn't provide any form of analgesia, and I certainly think when I was a student and I saw it used, it was given probably at pretty high doses and was being used to try and mimic an anaesthetic agent for adult cattle, which it definitely isn't. Now, it certainly can be used as a sedative, but it needs to be used with a great deal of care.

It can take up to 5 minutes after IV administration, and if you don't cast animals and you've given it IV, they certainly can become a very, very attaxic. It leads to severe respiratory and cardiovascular depression, and they are very calm after that sort of initial phase, but the recovery period can take a very long time, both when you use the drug orally and IV. Again, not a drug that's licenced, and again, we don't have any, meat and milk withdrawal periods in Europe for it.

And it, it might be quite fun to find out how many people are still using or are seeing chloral hydrate used. So I now thought, I've sort of talked about the drugs that we've got, not that many. I didn't touch upon diazepam and midazolam.

Probably, although, they aren't licenced for food producing animals in my hands, they are the only suitable sedative slash angiolytic ape. For use in small ruminants. They cause minimal cardiorespiratory depression, used at a dose of around 0.1 milligramme per kilogramme.

There's a a very wide and very safe dose range. Sheep and goats will become recumbent into sternal recumbency for around about 25 to 30 minutes. You can do what you need to do, remembering that it has no analgesic activity, and then those animals normally get back up and will go and join their friends.

Now, as with many drugs that we've got, we again have no MRLs but we don't really have anything else either for, for small ruminants at the, at the present time. So I thought now what I would go on and talk about some of the challenges and some of the things people call me about and the frustration. That they have regarding sedation and we can think about and some of you might have some general anaesthesia examples, but probably people ring me more often about challenges of sedation.

And the first one is thinking about sedation of. Neonates and that might be to do minor surgeries, might be to put casts on or some of the other things that you you might want to do, and neonates are defined in our population of anything under 4 to 6 weeks of age. And the problem with neonates at that age is that they rely upon their heart rate to maintain cardiac output.

So they don't do very well if we give them alpha to agonists, because obviously all the alpha 2. Cause bradycardia, and so if you're healthy, that healthy neonate will probably be OK when you drop its cardiac output, but it's not gonna cope very well if it's sick already for whatever reason that might be. The other thing is that the alpha 2s can cause vasodilatation, much more, much more of an issue, obviously, in, in small neonates because they can become, hypothermic.

And, again, especially relevant if we're doing things with those neonates and they're wet for whatever reason that might be. And neonates aren't small adults. Their livers are not fully, functional.

They've probably got 2/3 of the adult function at birth, and the renal system is somewhat similar. And so they're metabolise and excrete these drugs pretty slowly. So they'll stay sedated for longer.

They're small. So they get colder, and they also have to put up with having that reduction in cardiac output for longer. So, if at all possible, best to avoid, alpha 2s and also ACE promazine, similar impacts are gonna, similar things that I've just said are also relevant to ACE promazine as well.

And so for me, again, for the neonates, the young car. The small ruminants, if you need to, if you need sedation, then diazepam or midazolam are your best bet. And midazolam has now got a veterinary licence.

It's licenced for use in horses, although it doesn't yet have, MRLs for food producing horses, which we might be able to, tag onto the back of. I've sort of said most of this, not for use in Adult animals, because it is a central muscle relaxant. So if you've got an ENA, a young calf, a sheep or a goat, usually, when that central muscle relaxant, effect kicks in, they lie down.

The problem with, adult cattle is that they often become, they panic and they, can become very disoriented and you increase your risk and ataxic and you increase your risk of, Of limb fractures. I sort of said most of this, but certainly that would be my drug of choice if I could choose anything I wanted, that's what I would, that's what I would choose. I would say this is a call I get pretty commonly, people being very, very frustrated about ineffective sedation when the drugs have been administered IM and we'll come to unsuccessful sedation, sorry, IV and we'll come to unsuccessful sedation IM in a moment.

And. And what people often find is they've given a dose of sedation, IV, and it's not really worked. And then they've tried to top it up, and that hasn't worked either.

And I suppose, common things being common, either the drug hasn't gone intravascular, which, if we're using IV in some of these, certainly some of these big beef breeds, isn't an Unreasonable thing to expect. And the other thing to remember is, they are working on the sympathetic nervous system. So if you've already got an extremely excited and wired animal before you give the first dose, the drug is just gonna be unsuccessful, competing with those endogenous adrenaline, with endogenous adrenaline and noradrenaline.

The other thing about top-ups is people are always a little bit worried about giving extra drugs cos they think they've given an appropriate amount IV to start with and then they give really, really small amounts, and a, a really good tip is. If you've worked out your IV dose, don't use a top-up dose that's anything less than half of what you calculated to give, to give IV. The other thing to remember is Xylazine takes 2 or 3 minutes.

Probably IV in a healthy animal to have its maximal effect, but domidine takes a bit longer, so I often timedomidine and I don't even expect it to do anything before 5 minutes. So try and. Make sure you know when you give the drug and be as patient as you can in that, in that scenario because often you've.

Given them the sedation to try and speed up whatever it is you're doing, I fully I realise. And then we move on to unsuccessful sedation with IM administration, and I think the most common reason for this is giving drug intra fat. So.

I think that's not unusual in in some of the, the bulls that we might be sedating IM and I definitely think it's a very common reason why drugs don't work in in pigs. So whenever you're thinking about what about giving IM drugs in, in. Pigs, I almost always use, use, spinal needles to give IM drugs, which I realise sounds utterly horrendous.

But 1.5 inch drugs are largely just not gonna cut the mustard, particularly if you're dealing with, Cooney coonies. And again, drugs are not gonna work if the animal's excited or stimulated, I am or IV.

And then we've got the sedation of the very fractious animal that you can't inject slash has got poor or non-existent handling facilities. Hopefully that's becoming less and less common now. But you certainly can squirt your alpha 2 at mucous membranes.

So, 5 times the IV dose. If you have access to 10% Xylazine, don't give that inadvertently IV either, that doesn't go well. But if you have got 10% xylazine or you've got teomidine where you've got a relatively small volume, if you can get the drug on the, on the mucous membrane, it will often provide you with at least mild sedation so that you can then give a drug another way.

On there we could use ditomidine gel. The active component has obviously got is licenced in food animals and has got MRLs, and that ditomidine gel just makes it a lot easier to get onto the, onto the gums. And then you can dart if you've got a dart available.

My only comment with the dart is you do need to make sure that the dart is long enough, you're not going to be putting that drug in fat, depending on what your. Darting and it's trying to keep those animals as calm as possible in a very safe environment before you before you dart them. We've then got the sedation problems which are always very, very annoying, the cow that goes down, that you really wanted to stay standing and they never seem to go down at a good time.

They always go down when you least. Want them to, and you know, reasons might be you perhaps gave more than you needed, maybe you underestimated how sick the animal, maybe you overestimated the animal's weight, or alternatively, you were just dealing with a cow. And that's just what they do.

So, I think whatever sedative you use, you know, it's trying to pick a sedative and stick to it, so you sort of get a handle on, on what you do. Now, you could, if it was available to you, partly reverse your alpha 2. With attapamazole, it's always worth giving some and then giving a little bit more rather than giving too much because, attapamazole is a stimulant, and if you, over reverse them, they can become very, very excitable.

And if you did need to sedate a sick cow, I suppose my approach would always be, think about what you'd give to a healthy animal, and then give it a third or half of that, of that dose, because most of us haven't got attapa in our car, and, therefore, it's easier to top it up, but harder. To take away. And the other thing is to give some of that drug IM rather than IV will probably have less cardiovascular effects, but it also will take a longer to work, and B, won't be as predictable in a hypothalemic animal because absorption from the muscle is gonna be less consistent.

And we've talked about this already, if you needed a sedation protocol, either for the calf that you're hopefully delivering that's live or for the pregnant cow, then low dose domidine's probably better than than xylazine. It seems to have less impact on myometrial contractility, particularly if you give the drug IM rather than IV. So that's what I've got to say really about sedatives.

So now I thought I would move on to talk about general anaesthesia, and some of this I'm just not gonna have time to talk about today. Local blocks and analgesia is a talk all by itself. So I'm gonna concentrate on prep.

We've sort of talked about pre-medication. Because pre-medication is largely gonna be sedation, depending on what drug we choose for induction. Then we're gonna talk a bit about maintenance and monitoring and where ruminants and Camelis, but where ruminants and Camelids are a bit different in the post-op care that we have.

And I spent some time during my residency at, at And the University of Cornell, which at the time had a, had a very large caseload of ruminants that underwent general anaesthesia. But it's not something we perhaps do as commonly, as we, perhaps should, or that we can for various, for various reasons. So the first thing to note is general anaesthesia is not particularly complicated.

It's just about knowing what those differences are, compared to small animals and horses, and every one of us, even if we've been in farm animal practise since the day we qualified, definitely will have had, enough time. Yeah anaesthetizing small small animal anaesthesia as well. Some of the things to note are that the drug dosages are different because ruminants do some crazy things with metabolism of drugs.

And also, ruminants are often much sicker than they appear. And we need to take that into account, both with the drugs that we use, but also when we're thinking about their needs in terms of fluid therapy and analgesia. And For me, I love anaesthetizing ruminants, but the main part, if any bit is gonna make me tachycardic.

It's whether or not I'm going to be able to intubate them. And if you're dealing with If you're dealing with small room or that you've got a laryngoscope with a really long blade, and they are available to buy commercially, and they make life so much easier. And if you're, trying to intubate adult cattle, you need really thin, long, thick skinned arms because their teeth invariably skin your arm as you're trying to palpate the larynx and feed that tubing.

So I came up with a list of the reasons why I've done general anaesthesia in, in, in cattle, hernia repairs in calves, I know many of you will do those under sedation and local block, fracture reductions in cast placements or maybe fancier things if, You've got a particularly valuable animal. Occasional abdominal surgeries, complex castrations if you can really, if you really want to go down that line. Management of urlithiasis, which is obviously going to be a big thing in our, in our, goat population.

And then in adult cattle, footwork in balls, penile exams and surgeries, and then occasionally, abdominal surgery. I spent some time at UC Davis, when I was, again, when I was a resident, and one of the main reasons that they were anaesthetizing. Adult cattle were cannon bone fracture repairs in the rodeo balls, who were worth far, far more than any of the horses that came into the hospital.

So they were often stabilised and anaesthetized, and they went off and got plates and returned to, returned to their jobs normally. So back at the ranch, it's thinking about preparation for general anaesthesia, and I put this picture in cos it's got so many things that are wrong with it. Any of you that are RVC graduates might recognise that infamous door going into Obs and into the farm Animal Hospital.

And the first thing you need to do is have a really good area to induce anaesthesia and perform surgery. And if you are anaesthetizing large animals, particularly large bulls, having a suitable surface for them to lie on. So, I'm gonna talk you through this picture.

This was actually one of the teaching bulls at the RVC who was a very nice creature until he needed any form of footwork done, and then he's turned into the demon from hell. And you can see here that he's lying on, he is lying on a mat and not on a concrete floor, which I suppose is a start. But this is not an appropriate, floor surface to have a 1000 kilogramme animal.

He's then got a pad between his legs, so it's putting all the weight from this upper leg down through the bottom leg which is gonna predispose him to getting a myopathy and that right for limb. And he's right in front of a door, and I can't show you a picture of the rest of this room, but the rest of this room has got lots and lots of things that he can injure himself on when he gets up, particularly if he's ataic. So we've got the crush sitting out here near Roy's back legs are, and then we've got.

Set of a set of stalls and some other random objects lying around. So all in all, he was not meant to fall over here, I might add, but this was, not ideal. And people were coming forwards and backwards in through this door, having to climb over the ball in order to continue their daily work.

So, things didn't go well this day. This was not an appropriate surface, this is not appropriate positioning, and it's always worth having a plan B. Now plan B's with 1000 kilogramme animals because they're so difficult to move, can be very, very difficult.

So, one of the things that will make life a lot easier is starving prior to anaesthesia, and this is especially relevant in in adult cattle, but also relevant in, in, in adult, in adult ruminants and camelids as well. It will reduce your room and size, which will help to increase that thoracic volume that we always talk about as being pretty small, and in theory, should reduce the risk of bloat and regurgitation, both bloat pre and postoperatively and regurgitation perioperatively. And that smaller rumen should improve ventilation, as there should be less pressure on the diaphragm.

So we'd normally starve in for an elective surgery, an adult ruminant for 24 hours, and ruminants over 4 weeks, starve for 2 to 6 weeks. And younger ruminants just withhold food for just withhold milk for about about 60 minutes. In an ideal world, you would have a cannula placed prior to induction of anaesthesia, especially if you're doing stuff by yourself, it just makes it easier for someone else, be that you or the farmer to top up if you need to.

And jugulars are certainly the easiest and most accessible in cars. Many of us know they're fairly variable in, in adult cattle, and if you're gonna put them in adult cattle, doing a cut down, means that you're not gonna trash the, the ends of your, of your cannula and, and then end up doing damage to the inside of the vein. And I like jugulars in, in camelids as well.

And cephalic veins can also be used, certainly a good choice again in small ruminants and and camelids. I don't find cattle take cephalic vein cannulation very well personally. And you can use, you can put pretty, pretty big, cannulas into both the cephalic vein, and obviously the jugulars, whatever you need.

The sofinas is variably easy to find, and. It's fine if they're anaesthetized, but it's not an ideal vein to be cannulating if the animal is still standing cos it usually isn't gonna go well. And ear veins are fine for very small volumes of drug, but they, they will usually blow if you try to put any larger volumes into them.

And I would definitely, discourage you from using butterfly and cannulas in ear veins, because they go in and they look like they're gonna work. And then they blow that vein, just about as soon as you need them normally. And as we know, we should use local blocks wherever possible, even if we have decided that we're gonna perform general anaesthesia.

It will make the biggest difference to that animal's comfort and welfare if you have, if you've placed that block before you do whatever it is that you're, that you're doing. We've already talked about, xylazine and ditomidine. We're probably going to premedicate with one or the other, as our induction agent is probably gonna be ketamine.

And I've already said to you, aceromazine is certainly not a drug in my armoury for for use in ruminants. Where analgesia's concerned, I think it's really, really important it gets given prior to surgery. There's lots and lots of data showing that makes the biggest difference to, welfare and comfort, to, reoccurrence of feeding, and growth rates, etc.

So we want to try and get whatever analgesics we're going to use, get them in prior to surgery. And then we move on to induction, and probably most widely used induction agents for all of the ruminants and camelids is going to be ketamine. And although we don't have meat and milk withdrawal periods, the EMEA has stated, That because it's metabolised so quickly, which is going to be its downside for all of us, and withdrawal periods are not actually required, and they fully acknowledge we're unlikely to go round an entire herd of animals administering ketamine to all of them, which would be a very expensive day out.

The one thing to note with ketamine is that we need to use much bigger doses than you might be used to using in horses, and some of you maybe in small animals as well. So we're gonna start using. At doses around 5 milligrammes per kilogramme, we always need to have pre-medicated prior to using ketamine and with an alpha 2 agonist.

And then you need to make sure you've got multiple top-ups ready. So if you gave a dose of ketamine to another animal that isn't a ruminant, you would expect to get 20 to 25 minutes of anaesthesia and then they become pretty awake. You're lucky with healthy ruminants and camelids if you get 10 minutes.

Sometimes you might in a sick animal, get 15 to 20, but they metabolise ketamine at a rate of knots, so you need to have lots available to top up, which is why it's helpful to have a cannula somewhere. I'm then gonna move on to talk about alfaxolone and alfaxolone's licence for dogs, cats, and rabbits. And at one point there was some talk that they were gonna try and get this drug licenced for, sheep and.

Goats my, I don't know what happened with that very exciting idea. But I suspect that the cost benefits of doing that, were, were simply, made it, made it not a non-financially viable prospect. But alfaxolone's a neuroactive steroidal compound.

It's got no analgesic properties, which ketamine does have, but one of its advantages is it can be used in unsedated animals. So is a drug that in theory, could get used in sheep and goats on their own without the requirement for some form of pre-medicine, be that midazolam or diazepam or an alpha 2 agonist. It causes minimal cardiac depression, although it certainly in dogs, it causes pretty marked respiratory depression when you initially give it, and it's been marketed for use in critically ill and small animal patients.

It's too expensive to use in adult cattle, but might be a drug to think about in terms of, using calves. I've certainly spoke to some, some farm vets who've used it in small ruminants, and I've used it in small ruminants as well, and in sick camelids. What I would say is, although it can be used in on today.

Animals, they don't have the, they don't, none of them necessarily have the very best recoveries with this drug, and those recoveries are much, much worse without premedication. So in sick animals, if I've chosen to use alfaxolone in a, in a sick ruminant, I would usually have, pre-medicated it with some form of benzodiazepine. And the dose that we recommend for using ruminants is very similar to what you would use in dogs and cats.

Anecdotally it's not metabolised as quickly as ketamine, so you probably don't need to top it up quite as regularly. And then I've got some other induction. I could see some of you were, not based in the United Kingdom.

Thiopentone, has, has in the past had MRLs available for it in food producing animals. It caused is a lot of cardiovascular depression, it's more difficult to get hold of now, and there certainly isn't a licenced product. But it's something I know some of you will have used in the past that might still be using.

And then we've got propofol, not licenced in food producing animals, again, can be administered IV as in small animals, it induces, apnea at at at initial administration, and it's, it's eliminated pretty swiftly. Now I know some people really like using propofol in goats, and I've never quite understood why you would want to use propofol in goats because . It's, it makes it, they are very, very almost impossible to intubate with propofol because it's been eliminated before you've got your endotracheal tube in, and it's gone so quickly that either you have to keep topping it up or start doing con continue.

Rate infusions with it, because often you're gonna really struggle to have got them onto some isofluoran with a tube in. And so for me, I think it's quite, expensive if we're doing things that are bigger than perhaps goat kids or, or lambs. And there's, I don't see any real need for its use while ketamine's available.

Again, doesn't have any analgesic effects. And then when we move on to intubation, so I've got written here calves, but calves could be camelid or small ruminant. They need to be kept in sternal recumbency until they're intubated.

And the key to successful ruminant intubation is not the person with the tube, it's the person who's holding the head. And the holder should ideally straddle the animal and hold its neck up really straight and vertical, and I'll show you a picture of that in a moment. Pieces of bandage can be used to stabilise and open the jaw, and then you really do need a long laryngoscope blade to try and visualise the larynx.

On whatever size tube you think you need, you probably are gonna get one in that's several sizes smaller. One thing that I found really, really helpful is stiffening of the tube with either a plastic covered stilette, which I do have now, which is the sort of fancy version of the old thing that I used to have, which was the straightened part of a metal coat hanging. Don't seem to get those very often anymore, although I don't go to the, dry cleaners very often.

And then you, you tie your tube in around your upper jaw, just as you, you know, just as you would have done with a, with a small animal. You can intubate them through the nostril, but it's much, much more difficult to do, and you need very small lubricated tubes. And it's a hard thing to do without causing, nosebleeds.

So here, here we've got, calf being intubated, really long laryngoscope blade, but this neck is absolutely vertical, and same goes for this camelid. You can see the heads held up, and we've got that head and neck just need to be really straight. And it doesn't matter that you've still got a curve down here cause you're aiming obviously for that proximal third of the neck to to put that tube in.

And then I have several pictures of intubating adult cattle, and whenever you look at them, actually, it doesn't make any sense to anyone else looking at them. It just looks like there's a cow lying on the floor, and there's a random person lying on the floor next to it. So, normally you'll have the cow in lateral recumbency, and if I get a choice, I quite like them to be in left lateral recumbency because I'm right handed.

So I can then feed my right hand in lying on my right hand side and push the tube down with my left hand. Really important to get a drink water gag in and have that, secured, and sometimes that could be a person's job if you've got the opportunity to have a spare person. And then you put your arm into the mouth, you palpate the larynx, and then you feed the tube under your arm and through the larynx, and it makes it sound really easy, and it's actually really not that easy because there's not very much space.

If you, can't get it at the tube in, and again, you often need tubes much smaller than you think you will, I can remember doing an, an Angus ball, and we, got a 20 millimetre tube in an Angus bull in. You know, you look at the body weight that he'd got, you'd think you would get a 24 or a 26 millimetre tubing, but actually that larynx is really pretty narrow. But if you can't get the tube in that you've chosen, then the easiest thing to have help you is to have a really small stomach tube that you feed into the larynx.

And then you put the endotracheal tube over the top. The one thing that's really important is you make sure that those two tubes actually fit and work together prior to, prior to attempting this. And then one of the things that always comes up is, should we orogastrically intubate them, and I know that some people do practise this, but the thoughts are that.

And the reasons for doing it are to try and prevent The development of gas bloat perioperatively. But what seems to happen is you stimulate and dilate the cardia, and that encourages regurgitation and promotes contamination. And it doesn't appear that you ever get your tube into the place that would be useful for you to help, help relieve, a gas bloat when you, when you want to, when these animals are, are in, lateral recumbency.

I'm sorry, this slide's very busy. And then we think about maintenance. So for lots of us, if we're doing anaesthesia on farm, .

Mhm are a lot easier. I've got that bull lying in front of the door. I don't have another picture of him.

I'll go back one. OK. Mom, I've set it here for use in farm animals, and it's got a 20 litre bag, and we'll talk about bag sizes in a minute.

It's got a large animal circle and it's got a canister for some soda lime. And that picks up, doesn't actually, even though that was a pretty old example, and it doesn't actually weigh that much, and it would sort of fit onto in the backseat of your car. So we did used to take that out occasionally onto, .

On the farms it then with Probably gonna use isofluorra, and a little bit like what I told you about ketamine, although isofluorra does not have MRLs and it's not licenced for use in food animals, the European medicine directorate or EMEA has stated that as long as the animals. Not Yeah. Immediately after.

When you're using, for most of the animals we're gonna deal with that are gonna be above 10 to 15 kg, we're gonna want to have them on a circle circuit, and therefore, we'll need a re-breathing bag, 2 litres for calves and small ruminants in. Halids, and then bigger if we, if we're doing adult cattle and 5 to 10 litres is a minimum. And if you can get hold of equine bags, which are often 20 to 30 litres, then they will be fine and prevent rebreathing.

I've already talked about top-ups. And then in terms of monitoring and the things that they do, there's not really any differences. We can monitor as much or as little as we would in other species.

If you induce anaesthesia with. Tentone, propofol to alfaxolone, ruminant eyes will rotate cranio ventrally, and they'll do that if you also administer isoflurane. If you use ketamine and you don't then follow that up with inhalational isofluorra, the eyes will stay fixed and central.

And remember that we want there to be a weak palpebral reflex, cos we want these animals to be still, but we do want them to be alive. And we can use all the same monitoring that we might want. And it, it is helpful to, to have some form of monitoring, particularly if you're dealing with young or sick animals.

And this was, actually one of the, my research cows at the RVC. She had got a mass that was, underneath her abdominal aorta. And we tried.

Left and right flank to excise this mass and had failed. So here she is, lining lateral, left lateral recumbency. And I just wanted to show you, you can do the same sort of stuff that you would do elsewhere.

She's got a base apex, a modified base apex ECG on, she's got an arterial catheter in her aricular artery. She's got indirect blood pressure causes this took a little while to get in. She's got indirect blood pressure on the proximal falling.

We did some work placing adult cattle to get an indirect blood pressure readings. There's a catnograph attached to the tube, I think that's pretty, pretty much where we've got with her. But what's most interesting, and I did sort of allude to this when I was talking about use of alpha 2s, is hopefully on this bottom part of the, multiparameter monitor, you can see, this is the Capnograph trace.

So the entidal CO2 is pretty normal. So we expect it to be around 40. When any of you that do equine anaesthesia as well, we only Dream to have entitled CO2s during surgery of 14.

But what you hopefully can see is the very fast respiratory rate that we've got in this cow. So, having respiratory rates anywhere between 30 and 50 beats per minute. Now, those of you that do small animal might think that this cow was at a light plane of anaesthesia, but actually her end tidal lysoflurane.

Was was pretty appropriate, but this is a very, very common pattern that we see in ruminants and camelids that have received alpha 2s, because of the fact we're having such an impact on their respiratory systems. So then what about some ruminant specific issues? Saliva is the big one.

And this is not such a problem in pre-ruminants in calves and in goat kids, but the. That you start anaesthetizing adults, there is excessive amounts of saliva, and it seems to form like an ice rink, underneath their nose. The other thing to make sure is that you keep it away from their eyes because the pro.

TACs, if you're unlucky, can end up causing corneal ulceration. And then we've got regurgitation, and the only tip I've got for preventing regurgitation in anaesthetized animals is make sure that they are neither light or deep. They just need to be at a surgical plane of anaesthesia, and it will help reduce the risk of regurgitation.

And I anaesthetized, a goat, a few weeks ago, and the biggest problem with this goat, and why it was regurgitating was because it was too light. But if the animal does regurgitate, it's trying to suck out the contents within the pharynx, and if you've got the animal intubated, making sure that when you extubate it, you leave that cough partially inflated. And if you don't have a fancy.

Suction unit, which I often don't have these days, then some form of piece of tubing and a big syringe and some water so that you can wash out what's often quite sort of thick and mucus, mucousy, is really, really valuable. And the The thing that we probably have to get least excited about is hypothermia, certainly when we're working with, adult, ruminants and camelids, but small calves can certainly develop hypothermia, especially if we get them wet or we're doing abdominal surgery. And you can do all the same things that you, that you would.

Do in, in small animals. We very recently did a crypt orchid surgery in a pig in the field in February, and we just had, I thought he would probably be OK. He was a well-conditioned, Cooney Cooney.

He was an adult Cooney Cooney, but in fact became. Very, very cold very quickly. And the only thing that we could do was use a heat lamp and lots of blankets.

And actually, we got his temperature, back up to something that was peripheral temperature, something that was reasonably normal within 2 or 3 hours, despite the fact that the external temperature was pretty cold. But, routine use of things that keep them warm should probably be discouraged. Think about assessment and monitoring on an individual basis.

This was an embryo transfer calf that had some stuff done to it, and certainly that got very cold and you can see here is on a, on a bear hugger. This was actually a standing surgery, not a general anaesthetic surgery. This was done on a very cold November day.

This is a pyelonephritic kidney that's been removed through a right flank laparotomy, and this is an adult dairy cow. And we managed to drop her temperature to a peripheral temperature down to about 33, and it wasn't a particularly long surgery. But we did manage to steal one of the equine 6'6 rugs that she, actually tolerated remarkably well.

One of the lovely things about ruminant anaesthesia, 9 times out of 10, is that they recover in a really, really calm manner compared to any of you that have seen horses. The one thing that you can't do, however, is rush them. So they will often sit in sternal recumbency for quite a long time, and if at all possible, it's best you don't extubate them until they're swallowing, cos we've got a pretty high risk of regurgitation at this stage.

And trying to. Prop them off with their head up and can be really helpful. So here is the sorts of positions in an ideal world we're gonna want those adult cattle to recover, but don't expect that they're going to get up anytime soon.

We try and reintroduce food, start with hay or or . Not too good quality silage and avoid concentrates for sort of 12 to 24 hours, and monitor for signs of bloat. And certainly if you end up getting into the need to sedate or anaesthetize, you know, individual animals such as bulls, if they bloat once, they're probably gonna bloat again.

And then making sure that you keep that analgesia going for as long as you, as you need. And on that note, I will thank you all for your attention, and I will try and answer any of your questions and and comments. Thanks very much.

Brilliant. Thank you so much, Gayle. That was an absolutely fantastic webinar, full of practical tips for everybody listening.

It has generated an awful lot of questions. So we will not, we will not be able to get through them all live. I think we've probably only got time for, for one or two.

However, if you have questions, please still put them in the Q&A box, because we will ask Gayle to answer all of your questions after tonight, and we will see. And we will circulate it around everybody who's been listening. So please just pop them in the Q&A box.

Also, before you go tonight, and we have loads of you online tonight, it's absolutely great. Could I just ask all of you that are listening, just to spare 30 seconds to complete the feedback survey before you sign off? It should have popped up in a new tab browser.

We We do read all the feedback. We do listen. Tonight's webinar is actually a request, so we do listen, and we do, take requests.

So please help us plan our programme for next year. If you can't see the survey or you're listening to a recording of this webinar, then please feel free to email any feedback you've got to the office. So office at cattlevet.co.uk.

So as I said, we've got loads of questions, we've got nearly 20 questions already for you, Gail. But what I'll do is I'll, pick out just one or two of the, the practical ones. We've had quite a lot of questions about licencing and off-label use and things, but I'll, I'll stick with the practical questions for now and we'll answer the other ones, offline.

So just a question here about, best practise, sedation for disbudding. So this member has asked that they're currently using for disbudding 1 mL of xylazine IM at 4 weeks of age, finding it works really well, making sure in deep bedding for warmth, sleep for 20 to 30 minutes. Any comments?

I mean, I think it's fine as long as they're healthy. That's all I'm gonna say. So I think, I think that's, I think that's absolutely fine.

I think that as long as that is combined still with a local block and that it's not replaced, the sedative is not replacing the local block as well, then I think it's good practise. I think if you're using it instead of a local block. Maybe not quite so great.

Brilliant. And obviously non-steroidal as well, in line with sorry, yeah, obviously, but certainly, certainly a local block as well cos I think certainly in other areas of veterinary medicine, not farm animal practise, that's where people cut back, right, they don't do their local blocks, they still give their non-steroidals or their opioids, but they don't do their, their local blocks once they sedate or anaesthetize animals, which is a big mistake. Fantastic, brilliant.

OK, so we have another great question that's come in here. Do you have a preferred induction agent for an animal with suspected raised intracranial pressure? Good question.

So, 20 years ago, the answer to that would have been, we definitely wouldn't have used Xylazine, but the latest research that there is in just about every other species, including experimental sheep and goats, is that the risk of xylazine, sorry, the risk of. Ketamine causing increases in intracranial and intraocular pressure are actually nonsense. And now, for human patients that have got traumatic brain injury, ketamine is their first line, both analgesic and induction agent.

So the answer to that for me would be ketamine all the way. OK, brilliant, thank you. And a question here about recommendations for sedating cows undergoing caesareans.

So, the person posing this question has had to do it twice as a last resort with a very fractious animal. They only had xylazine available, which they gave IM, but was very nervous doing it because, obviously you've got a wound up animal. In both cases, the calves were alive but quite dopey.

So what advice would you have in that situation? Well, I think this is where Ati Pam can come in. I mean, my experience of sedating things for Caesars, I'm sure there's other people online is.

Why do they always lie down just when you don't want them to, right? So if it stayed on its feet, that's really good. But the, the, the answer is, if you, if you do have access to atoppamazole, that will help you can give that IM to the calves and it will help reverse, the alpha 2.

But otherwise, if you don't have that or you don't want to use it, then it's all about supportive care, trying to dry them and get them warm, and they, you sort of treat them like a high risk animal and that they probably need closer monitoring than, a standard caesarean calf from a caesarean. OK, great. And I think we'll, we, we still have questions coming in.

Please keep them coming in if, if any crop up. But we'll probably make this our last question to answer live. Really great question again.

So you mentioned about splashing alpha 2's on the. Because membranes, have you got any tips for, for doing this in a practical situation? For example, would the vulva work from afar, I'm thinking of outstanding person standing right back from the cow and squirting it through a super.

Something. But what, what tips have you got? Yeah, I suppose the times that I've used them have usually been people that don't have crushes and have got obnoxious male animals, not always bulls, but obnoxious male animals and.

Sometimes if they will, if they will flame in, then you get your chance to, which they often, they will if they're angry enough, you get your chance to put them on, but the, the other thing that I have used, . In more recent times, when I've had it available in the car, which sometimes I have, is to use the ditomidine gel that's made for horses, and although that isn't licenced in food animals, the active preparation is. So we have MRLs for deerines.

But I think domidine or small volumes of, I think domidine is your best bet because you can use small volumes and you can also repeat it. Fantastic, thank you. So I think we'll call it a day there with the live questions.

We still have got over 20 unanswered questions for you, Gayle, but as I said, we will make sure we will make. Sure that we get those answered for everybody. But I just want to say thanks again for taking the time to talk to us tonight about anaesthesia of farm animals.

We've got some great comments coming in, awesome webinar, really informative. It's gone down really, really well. So thank you very much.

Some of you have been asking whether this will be available as a recording. Yes, it definitely It will be, within the next couple of days, it'll be on both the webinar vet and the BCVA, members section of the website as well. Just a reminder of the remainder, of the webinars we've got this, this year, we've actually got an extra one in just two weeks' time, which is on the real cost of bovine respiratory disease, engaging farmers in.

Change. That's a joint webinar we're doing with AHDB Dairy, and the guest speaker on that one will be, Mike Overton from, from the States. Invitations to register will be sent out by both BCVA and AHDB in the coming weeks.

So please keep an eye out for that and make sure you register. So, we hope that you enjoy, you join us then. But in the meantime, I just want to say thanks again, Gail, absolutely brilliant, webinar tonight.

And to everybody listening, thank you for joining us once again. Good night and stay safe. Thank you.

Bye.