Good evening everybody and welcome to a platinum members evening webinar. My name is Bruce Stevenson and I have the honour and privilege of chairing tonight's webinar. We have a great, great session for you tonight.
Very exciting speaker on a topic that is very close to my heart. But before we get onto that, we have some new members that have joined us tonight. So welcome to those.
I'm sure you're going to enjoy the webinar like the rest of us do. Just a little bit of housekeeping. If you want to ask a question of our speaker, all you need to do is hover your cursor over the screen.
Your little black control bar comes up. There's a Q&A box. Click on it, type in your question, it'll come through to me and we will hold all those questions over until the end.
Likewise, there are going to be some poll questions through the talk, and we will explain that as we go. So don't stress about that. Just enjoy, the beauty of the webinar vets.
So tonight's speaker is Doctor Robertson and she received her veterinary training at the University of Glasgow, followed by training in anaesthesia and a PhD at the University of Bristol. She is board certified in anaesthesia as well as animal welfare. The first one from the American and European colleges and in the, and in, trained in small animal acupuncture as well.
Her research interests include assessment of pain and the use of opioids in cats and the development of anaesthetic protocols for large scale spay and neutering clinics. In 2014, Sheila completed her graduate certificate in shelter medicine from the University of Florida. And she has been a faculty member at the Western College of Veterinary Medicine at the University of Florida, Michigan State and served as an assistant director in Animal Welfare division of the American Veterinary Medical Association.
Sheila, welcome to the webinar vet all the way from the US and it's over to you. Well, thank you very much for listening in tonight. So, despite everything that was just said about my, past, I'm now working in a very, different, very specialised area of veterinary medicine.
So I'm the medical director for the Lack of Love Veterinary Hospice. So we do a lot of older geriatric care and in-home euthanasia. And I would just like to mention that I do consult with some drug companies who are listed on this slide, mostly as an educational speaker and advising them on what the needs are, for pain management and for some of our geriatric patients.
But what I'd like to talk to you about tonight is something I'm very passionate about. I've been very passionate about paediatric anaesthesia, and now, focusing on geriatric, an older pet anaesthesia, and realising just how different this group of animals are. So the talking points tonight, I'm going to define who these patients are, predominantly the dogs and cats, and who are they when they come into our clinic.
And then what I'm going to discuss is their needs, which are different from some of the more robust younger animals that we deal with, and discuss the physiology of ageing and specifically why some of these things are going to affect how we actually approach their anaesthesia. And so, one of the things that you probably have encountered yourself, is even thinking about your parents as they age. I mean, should they undergo anaesthesia, which a lot of us have this fear that it's a riskier thing than surgery for some reason.
And now actually have the surgery done. So this actually means that in the human world, a lot of older people don't get a very painful hip replacement because of the concern sometimes of anaesthesia. And so I think it's very good to talk about.
Ageing, but put it in perspective with what people, ourselves and our clients can understand, which is, you know, how we age. So what I've got here on the screen is a span of 50 years of 3 photographs of my father, two of them with my mother in it. So my father on his wedding day, and then my father on the right hand side at age 76, having just undergone some very, very intricate eye surgery.
So this is a span of 50 years, and just by looking at the pictures, you can see what has happened as far as ageing to skin, the amount of muscle, and how robust, he, he looks. And I think when we think about that and translate it to the pets we deal with, it really makes you think about what you're handling. So here's one of my many cats that I have owned, a little Kermit.
So at 3 months of age on the left there, he's pretty fired up, crazy little kitten, and I didn't think twice about anaesthetizing him to do his castration. Just, you know, pop him with some drugs, no blood work, just a physical exam. But when you see Kermit on the right there at age 15, And probably you're all counting up or trying to guess all his comorbidities, and, and what's happened as he's aged.
So here's a very, very different cat who did need anaesthesia for a procedure, and that made me hesitate a little bit, and I had to think a lot harder about how I was going to handle him, do his anaesthesia, his recovery. And so if we look at some proposed age comparison charts, and they're all a little bit different, but if we look at cats and dogs and look at sort of human equivalent in age, I think we can say that cats age in a fairly uniform way because of their size. And although some people would argue exactly when we categorise them as being senior or geriatric, certainly above the age of about 12.
Geriatric, certainly they're definitely ageing. But with dogs, they don't age in a uniform way, so we do need to look at how they age related to their breed and their body size, mostly, and try and predict, you know, when they become, you know, aged based on them reaching about 75% of their expected lifespan. So, what I like to think about is that the dogs age very differently, the cats I can kind of categorise in one large group.
But if we think about it, Hermit, my little cat, at age 15, was very, very similar to my father at age 76, and I knew how, you know, how delicate they both were at that time. So I just like to know from the audience, what percentage of your patients do you think are in this age group of being senior or geriatric? How many do you think you're seeing?
I'll just think back to last week. What do you think? Right, folks, so for those new guys with us, it's very simple.
Just click on the answer that best suits your opinion. And those will all come through to me. And then as soon as the numbers are up and you've all had a chance to vote, we will end that poll and reveal all those answers.
So just click on the answer that best suits what you feel applies to you. Alright, we'll give you another 10 or 15 seconds. We've got a couple of stragglers.
Remember this is anonymous folks, so there's no right or wrong answer. Just click on the answer that best suits what you feel. Right, Sheila, I'm going to end that poll and reveal the answers to you now.
So there you go. OK, so very, very interesting. That is what I expected to see.
So it looks like we've got winners at between 20 and 30% up to some of you are seeing over 50%. So that's really good information for me and then I will go ahead and tell you what the current data is that I've managed to collect. So when we look at the older patients, I have surveyed AVMA statistics, they do a huge amount of research on the sort of demographics of pets in in America, and also a lot of the large corporate practises.
And so at the moment, we think at least 30 to 40% of pets that visit a veterinarian are in this older age range, and this population is growing as we come, become better at disease prevention, preventative care, and so on. So all of us are going to be dealing with a lot more geriatric anaesthesia cases. So one of the things that I certainly hear an awful lot from owners and from vets that consult with me about these older pets, and what is are they too old for anaesthesia?
And a lot of people are told by their veterinarian, that yes, your dog could well do with the. Mental, but because of its age, it probably shouldn't be done. And I, I find that very, very sad, and the same with, cats, for example, this cat Morgan, who is currently 16, why shouldn't we anaesthetize Morgan if he really does need a procedure done.
So, in my book, certainly dental would be the number one reason that a lot of these older pets need to be anaesthetized and should be anaesthetized. And some recent data came out last year showed that about 88% of senior geriatric dogs have dental calculus and almost 50% have gingivitis. And so the other thing that is very interesting to me, this year, a paper just came out showing that periodontal disease and its severity in cats is associated with the development of chronic kidney disease.
So dental care is something that's absolutely vital to long term care of animals, and one of the reasons we anaesthetize the geriatric population. So what is the risk of anaesthesia related just to age? So Dave Brodbelt did a huge study, it's actually back in 2007, this was published, and he actually had over 80,000 cats prospectively monitored in the study.
And he was able to tweak out what was the risk just related to age in cats, not related to their health status or why they were being in theseized, just purely to age. And what he revealed in that study was that cats over the age of 12, but I would definitely consider. A senior geriatric are 2.1 times more likely to have an anaesthetic mishap than cats aged between 1 and 5 years.
And we're going to explore like, what is it that's happened in those older cats that leads to that increase in risk. Now, I wish we had that data for dogs because owners, you know, ask, well, what's the risk when my dog is this age. But in his study, when they looked at dogs, they just did the actual age, so they put them all into over 12, and there was a higher risk.
But as we've talked about before, that's really not appropriate because on this chart you can see that if you're a chihuahua, you know, you don't often die at a young age. And if you look at this chart, there actually are no very long. Larger breeds, represented in the over 15 years.
So as far as I know, no one's done a study looking at appropriately ageing dogs in order to look at their anaesthetic risk. But we're going to assume that as they age, that they are at higher risk, and we should be aware of what those risks are and how to prevent any mishaps. So I think that there are 3 categories of older pets.
This is how I look at them. We've got the old but healthy. But underneath, and you may not even see any of this, there are age-related changes.
Then we have the older animals with subclinical organ dysfunction, which isn't clearly, you know, showing itself to us or the owner, but if we look for it, sometimes we'll find it, and then. We have the older pets that have clearly overt disease and often multiple comorbidities. So cats would be in that group for sure, cause I think a lot of the older cats have more comorbidities than the dogs, like my little cat, Kermit, that you saw at the beginning.
So I'm gonna focus mostly on just the physiology of ageing, and so even in those healthy, what we think are healthy animals, if we look at what happens in people. People age differently. So this is just the physiology of ageing.
So people can age well. They can age averagely or they can age prematurely, and that's what this chart shows. And basically it's all about looking at the difference between sort of basal function and what your functional reserve is, like, you know, what's your maximum heart rate that you can actually get to, and this all drops off for every organ, the functional reserve in the liver, the kidney, the lung, the heart is going to decrease over time.
And that is the same for animals in all the studies that I have reviewed, but again, I feel that animals age, you know, some of them age well and some of them don't age well. So one of the things that worry us, us in anaesthesia about these ageing changes. So there is a decrease in muscle mass, skeletal muscle, and an increase in fat.
So the two main issues regarding that are with less skeletal muscle, they can't produce as much heat, especially postoperatively when they start to shiver, they don't warm up as, as fast. And this change in body composition is going to affect how drugs distribute, and we will spend a bit of time on explaining the pharm pharmacology of that. The brain, most of us who are over the age of 30 know that the size of the brain decreases in, in people, and that's true of animals, and the number of neurotransmitters decreases as well with age.
And that's where all of our anaesthetics work in the brain. So that's going to affect it. So actually with age, the anaesthetic needs decrease, and we have to adjust for that.
And there's also an altered thermostat. So elderly animals have slightly lower body temperatures usually. And their ability to heat up or cool off, is, is in a wider range than young animals, and they tend to seek out heat more than the younger animals.
With the heart, it becomes less elastic and it becomes stiffer, so it's less compliant. The other thing is there's less sympathetic responsiveness, so if there is a sudden loss of blood during a procedure. The heart doesn't kick in with increase in heart rate and blood pressure, the way a young animal may.
The other thing is their cardiac output and circulation decrease and circulation slows down with age. So think about that when we're delivering drugs and drugs are being distributed throughout the body. The lungs obviously really important for everything, including the anaesthesia and the alveolar surface area, so it decreases with age.
So we have less area, surface area for gas exchange, lung volumes are, are altered, and the lungs become stiffer, so that increases the work of breathing, and I'll talk a little bit about how that's even more exacerbated when we turn the dog or the cat who's elderly on their back for a procedure. And the liver and the kidney, there are decrease in tissue mass and a decrease in vascularity and profusion, so clearly going to affect anaesthetic drugs that are metabolised in the liver and are excreted by the kidney. So they also can't tolerate a lot of water and salt loads that so if we give them a lot of fluids, inadvertently, they don't handle that, but they don't handle fluid losses from vomiting and diarrhoea as well as younger animals either.
And one thing I think is overlooked an awful lot is the change in bone marrow and all the good things that come from bone marrow. Those are decreased with age, and so immune competence decreases with age, so older pets are at more risk of infection from their catheter site or from the surgical wound as well. Let's go back to renal mass cause it's really important and function for the excretion of most of the drugs, either directly excreted or after they've been metabolised by the liver.
And the biggest issue for us is Detecting when there is a loss of renal function. So there are some new tests like SDMA which might alert us to the fact that we've lost renal function at about 40% has been lost. So that is an improvement on if we still look at things like creatinine, which won't actually change very dramatically until we've lost about 75% of renal function.
And creatinine can also be the actual data can be confusing to look at that, because the older animals are losing muscle mass and creatinine is also released from muscle. So this is a problem that we may not know we're going into procedure with severe loss of renal mass, because these animals are usually extremely well compensated. Because they have free access to water, but if we challenge them with fluid losses, and that could include removing their water bowl, when they come into the clinic, or if they vomit and have diarrhoea, and the other challenge would be if they become hypertensive during anaesthesia, that is really going to challenge these old kidneys, and hypertension occurs in over 30% of patients under anaesthesia.
So we know very little compared to human anesthesiologists about how we should ad adjust drug doses based on renal function. In humans, what they do is they run creatinine clearance tests, they have charts, they can go and look at how you should alter the dose or the dosing interval for specific drugs. And in the veterinary literature, I can only find data on one drug, and this is an ongoing study that's going to be continued.
And this is looking at how to adjust the dose of gabapentin, which can be used for pain or for keeping cats a little bit more sedate prior to a procedure. And it is renally excreted, and these are suggested recommendations for adjusting the dose or the dosing interval in these cats with renal the old kidneys, basically, those cats with the old kidneys. But we don't have data on very many other drugs at all, and that's something I hope we soon get.
So going back to body composition, most of us, well, and our pets are all made up of water, muscle and fat, with a few other things like bone and a few other things that really don't come into pharmacology or pharmacokinetics, and how those compartments change is really important with anaesthesia in the elderly. So if we look at what we're doing in anaesthesia, basically, when we are doing an induction drug, we're injecting into the central compartment, and it gets taken by the blood, to the vessel rich compartment, and that really is the brain, the heart, the liver. But the reason the animals wake up is that it then is distributed away from the brain and it goes into the the the sink of muscle and fat.
But these compartments change with age, as we've already said, and so what happens is the actual central compartment is smaller than our older pets, and the muscle is a smaller compartment and the fat is a bigger compartment. So what happens is the plasma levels and the brain levels don't decrease as quickly, and there's a chance for the very fat soluble drugs to accumulate and be slowly excreted or removed in these older pets. So that's something to think about.
But what does it really mean? So this is a schematic to try and make you think the next time you're injecting IV into a young animal versus an old animal. So I'm just gonna take an example that we're going to take 2 makes per kilo of propofol and give it to a young dog that weighs.
25 kg and an old dog that weighs 25 kg. So if we go ahead and inject into the young dog, into that larger central compartment, the colour there is the concentration in the central compartment that's gonna go straight to the blood rich, compartment, including the brain. But if we take the same dose and give that to the older animal with that smaller central compartment, What we have is a lot more drug now that's going to arrive at the brain, which we have already said has a decreased requirement for anaesthesia as they're older, and so you can see how we can run into real issues of overdosing these animals.
Talking about muscle loss and why that's important first of all, as a sink for a lot of the anaesthetic drugs, but it's also important for how the animals actually cope in our clinic. So there are two types of muscle, type 1 and type 2, the slow twitch and the fast twitch, marathoners and sprinters. But what happens with age is that we lose type 2 muscle more than we lose type 1.
Now, why is this important in looking after these pets in the clinic? What it means is that because they don't have that fast twitch muscle, we'll show you one of my old dogs. This is Angel.
So have trouble with that fast contraction, the getting up part, getting up, but once they're up, they're pretty good. So if you think about an old person who has difficulty getting up and rising from a chair, but once they're up, they really get moving. That's exactly what's happening in our pets.
So, I'm going to talk about some of the tricks that you can use in the clinic to help overcome this problem of getting up. The other thing I think is absolutely important to mention is cognitive dysfunction in this older population. I call them the old and the restless, but cognitive dysfunction in dogs and cats, we deal with it a lot.
It might be why the owner came to talk to you, because their pet is keeping the whole family awake at night, so they're disoriented, they have altered interactions with family members, disrupted sleep, aimlessly wandering and vocalising. And so we will see this in this pet population and the concern postoperatively is a lot of these behaviours can look like pain. So it can confuse us, are they, you know, cognitively inappropriate, or are they painful, and that can be a real challenge.
The other thing is, these older pets that have cognitive dysfunction often arrive at your clinic. It's a new place, they don't like changing their schedule, and a lot of them I find will give up. They just kind of come in and they give up, and they shut down and don't want to interact.
And that's another issue we need to address. So, those are some of the physi physiological changes that happen with ageing. In, in our, in our dogs and cats.
So what I'm gonna do now is talk about the challenges of anaesthesia and the things we're likely to actually encounter with these older cats and dogs. Now, a lot of these things you're probably are going to say, well, I encountered all of these problems with any patient sometimes during anaesthesia, and that's certainly true, but they're usually exaggerated in the older population. So this is my 4 big Hs of of anaesthesia.
So hypothermia, hypoxemia, hypovolemia, and hypertension. And because of the physiological changes that I've talked about, these will clearly, I hope I've described that well enough, are going to be exaggerated in the older dogs and cats that undergo anaesthesia. The other thing is, when I compare all the human literature and what I've gained over 37 years of doing anaesthesia, is that the issues during recovery are very, very similar between humans and animals.
Delayed recovery, very common in older people and older animals, and not being quite normal mentally, immediately in the recovery and then resuming normal everyday activities, I think is an issue with the older. Wow. So we talk about anaesthesia, and a lot of you will think anaesthesia, OK, you know, what's my pre-med, what's my induction going to be, but I look at it as a complete circle, and that circle and that whole schematic for the pet and for the owner and for us, starts at home and finishes at home.
So we are going to go through this entire circle here, so that we're thinking about the dog and the cat at home, and then going through the process and then returning home, better than you is what our goal would be. So thinking about starting at home, is there something we can do to even make the anaesthetic experience better? So if you have a client and they've you've had a consult and the dog or the cats coming in for a dental, I just chose November 4th, that's a long time in the future, .
But you know when they're coming in, what can we do to make that whole day better? Well, I certainly think for cats, giving them gabapentin, giving the owner gabapentin to administer at home prior to the journey, certainly makes them sedate and calmer, and there's a lot of data to support that. Some dogs are very, very anxious, and if they're not already on behavioural drugs, then trazodone can be very helpful to cope with their, for them to cope with anxiety and make it easier to handle them in the clinic.
The other thing is, I think we underestimate how many dogs and cats actually get car sick, and so if they do, we should, we definitely should ask the owners if they do, and if they do, then they can be given mropotent for that appointment, and they can give that the night before or the morning before travel, and that will help them arrive in a much happier state. Then looking at arrival at the clinic, you might be very, very proud of how shiny and clean your clinic floors are, but this clinic floor and this clinic, picture here is very attractive, but for an older dog, this is something that will make it freeze or hug the wall and perhaps like slip and, and injure itself. So the clinic environment can be Actually very frightening for older pets.
And so things that I've initiated, where I've worked is that when an older dog arrives and it doesn't have a harness, we put a harness on it. So this way we can guide them around the clinic, and we'll show in recovery, we put these harnesses back on, so the nurses can help lift them up, move them a lot more easily. And it takes away the collar around their neck, cause they might have glaucoma, they might have larA.
We don't want them coughing. Other things that I've done is you can buy these sticky socks up on the right-hand corner of the screen there and slip them on their feet, and that stops them slipping on the surface. And the other thing is, if you leave them on, it keeps their feet warm during anaesthesia, and that's one of the Biggest sources of heat loss.
The other thing is you can roll down yoga mats in your clinic, buy nice cheap ones, they can go in the laundry, and dogs will walk much more confidently over these than a slippery floor. The other thing not to forget about is acute and chronic pain. A lot of these pets we're dealing with are geriatric with OA.
So we might be rushing in to do an emergency surgery on the left here, this dog had a hemo abdomen. It also had pretty severe elbow OA and just think about that dog, the way it's positioned, it's not on very soft padding. We've positioned it so the elbows have a lot of stress on them.
That dog's incision might be good tomorrow, but that dog is going to be crippled because of the way we positioned it. And also, a lot of times, we stop the non-steroidals, in this case, because it's a hemoabdomen. And so think about how that might affect the dog.
One of the most uncomfortable places in the clinic is the radiology table. Again, even if they're under anaesthesia, positioning them and so on, be careful cause it really can cause a flare-up in their OA. And again, this little cat here was obstructed, urinary obstruction, had hip arthritis, and that position is not gonna make his hips feel good the next day.
So we need to think about how we position them and do it more gently with better padding and so on. And I use a lot of memory foam and very, very loose ties or no ties at all on them when they're older. So pre-operative assessment, we definitely want to do this well.
So history, always important. A lot of older pets have a lot of drugs on board. Sometimes it's polypharmacy, but sometimes they're very needed drugs, cardiac drugs.
Maybe behavioural drugs. Physical examination is where we're gonna pick up an awful lot of information, just like every pet, and then should we or shouldn't we run blood work and we'll look at some of the data that would support that yes, we should be looking at blood work in the older population. So this is just one of several studies that has been done.
This was done in the UK. The average age of the cats in this study was just over 11, almost 12, and the dogs were 10, so definitely the population we're talking about, and they looked at screening dogs and cats before anaesthesia. And this is what they found.
So based on the history and the physical exam, the blood results were actually only totally unexpected in about 1% of cases, emphasising the skill and the art of veterinary medicine still. But based on the blood work, some cases were postponed, and often that was because they wanted to get the dog or cat onto fluids for several hours before they started. But the actual protocol was changed in about 4% of dogs and 9% of dogs because of something that came up on the blood work.
So I think probably most of you are doing pre-op screening in this population, and certainly this supports that that you may get extra information, and if nothing else, a baseline for then following up. So the other issue we need to deal with is, you know, what's normal blood work for older pets. So this is data that came out last year, and these were 100 dogs that the owner and the veterinarian said were very, very healthy, you know, these are super healthy, acting, you know, like.
Great, well dogs that have aged well, and yet when you run the blood work, these are the things that are picked up. So our challenge now is, are these just related to age, or are these suggesting that we have some underlying pathology? In addition to ageing changes.
And now what you'll see is some of the data coming out, they're actually giving us different reference ranges for different ages of of dogs and cats. And again, this just shows you that, you know, lots of things are just under the surface, but we should know about these changes. What about elevated liver enzymes?
What I'm more interested in when I'm doing anaesthesia is how the liver functions. So just don't forget that liver enzymes and cells tell us very little about how the liver will actually handle a drug. But if I'm suspicious, I would like to look at a few other things.
So if I get a a a dog with elevated liver enzymes. And a low albumin. I'm going to be thinking that liver function is probably impaired and be, you know, very careful with what I choose for anaesthesia.
But if we're really concerned, then we're gonna be looking at serum bilirubin, maybe running bile acids. But on the other hand, the dog may have presented as an emergency, and it has to go to surgery very quickly. You don't have time to do all of this.
So I often will just make the assumption. That I can't use a drug like aromazine, which isn't going to be well handled if there is poor liver function. As far as planning, again, I would try and do all the old dogs and cats outpatient procedure because of that disruption in their routine that they don't like.
It's kind of like older people, they like things just the way they are. So I usually schedule them for early in the day. Fasting, fairly controversial.
Not just in old animals, but we're starting to fast for shorter periods, and I'm perfectly OK with a very small wet meal 3 to 4 hours prior to anaesthesia. And that way the the owners could give the morning medications or give the drugs that we talked about, the gabapentin or the trazodone. Access to water at all times.
That is absolutely essential in these older pets. I only take them, take the water away when I have actually given my pre-med if I'm going to give it IM, or after I've placed a catheter and you're ready to run, as far as I know, into anaesthesia. IV access, I like to get that as soon as they come into the hospital or as soon as possible after they've been examined to get IV access.
So talking about IV excess, we know, as we age our skin becomes very thin, almost like tissue paper and very fragile, and so do our veins. The lumen becomes thinner and the wall becomes more fragile. So actually placing catheters, we can get a lot more blown veins, and we can also get skin damage due to the tape.
So this little cat on the right is actually 14 years old, and you can see, had a catheter placed, a lot more bruising than you'd expect, and also some damage from taking off zinc oxide tape, that, you know, damage there now is a site of of irritation, and the cat will lick on it, and then it becomes a site of entry of infection. So it's absolutely essential to do very good IV insertions in these pets. So clipper care, clean sharp clippers, whoever looks after the clippers in the practise, they're a very important person.
I like to use topical anaesthetic creams in the older pets so they don't flinch as we're placing the catheter, and there are several commercial ones that are lidocaine creams or lidocaine. Mixture, there are creams that are specifically for skin. They take about 10 or 15 minutes to work.
And the other thing I switched to was instead of white zinc oxide tape that really sticks, but also peels off the top layer of skin, I switched to using hypoallergenic tape in my older patients, which is easily available at most pharmacists. Pre-op fluids, I would say if you do get your IV catheter in, I would start the fluids as I'm ready to roll into pre-op area or into theatre, and then we're gonna obviously talk about how we prepare for the anaesthetic. So the anaesthetic drugs, ideally should be reversible, in case we don't titrate correctly and they have a delayed recovery, short acting because of these issues with liver function and excretion through the kidneys, titratable to effect because of the decreased requirements, but it's gonna be different in all, all of our patients, and then usually it's going to be lower doses that we're going to need in, in this pet population.
So these would be some of the drugs I would be looking at. Obviously, an opioid alone is often adequate for the older patients. Actually, we'll give you good sedation and you may not need anything else.
Although I talked about aceromazine, you know, being a long acting drug and not ideal if there's liver impaired liver function, but in other older pets, it can be quite calming, it's very anaesthetic sparing, and the doses I use are very, very low. I have been accused of being a homoeopathic anaesthetist when I use these doses, but often even less than that is all these older pets need. Dexammeatomidine, I will still use it, but at very low doses.
And then midazolam is a drug I don't use a lot on its own in young robust patients, because often they get a little bit disinhibited and act a little crazy. But actually, given IM or IV in the older pets, you often get extremely good sedation, and it can be very, very helpful in this population. And just a note that if you are going IM, midazolam can go intramuscularly, but diazepam cannot.
It can only go IV. If you do acupuncture as I do, there are other things that you can do. There are very specific calming points in dogs and cats.
GV20, we call it the happy point. If you rub there or use a needle, but if you actually rub, do acupressure, a lot of dogs and cats will get very calm. And then Ann is a point just behind the ears that you can massage, and you may be surprised how calm some patients become, and I often use these points if I'm holding an animal as someone is putting in a catheter or preparing it for anaesthesia.
Nausea and vomiting are very, very aversive, and we've talked about travel and car sickness. So if they arrive looking like this, this is not a good start. These are very, very upset animals, and they are not going to be happy, or very unpleasant, and they aren't going to eat quickly after anaesthesia.
So clearly we can do a lot with drugs for this. We've talked already about meropotent. And there is some, thought that this could actually be anaesthetic sparing as well, and it may, and I will take, say that very clearly, it may provide some visceral analgesia, but that's fairly controversial at the moment.
So it's very, very good for preventing vomiting, but I actually think on Dantron is much better for nausea, that's used a lot with in humans, and it's an antiemetic, but a very good anti-nausea drug in our pets as well. Pre-oxidation, we talked about how their respiratory reserve is, is limited, and so they they can desaturate very quickly at induction. We don't want them going blue, that's not good for anyone, including us, watching that happen.
So if we let them breathe oxygen, just normal tidal volume breathing calmly for 3 minutes, one study showed in healthy animals that decreases the time to desaturation from a a mean of about 60 seconds up to 4 to 5 minutes. So it buys you in a lot of spare time. And these animals don't have such a big reserve.
So if they will accept the mask, then I recommend doing it. If they fight it, it definitely isn't worth doing it, but as soon as they get sedate, try and get at least oxygen near their face. So for induction, you will be very familiar with a lot of different techniques, and I think just altering the drug, how you use the drugs you're very familiar with is often the safest way to go.
So for older animals, I do like to use fentanyl and midazolam as an induction. And often if they're fairly, fragile or you know, say in a hemoabdomen, a dog with a splenic mass, that's often all you'll need in order to. But alfaxolon, midazolam, propofol midazolam, very good choices.
So I'm calling, I will call this a co-induction technique. And what I tend to do is I give a little bit, but, let's say, for example, we've chosen propofol midazolam for a dog or a cat. I give a very small dose of propofol, so perhaps.5 to 1 MB per kilo.
Let it go in, then I give my dose of midazolam. And often if you just give that some time to work, that's all you need, and you'll be surprised how little propofol you use. And then if you need to give more, you can give more until you can intubate.
I've got a little asterisk next to ketamine here, and the only reason I've got that is if you have an IV catheter in place and it's a cat, I would choose an alternative to ketamine because we don't know which cats often have underlying heart disease, hypertrophic cardiomyopathy. You may know cause the dog, the cat has been diagnosed, but about 1 in 5 cats have this disease, and ketamine is one disease that makes one, drug that will make them very tachycardic and often tip that disease into a point where you don't want to go. So if I have a choice of induction agents and an IV catheter, I won't use ketamine in, in my cats.
Getting from A to B is something to think about when we talk about the slowed circulation. So we inject and we're putting it into the blood, it goes to the heart, and it goes to the brain. And think about about what we said about physiology.
We're injecting in one place, the circulation is slower, carry output is reduced in these older patients, so it takes longer to get to the brain. So what we don't want to do is like give it, you know, give an injection, and after 30 seconds we've said, OK, they need more, because what you might find is you're giving your second injection before the first one has reached the brain in these older pets, then suddenly there's nothing you can do about it, and the two doses hit the brain, you know, in quick succession. And you have an overdose.
And distance and time is important. It does actually take longer to get from a hind leg vein around the body to the brain than a front leg, so you give a little extra time. So this video is deliberately slowed down to make you get into that zen zone when you are working with these older pets, really make yourself go nice and slowly, be very, very calm, because see we're comforting this cat, and actually what we, will often see is if you go slower, you reach your endpoint after you've given less milligrammes per kilo, the end point being, can you intubate or get an airway in that cat or dog.
The other reason that we want to go slowly is from data that I dug up from humans and healthy research animals, and I've summarised it. So what they did in this study was they gave exactly the same mix per kilo to these experimental animals or people. They gave the dose in a 32nd bolus, or they gave it over 2 minutes.
And these were extremely healthy humans and research animals. And what you can see is there was a significant difference in blood pressure 5 minutes after the end of the bolus. So when you give it nice and slowly, you have less effect on blood pressure, and that is really important in our older population.
So go start low and go slow is my motto for the older patients. For the inhalant agents, we know from humans that with every decade of age, the requirement for inhalant agents drops about 6%, and these are what we call Macage charts for humans. So clearly, a 90 year old takes very little inhalant compared to a young person.
Now, is there evidence in dogs, and cats? Well, there is evidence in dogs for a decreased requirement for sevofluorine. At 2 years of age, this is the max, so how much anaesthetic is required in the lung to prevent the dog, having to be beagles from moving with a noxious stimulus is greatly reduced.
Actually, this is significantly reduced when they're older. And so again, looking at that decrease in brain mass and neurotransmitters, I for inhalant agent when they're older, and this data has been duplicated for isoflurane in dogs as well. The other thing to mention here is that the other thing that decreases requirements for inhalants is hypothermia, which our older patients are very prone to.
The other thing we'd like to do is to decrease the amount of inhalants we're using because they are very cardiovascularly and respiratory depressant, is run background infusions, and a lot of you will be very familiar with running lidocaine, ketamine. Fentanyl infusions in dogs. I'm probably not using lidocaine infusions in cats because that can be quite cardiovascular depressant, but running opioids and ketamine infusions to decrease inhalant requirements and provide some extra analgesia in these patients.
Another thing we're moving to a lot in all of our patients, but I think it's especially helpful in the older population is the use of local anaesthetics. Again, my model, think locally, but they do act globally. So doing an epidural for a major orthopaedic procedure in an older pet, and you can do this in cats too or for an abdominal procedure, is going to decrease the amount of anaesthetic they need, and going to make recovery much, much more comfortable for them.
The other thing to think about is, eyes and corneas get very dry during anaesthesia, and we usually remember always to put eye ointment in before we roll into theatre or as soon as we start the procedure. But there is good data in older dogs, especially showing that tear production is decreased with age, as well. With anaesthesia in all of our patients.
So my advice would be that you make a note on your chart to put Ilu in these older pets every 30 minutes and make sure that your recovery nurses are continuing that throughout the recovery period as well, cause the last thing you want is a coronal ulcer to add to their problems. The other thing is we already talked about changes in lung volumes, so things like the dead space where no good ventilation, no exchange of oxygen and and inhalant occurs, and the alveolar arterio gradients, they increase with age, and the FRC, which is really the emergency reservoir in the lung, that changes a little bit with age. But with physician.
But all of these lung volumes, which are going to be an issue under anaesthesia and lead to more likelihood of hypoxemia, are exaggerated in the older patient, but also greatly altered by altering the position of the animal from standing or laying internal to turning on their back. These things change dramatically, and again, put them at risk for hypoxemia. And so there is a lot of discussion in the human anaesthesia world about putting older patients because of these changes in lung volumes, in a reverse trend trendelenburg position.
So head up and feet down, but not enough that they fall off the table, and I think this can help. It helps a lot in obese animals, and I think it can help a lot in our older population. So what about recovery?
Moving into recovery, this can be where everything's gone really well. We might let down our vigilance a little bit because we think that we're sort of like we're getting there and the surgery was a success. But we know from big studies like Doctor Brodbelt's study that we talked about, the majority of anaesthetic deaths occur in the immediate postoperative period, especially the 1st 3 hours.
So that is because we're monitoring less carefully and often going from, or the animals are going from 100% oxygen to room air. So what can we do to prepare for recovery? Well, one of the things that's been shown to smooth recovery in older humans recovery is having someone they know with them during that recovery phase.
Now that's not always possible or won't be possible. For our patients, but I do try and have the nurse that was working with the animal when it came in and doing the anaesthesia be the same person who then recovers cause the animal may have bonded with them, and they may have a very common influence on that pet. The other thing is, how do you set up for recovery?
We mentioned the harnesses in the dogs, so it, it would have come off for surgery usually unless it was a dental, may have stayed on, but it goes back on. So we can move them around, help them get up when they want to get up. The other thing is, absorbent.
Fleece, because they may be wet or urinate, supplemental heat, they're gonna need. I like a raised bed so that urine can drain, and I do encourage everybody, all the owners to bring in a familiar toy, blanket, or piece of clothing of the owner to keep with the animal throughout its time at my clinic. So there's the little lamb that is that dog's favourite toy, hoping that it helps console it in recovery.
One of the biggest causes of discomfort and agitation in the recovery period is either a person, you may know this yourself, or a pet waking up with a full bladder. This is extremely distressful, uncomfortable, and cause a lot of agitation. I've been asked to go look at animals that are recovering, not very well, and everyone says, I think they're painful, they need more sedation, and what they really need is to urinate.
So I usually have my surgeons express the bladder if they're doing an abdominal procedure before they close. And if we're not, we actually express the bladders prior to going to the recovery room and it's on our checklist. If there are a major case, then obviously putting in a urinary catheter is gonna help nursing care and comfort of that.
Other things that will cause total disruption and agitation and recovery is our bright lights, a lot of noise, a lot of staff activity, and then monitors going off and so on. So we want to recover in a nice, if possible, quiet area, and that could be hard, but it should be enforced, dim lighting, minimal activity, and so on, and I think that can get this very agitated dog to turning into this dog that would just like to sleep. And heal, but it's still arousable.
The other thing is, we do know that there's disruption to sleep patterns caused by anaesthesia, but also by age. And one of the reasons is that older animals don't have a surge of melatonin late in the day that is stimulated in young healthy animals by light. And so often this is one of the reasons why they don't sleep well, and in a clinic where there isn't a normal exposure to sunlight or a normal daily dark and light pattern.
It can cause a lot of disruption, these animals become exhausted. It's well recognised and humanised to use this loss of normal daily rhythms will cause a lot of fatigue and restlessness. So I actually have started recommending melatonin in older pets and in pets after anesthes.
These are not a lot of good solid data here, but these are the doses that, that I recommend. And I just want to point out that a lot of the ones that you go and pick up on the supermarket or the pharmacy, they do contain Xylitol, so be careful to recommend a non-Xylitol containing supplement for dogs. Delayed recovery.
The number one cause is hypothermia. This chart is research data from actually from Australia that shows there's a clear relationship between the temperature that they leave the the theatre at, and how long it takes to sit up and be extubated and sit up, it's very, very clear. So the warmer they are when they come out, the faster they're going to recover.
The other issue with recovery is if they have got cold, they will start to shiver. And remember I said that the older pets, less muscle mass, can't generate as much heat, so shivering is going to not generate as much heat, so they take longer to heat up. The other thing is, all that muscle activity increases oxygen demand by at least 200%.
So any animal that is hypothermic should be given supplemental oxygen until it is normal thermic, so we don't have hypoxemia. What about reversing drugs? I'm a big fan of midazolam as my one of my co-induction agents, but we do know it's likely to last, quite a bit longer in our older patients.
And again, I might have titrated, but if I think that is the reason that they're not waking up and there's something I could reverse, I would go ahead and reverse a benzodiazepam, so midazolam ordazepam. So which of the drugs, and this is your, your last polling question, which of these drugs would be the drug that would reverse either midazolam or diazepam? Right, folks, your questions are open on the screen.
Feel free to click on the one that you feel is the correct answer. And then like earlier, we will reveal those results when the poll is closed. Quite simply, which of the following drugs would reverse a benzodiazepine?
Naloxone, attiammazole, flumazin, I got my teeth out tonight. Doxopram or your hemine? Right, another 10 seconds or so.
A couple of strugglers still coming through. We'll just give them a few more seconds, Sheila. Right, so let's end that poll and share those results.
Oh, you guys are good. OK, so the orange line is the winner, and that is correct. And so I'm on to the next slide and Flumazanil is the reversal agent, very specific reversal agent, and I'm just going to show you a video of what I call a grey muzzle dog, where I'm using flumazanone and I'll talk you through what we're doing.
So this dog, as you can see, grey muzzle, warmed, no longer shivering, warmed up, you can see the bear hugger there in the background, but just wasn't waking up. Review the anaesthetic record, and I go, well, you know, the one thing we could reverse is that midazolam. So what I'm doing here is I'm just giving it to effect, and I'm looking for increasing jaw tone, maybe a swallow.
So I'm not, I'm just looking there, checking, is it, yep, getting tighter there. And I just want to give enough to allow the dog, there, there's the swallow, so I can pull the tube. And be sure you got good airway control, but still, you know, will listen to me, but just wants to go back to sleep.
So that's what titrating the reversal agent looks like. And then we're just going to go to one more, and this is our last thing we're gonna look at before a very quick note on sending these pets home. So this is Benny, and Benny had been given a fentanyl infusion during a CT procedure.
He had horrible osteoarthritis, but he was going for CT and he worked up for for surgery. So here is Benny, in recovery. And so you'll see what his behaviour looks like.
So he's actually yipping and barking. My resident is trying to talk to him. He's what we call out to lunch.
He's not paying attention. He's being restrained here. So she's given something and she's titrating it in and waiting for him to become more alert and normal.
So now, he has become mean, you know, like calm, wants to sit with her. He actually knows his name now. So what this actually was, was dysphoria due to, opioids.
And a lot of people are very concerned that they might mistake dysphoria from pain. Well, we had, we palpated his abdomen knew where that that there was a problem. Even if they're dysphoric, if you do your exam for pain, you can usually differentiate.
But dysphoria is related to a lot of opioids being put on board, this kind of completely out to lunch behaviour. And what we're doing is we're not just choosing a dose of reversal, and the reversals for opioids are or certainly a fentanyl infusion, bearphennol or naloxone. We're not choosing a dose and giving it all.
What we're doing is we're using bearphennal or naloxone. So on. Diluting it down, I just suggested 1 in 10 with saline.
You just give a little bit, wait 30 seconds, give a little bit, and that dog or that cat will suddenly start acting normally. It's like one molecule was knocked off the crazy centre in the brain, and you stop. And that way they're behave normally, but you haven't reversed the analgesia, so don't be afraid of that.
And then just to finish up, these dogs were completing and cats were completing that circle, and they're going to be sent home. So oral medications, we might consider non-steroidals in cats and dogs, codeine, paracetamol combinations, certainly only in dogs and never in cats. I'm getting a lot more enthusiastic to think about the male.
Melatonin, neropotent, maybe for another day, to make sure their appetite is good. There is data to show that neuroppotin does does decrease the first time to voluntary eating and increases, caloric intake on the first day of surgery. And then what other things we could do.
And the one thing I'm going to end with is one of the things that I think is most underused for analgesia in the clinic and at home after surgery, and that is cold therapy. These owners can do an awful lot of good to their, for their pet by icing incisions. So they can buy these gel packs so you can dispense them.
I Usually, if the animal is normothermic, start applying this to the wound during recovery. We know it decreases pain, decreases swelling, and there's a lot of data to back that up. So that's another thing to think about for sending home for full comfort kit, when they get home.
So we have completed this cycle, and I know I've taken up, the whole time. But if there are questions that I can answer now or later, I would be more than happy. But hopefully, I've given you some tips.
There weren't, none of it was rocket science, but how you think about your older patients, and some of the little tips to make their life a little bit better when they're with you in your clinic. So thank you so much for listening in, hopefully on a nice evening wherever you are. Sheila, thank you so much for your time.
That was absolutely amazing. And you know, you say it's not rocket science, but it's actually more important than that. It's the way you've pulled it all together and I think that that circle from home to home is an unbelievable concept when we're dealing with any animal, but especially our old babies.
Well thank you for those comments. That's really great. I also like to comment about knocking a molecule off the centre.
I'm I'm gonna try and figure out how to do that in some of the staff as well I think sometimes. Folks, if you have any questions for Sheila, please feel free to just pop them in the Q&A box and they'll come through to us. But Sheila, I think you've done such an amazing job that you, you really have given everybody so much to think about that, you know, it's hard to come up with questions, when, when the talk was so incredible and and and so comprehensive.
So thank you for that. Yeah, well then we'll maybe challenge some people if they want to do my multiple choice questions at a later date. That's it.
And that's it, folks, with the recording, we will be loading up the multiple choice questions from Sheila. So if you want to go back and watch this amazing talk again, I'm sure you will gain just as much the second time as you did the first time. And then there will be also some multiple choice questions which will get the old grey matter thinking.
So Sheila, we've got a lot of comments coming through at the moment. Not questions so much rather just thank you, that was amazing. Perfect tips.
What a great webinar. So informative. Thank you very much.
So everybody's agreeing with me. Good. Yeah, I mean it's I think I mean, we have a little special place in our heart for the grey muzzles and the older grumpy cats, I think.
Yeah, I think so. Max has posted a question and said we use a lot of buprenorphine in our clinic for procedures that don't quite warrant methadone. Is that OK?
Yes. I mean, I, I, I mean, I'm a huge fan of, buprenorphine. I tend to use it a lot more in cats than I do in, in dogs.
But I think it's an excellent analgesic. When you, and when the question came in, clearly, Max is thinking about how he's using it, cause when he said it doesn't just quite cut it for methadone. So I'm assuming that if it was a major orthopaedic procedure, they would be getting the methadone.
But I think for a A lot of soft tissue, cases, then I think the buprenorphine is, excellent. And, you know, you get some, you know, some nice mellow dogs and cats with that, and it is longer lasting, but I don't think I see, huge, like older dogs and cats being more unded on it necessarily. And people think it can't be reversed very easily, but actually a little bit of butterphenol or the naloxone like I described, if I, if you were worried that an older pet was just like too obtunded and you're sure it's that job, you can actually cause a little bit of reversal.
Excellent. Carolina wants to know what dose of LFK CRIs would you use in the older patients? OK, so lidocaine, fentanyl, and ketamine.
OK, so I'm not gonna answer that right over the wire, but that's something I could send to you to poster to do that. I use a lot. I would not use lidocaine infusions at all in cats, period, regardless of their age, because it is cardiovascular depressant, it's good data.
But I'll use, an opioid infusion with ketamine and cats and dogs, and then add the lidocaine in the dogs. But there are so many different recipes out there, I would tend to, certainly go on the lower. End of the recommended range in the older pets.
But if during the procedure, you can tell that the heart rate and blood pressure seem to be, responding to what the surgeon's doing, then just like any patient, you're going to alter the dose. So every animal is going to be a little bit individual. But after you stop those infusions, they tend to like the, the plasmin levels tend to come down, in a nice, nice and quickly, but again, I think the one that sometimes causes the dysphoria, especially in the older pets, is the fentanyl, as I showed you in that last video of, of, Benny, if they've been at a high dose, we turn them off, then they behave like that, that sometimes can be dysphoria and not necessarily pain.
Yeah, and I think your statement there about individual formulas is so, so important because you know you can get a 15 year old cat like your baby you showed us, who has got incredibly low muscle mass and you get another one that is actually quite well muscled and that would be two completely different dosing regimes. Yeah. Yeah.
And just thinking of like the graphics I had of the, you know, the muscle sink, and then the fat sink, you know, which clearly my little kitty didn't have many of those sinks left for his drugs to go to. So, very different from the sort of, you know, lumbering older Labrador that waddles into your practise. Sheila, that's about it for this evening.
More and more comments coming through about what an amazing webinar that was and how informative it was. And it's up to me to once again thank you so much and to say please, please, please come back again. We'd love to sit and listen to you some more.
OK, I think that's in the in the in the works. So that's excellent. So folks, that's it for tonight.
To Rich in the background for all your help controlling things. Thank you very much once again to our wonderful speaker. Sheila, thank you for your time tonight and to all our people who attended, thank you for the time.
You can now go and watch the football World Cup and that's from my side, it's good night. And for me. Bye bye.