Thank you very much, Caroline. Thanks. And I, I, it's actually very difficult to say bandaging angels.

I have to, I have to admit. So thank you very much, everyone, for joining us, this evening. It's a privilege to be here, and I'm gonna be, spending probably 50 minutes or so just really giving you a rear vision.

Oh, I think I've got a slide just to explain what, this session was gonna cover. But really, the revision of the process of wound healing, illustrating the phases of healing and what we can, how we can optimise those, some of the factors that cause healing delay. I might challenge a few assumptions, we'll see how we go.

But really, to highlight how important it is to understand the natural process of healing, so that we can really, identify. What's going on when people are asking us, telling us that they've got new products here and there, and they're gonna do magic things. Obviously, my background was in human healthcare, and wound management and technologies, and there's an awful lot of pseudoscience out there, and there's a lot of hope that we put into these products to help us fix things that actually, given the right environment, these things can heal quite well.

So, really that's what I'm gonna hope to cover during this session, and there's an opportunity for questions and answers at the end. So if anything doesn't make sense or if you've got questions as you go through, please, please just ask. I thought I'd open this session really, with a, a slide, about Ambra's parare.

Now, that's another word that's, he's another name that's very difficult to pronounce. You may or may not have heard of this gentleman, but, he was an army surgeon. He was actually a barber surgeon.

So barbers were the surgeons of the time, and he got a reputation for being quite a, forward-thinking. Guy for, medicine, surgical techniques. He actually authored quite a few books.

He's got quite a lot of, forensic and pathological experience in terms of, management of, surgical wound closure. And he was asked to go to France to, Sorry about that. He was asked to go to France and, manage some of the wounds from the battlefield.

And as we have today, a lot of the technologies that we have available and the advances in wound management that we have are really, born out of the battlefield, and the same was at the time. So, the interesting thing about this guy is he used what was one of the most modern technologies of the time to manage the wounds in the battlefield. And that technology was actually boiling oil and tar.

And they would cauterise the wounds by pouring boiling oil and tar on these poor soldiers. And at one point, he, ran out of this stuff, and he was in despair, not knowing what he was going to put on these wounds. So he referred to one of his Roman textbooks.

And he was surprised to find a, a balm that was a recipe for a balm that he could make to put on these wounds. And that was, egg yolk, turpentine, and rose oil. And he thought, this, this is never gonna work.

So he went to his room, made this up this, balm of, rose, rose oil and turpentine and egg, egg yolk. And he put it on the wound. And he found the next day that these wounds and the soldiers were a lot happier than the ones that he'd cauterised with the liquid pitch and boiling tar.

And it was at that point when he found that these wounds healed better and that these men actually, had a much better quality of, quality of life with that treatment, that he decided that he was the one to dress the wounds, but it was God that heals them. And it was a very, it's a very poignant thing to say that, he certainly dressed wounds. He used to think that he knew it all, he had all the products, he had the technologies at his disposal.

And actually, when he stepped back a little bit and allowed the wounds to heal, and he used, the dressings to put on these wounds, he found that these wounds were physiologically healing much better than actually he had appreciated. And I think it's just the same today. We still see technologies.

We see a lot of products out there that are aiming to help us heal wounds, but sometimes we forget to trust the process itself. So that's really what I wanted this, lecture to be about. What you may find, may think is, modern technology today, we may look back in 100 years' time and think, I can't believe we, we ever put that stuff on these wounds and these poor patients.

So, one of the questions really, before we get into the physiology of it all is, why do we bother to try and manage wounds anyway? What's the point of understanding physiology? Surely we can just, sort of stand by and hope that these wounds will heal.

In fact, 80% of wounds heal despite what we do. So, a lot of the time we're getting positive reinforcement of what we did worked, when actually, maybe we could have done things a little bit better. So, the physiology of healing, the, the actual aims of wound management, are the same sort of across all mammalian sort of species.

So in humans and, and animals. And really, we're aiming to achieve these three things. I've tried to illustrate it the best way I can, but really, they are a functional cosmetic repair, relief of pain and distress, and a rapid return to normal use.

So, really, I've used an illustration here of human, wound healing challenge, human wound healing challenge. Which is that in humans, we get this, contracture where scarring, healing may progress very nicely, but actually it's the contraction and the scar tissue that actually causes the limb not necessarily to function as well as it could do. So we may get the repair, but we may not get the function that we, we're aiming for.

Similar things would happen in maybe an abscess at the side of an eye in a dog. You may get a lovely clean abscess, but if you allow that to close by second intention, you may find that that, process of contraction actually pulls that wound, closed more than you'd like, and the eye may not have the function that it does. So we need to look at how How do we achieve a functional cosmetic repair.

Cosmesis may not be so important. Certainly, I don't think, people are quite so worried about the scarring effects unless they happen to have a dog that's showing, and in which case, even your best efforts are never gonna be good enough. So, function is probably more important.

Relief of pain and distress. So what we want to do is make sure that the animal is comfortable, that actually, if it's a stressy animal, stressy patient. That we are following a management plan that works for that patient and that client, obviously you can have a client that's highly stressed as well.

That isn't helpful, for, for the, the whole process and is, is driving you crazy, interfering with wounds and otherwise. But I've got the caged dog on here as sometimes, an animal can't tolerate being, housed like this. And maybe if you're trying to salvage a limb, you might find that actually the animal's better off on three legs than it is trying to salvage something that is going to take months and months to heal.

And then finally, as rapid return to normal use, I don't think there are many pirate dogs out there, but, just to show that, you can quite happily live on three legs and go to fancy dress parties, dressed as a pirate, which I think is rather fantastic. But, certainly, getting that animal back to normal use is probably a priority. So we use these three, objectives, really.

Three aims. They're always in the back of my head when we see a case that's submitted to the veteran library for support. The question is, how long has this case been managed?

What are the challenges that are this patient is facing? What are, what's the history involved, and really, what outcome is the best possible outcome for that patient, rather than what can we do if we've got everything at our disposal. Now, the final part of this, really, which isn't listed here, really, is that we need to do this at a cost that is, acceptable, to the owner.

So sometimes you can do anything if you've got enough money, and the question is whether that is going to fulfil these three aims of, of wound management. So I thought I'd try and start from the beginning, and I hope I haven't been too too clever here, but I, I was trying to be, so we'll see if it works. We've got, here a little bit of, skin, a lovely cross section of the skin showing the epidermis and the dermis.

So, I often do talks for vets and vet nurses at the same, and people will come along and say, Well, is it suitable for vets and vet nurses? And I always say, Well, the process of healing is no different, whether you're a vet or a vet nurse. So, really, the structure of the skin is not gonna be any different, whatever your background.

So it's absolutely fine. I always think to go back to basics, because I wish I'd gone back to basics at times. And these sorts of things are the things that maybe are studied at 2nd or 3rd year, and really, it's your chances of, sort of having the time to go over it again are quite minimal.

But really, it comes down to the fundamentals when we start to look at wound management and the impact that wounds have on the skin. So we've got a lovely cross section of the skin here. I don't know if I can draw on it, but we've got the epidermis, which is the top layer, the more purple layer.

The epidermis is made up of lots of different strata or lots of different layers, which are, is fed by, I think this should come up, the basal layer or the layer of caratidocytes, these columnar epithelium, which actually are the margin between the dermis and the epidermis. So this top layer of epidermis is actually made of, lots of these cells, which actually shed, and they create layers of this strata, which are shed over a period of weeks to, months. I believe it's 14 days or so in dogs and cats, and maybe, I may be wrong, that may be horses.

And it's certainly 28 days in humans. So depending on, on your species, this can take, take longer or, or slower. So your top layer of skin is actually your waterproof layer.

It is your defence against the outer world. It is actually the layer that it is a dead layer. It doesn't have any blood supply of its own, but the blood supply is actually supplied by the dermis, which is beneath that layer of basal cells, and these blood vessels here, they will actually supply all the oxygen nutrition that these cells need to survive.

Take away the oxygen and nutrition, cause ischemia, bandages that are too tight, or areas that have got no blood supply due to trauma further up, and you'll find that this epidermis will start to slough away and you'll end up with wounds that are quite, quite hard to, to manage. You need that blood and that vascular supply in order to Support that basal, basal, layer of caratnocytes to make this, useful defence, against the outside world. So let's not forget the skin is the biggest organ of the body, in any species, and it serves a very, very important purpose.

So one thing that I missed out from this, from this lovely slide is that we don't have a hair follicle in the middle. And this is something that is actually really important. It's something that doesn't reoccur once you have a wound that has closed by scarring.

So when a wound, you have a large wound and it heals from the edges inwards, you can't replace these hair follicles. Also, when you note a hair follicle, what you should see also is, or, let's see if it works. Yes, ideal.

Thank you. Is that you've got this basal layer that will curve around the base of the hair follicle into deeper into the dermis. And this is why you sometimes see wound healing, or a, partial thickness wound that goes through sort of most of the epidermis.

But if you've got little remnants of hair follicles, you've actually got some remnants of these keratinocytes, which can be areas where these epithelial cells can begin to proliferate again. So, If you've got burns that actually only go through partial thickness and there's still a little bit of hair follicle left, you've got a fantastic little island there of tissue that could produce new keratinocytes that will actually start to migrate sideways and will start to fill that gap. So, always look for those hair follicles.

If you can see what looks like stubble in something like a burn or chemical burns or abrasions, then chances are you may have healing much more quickly than maybe you thought, otherwise. So the other benefit of these hair follicles is that they have sebum, and they will produce the oils and the fats that the skin needs in order to make it, antimicrobial. It creates the waterproof defence, and it means that the skin can be a lot more, robust and maintain its elasticity over time.

So what I'm getting at. With all of this stuff is that, the skin with a hair follicle provides an awful lot more than just hair, but it's also providing a lot of oils and a lot of the, essential, defence that the, the skin needs in order for it to be robust and elastic for, in time to come. So, This is really why if you have the choice to do reconstruction, or you have the choice to graft, or you have the choice to get, tissue to migrate across your open wound bed, then actually, you will have a much better, tissue at the end of it than if you allow this wound to scar, which is actually more of a second class type of tissue, than actually hair follicle, tissue with hair follicles in it.

So, what I'm gonna do, I think I was gonna illustrate, a big wound there, a catastrophe in the wound. Wound is a break in the skin where it can go through either epidermis or dermis, or it can go further through into the hypodermis as well, which will mean it's gone through to the fatty layers. And obviously, you can go down to.

Muscle, bone, tendon, depending on how dramatic that wound is. But really, the wound healing part that we're interested in is once we've got a granulating wound bed, how this dermis and epidermis fill the gap and fix what, what is missing. And this is the, the magic bit of wound management.

So we've got 4 phases of wound healing, which are pretty much written in the textbooks. Depending on which textbook you've got, you will get different descriptions and even different, different order of things. Maybe a lot of textbooks will say, phases of healing start at inflammation, proliferation through to maturation.

So they'll say there's 3 phases of healing. Personally, I prefer to mention hemostasis because it is an extremely important part of the healing process, and there are factors that are involved in hemostasis that are critical for the production of inflammatory cytokines and messengers that are going to start to, enable this wound to clean itself up and help itself move along. So hemostasis, this is a picture of a horse I used to own that managed to, well, I, I owned it until he passed away, bless him, but he survived very nicely after this injury, and he managed to impale himself on a little bit of of metal.

It was over his rump, so it had plenty of muscles, so actually, it healed very beautifully because there's lots of vascular supply, plenty of tissue there, lots of contraction. But actually, the bleeding stopped within 10 to 15 minutes. And as we started to see the clotting process begin, what you start to see is that the wound produces exudates.

And these, the plasma that is leaking from the wound contains white blood cells. Platelets stick to the site of injury. You can see in this image here, that's a load of platelets stuck to an erythrocyte.

They are little like, little capsules that start to create extensions and join up together. And as the blood clots, and they stick to the site of injury, they stick to the collagen fibres, we're all made up of about 80% collagen. So they stick to all these severed fibres, and then they start to release their contents into the wound.

And as they do that, they start to stimulate all manner of different, messengers and all manner of different, processes. That are absolutely, vital for normal wound healing progression. So this is why hemostasis is important.

This is why platelets are important. If you have an animal that doesn't have platelets or for whatever reason, they're not functioning properly, you will have a delay in the response to healing. You won't have inflammation in the way that you, are potentially expecting it.

That animal is going to be compromised in terms of its healing, ability. So here's a, a little, chart that's actually got, all sorts of these different cytokines in, and all these different messengers that are used, by the body in order to aid healing and facilitate good remodelling and, the provision of new tissue that will fill the deficit and fill the gap that's been caused by whatever trauma it was. Now, there's lots of research goes on into all these different cytokines.

Everyone would love to have one of these cytokines in a tube with high. Gel to say, OK, you put this on the wound and the wound's gonna heal despite everything that's going on. You stick this interleukine, factor in there, or a, crikey, there's all sorts of them.

Epidermal growth factor, PDGF, platelet derived growth factor, VEGF, I think that's, oh, crikey, I'll forget them all now. But really, they were vascular endothelial growth factor. So they're all gonna start doing all these amazing things and switching things on and off, but actually, you need them all, and they have to all be in the right order in order to work.

So you can see there's different cells there, platelets, mast cells, polymorph nuclear sites, monocytes, macrophages, all the way to fibroblasts. All of these different cells have different triggers and different factors that they will be switching on and off as the wound is progressing. And they all have to go in the right order in order for a wound to progress normally.

This stuff has become so complicated that honestly when you start to look into all of these different growth factors, it's an absolute myriad of different, Different mathematical looking, equations and, words that, most of us, really find quite mind-boggling. But generally, they are a complex process of events that none of us yet know how they all work, in detail. So, my best way of explaining how these work and really sort of the importance of them, and really the importance of not interfering with them and damaging them.

Is that it's very much like a city that is controlled by traffic lights and all the different, things that are going on and off in a city in order to create, a civilization that is, in tune. Everything works as it should do. People can go to work.

The whole thing is, finely tuned so that, the city runs smoothly. If you start to mess about with the traffic lights, which is just one element, you'll find that the city very quickly goes into chaos. And that's exactly what happens here.

So if you start to use products that damage monocytes or macrophages, you switch off an awful lot of these cytokines and you will affect, the healing process. Again, with fibroblasts, a similar, similar scenario, the fibroblasts are there to lay down collagen, to help with remodelling during a proliferative phase of healing, and you start to mess about with those, and you will affect wound contraction, you will, also, mean that you're, Tissue won't be as robust, and you may, actually stop, cell migration. So all of these things can be influenced by different products, things that people say are natural, things like tea tree oil, which is urine for diol.

It's a phenolic compound that is toxic to cats. All of these things can interfere with these cells. So, it's best to do no harm rather than put loads of things in wounds that you think may actually do some good when actually they're knocking out some of these very, very important messengers.

And then these messengers are carried in a sea of exudate if you like. So we have different types of exudate in wounds early on in the healing process. You might see nice clear exudate, serous exudate that is kind of straw coloured a bit like what you'd see in a blister, which is in the top picture.

You may have sero purulent exudate, which is sort of cloudy, it may be quite smelly, and you have different types of exudate that, you know, in the back of your mind, if you see a purulent wound with purulent exudate inflammation around the edges, and it's got a smell and the patient is, showing signs of systemic, illness, you know that that may well be a sign of, infection. So exudate. Tells us an awful lot about what's going on in the wound.

And describing exudate is really important. One of the things I, my little joke when I go to practises is often that I, ban the word pus. And the reason for that being that if you use the word pus, other than the fact that I don't know anyone who can spell it properly, is that, pus infers infection when actually, a lot of these wounds can be fluffy, but they're not necessarily infected.

So, actually, this cat here, this is Got fairly fluffy wounds, but this was actually after removal of a bit of necrotic, tissue following an abscess, a burst abscess. And actually, there's no redness, no swelling. And once you remove all that, fluffy sort of discharge, actually, the wound's beautiful underneath.

This wasn't infected. It was actually, a very nice, healthy wound that went on to heal beautifully once all that debris was removed. So exudate.

It contains an awful lot of things that we need. And the principle, of moist wound healing, where we, now know that if you keep a wound bed moist, so you debride it first, you get rid of as much as the dead protein and stuff as possible, and then you maintain a moist environment. It enables exudate to, do what it needs to do and support the normal functions that are essential for wound healing.

So we've got some things in here. We've got, Macrophages, or glucose tools with these different, proteins, proteolytic enzymes that are gonna break down proteins. They're actually gonna help us debride all the dead stuff from this wound so that we can aid, rapid formation of granulation tissue.

So after hemostasis we've got inflammation, and inflammation is, begins really, after, the platelet aggregation and all those chemical messengers. It should begin within hours after injury, you'll see initial vasoconstriction followed by vasodilation. So you'll get the redness, the swelling, the heat, edoema, and an increase in exudate provided to the wound bed, which is obviously going to be why you've got, this wound here full of bacteria, but also macrophages.

I can't remember if that was, no, it doesn't do anything. But that wound will be bathed in a, in its own exudate so that those macrophages can release their proteases and engulf these bacteria in the wound and aid in the debridement of this wound naturally. The only thing that we can do during this stage of healing is to aid the process along by removing the bulk of dead stuff.

And, this poor person with a splinter in the back of their foot, you can see there that they've got a nice big foreign body in the middle of their. Now, you wouldn't dream of putting your sandals back on with that sticking out of the foot. You would remove your splinter and clean that wound up.

And actually, you'd expect that wound to heal quite. Nicely. But on the same level, when we've got a wound that's full of debris and grit and dirt, if we don't remove all those, micro, sort of microorganisms and all the sort of the macro dirt that's in there, and the best word for it is bio burden.

It's all the dead stuff and bacteria and fungi and stuff. If we remove as much of that bio burden as possible, those macrophages won't have to produce as Much protease, activity, or they won't have to be quite as busy, and because they're not as busy, what will happen is that they won't stimulate the inflammatory process to be more prolonged, and your granulation tissue will begin more quickly. So, our, our ability to clean wounds, to lavage, to get rid of all the dead stuff is probably one of the most powerful things we can do when managing wounds.

And I know people are often I'm sort of laughing at my silly stories about flushing toilets and things, but I'm always saying, flush the toilet, and then you can spray your bleach in the toilet as a finishing sort of antimicrobial effect to kill off any residual bacteria. And it's exactly the same in wounds. You should flush plenty of volume first, get rid of all the dead stuff as much as you possibly can, and then, then you can start to consider whether the antimicrobial burden is going to be a risk for this patient in terms of infection or deterioration of the wound.

But even Hippocrates, 400 BC, realised that if you take the dead stuff out of a wound, that wound will go from being yellow to being a granulation, a healthy, healthy wound bed that's red, vascular, and ready for reconstruction or ready to close. So that's what That's what we're doing with this, in the inflammatory phase. Focus on getting that wound bed clean.

And you don't need to, you can change the dressing daily, until you start to see that healthy granulation tissue, which should start to form at about day 4 post-injury. So. Inflammation usually peaks 24 to 48 hours after trauma.

Quite typical to see a wound that starts on day one. Maybe you've cut yourself and you think, Ouch, that hurt. You stuck your finger and think, Well, it's a bit of a paper cut, but I'll survive.

And then 24 to 48 hours later, you're sort of sat. There in the garden thinking, My God, my finger hurts and it's red and it's swollen, and it's throbbing, and it's got a bit of exudate. And usually what I'm thinking is, wow, that's amazing.

That's my healing process at its peak, and I can guarantee after day 4, the redness will have subsided and, things will be well on their way. So something that I do get on my high horse about, these days, a little bit is identifying and, differentiating between infection and inflammation. So this is why I don't like the word pus.

You can see in this image here that you've got an orthopaedic, reconstruction here, so you've got some orthopaedic implant there in a, in a dog. And you can see there that there's quite a lot of slough produced. So anything that's yellow, anything that's fluffy, you can pretty much guarantee you've got inflammation.

That is the clinical sign for, for inflammation. However, around the edges of this wound, it's not particularly red and inflamed, it's a bit red around the edges. But, it's actually stalled because there's probably biofilm on that orthopaedic implant.

Chances are you're not gonna be able to get this wound to progress until that biofilm or that implant has been removed. So, the challenge being, it's not necessarily infection, but it may just be chronic inflammation caused by whatever is, inhibiting that wound from healing. So the question is, do you use antibiotics or don't you?

It's obviously an individual case by case basis. It's very difficult and very, it takes a lot of guts to, to not use them. But really, if you see inflammation, Think logically, what is that inflammation there for?

Why is it there? Is it foreign body effects? It's often necrotic tissue, dead tissue, foreign body that is the cause for prolonged inflammation.

Infection is just the subsequential, the outcome of that heavy bio burden. So rather than thinking of infection being the problem, think what the bio burden or where that source of chronic inflammation is from and deal with that, rather than just jump to the conclusion that it's infection. So, I thought I'd put a little slide in about, optimal wound healing, this, moist wound healing principle, this magic sort of, phrase, that in human healthcare they call advanced wound care.

It's nothing to do with using clever bits of kit. It just means that you are managing a wound in the fashion that maintains a moist environment to optimise healing. So this picture of this poor lady with her leg ulcer there, she's got a pretty horrific, leg ulcer.

The principle's exactly the same. To bride all the dead tissue, get rid of anything that I know Derek Nottenb, who's an equine specialist, would say, the pizza principle, you need to get rid of anything that's burnt or cheesy, and you need to then, encourage. Your tomato base and your lovely epithelial crusty margins.

So your nice little epithelial margin. What we don't want are stuffed crusts, because that would be an abscess, and we've got to get rid of all of that stuff. So I can, I can hear half of you probably vomiting over your supper, but, you know, I know you're, you're ill and all in the veterinary profession, so it's, it's never a problem.

So, really, we're looking at removing the biburden and then maintaining a moist environment. The hydro gels that you use, probably most of you have got a foam, maybe have got a foam dressing and a hydrogel. I know certainly in the UK, a lot of people have got this in their dressings cupboards.

These products were invented to maintain this moist healing environment, the hydrogel being mainly. Also with a gel that holds it in place so it doesn't sort of roll away. And the foam dressing has got a permeable, semi-permeable membrane that stops too much evaporation of moisture, so that, that, when it's in place, it maintains some humidity.

And the theory is that if you can maintain a moist environment through, our After debridement, through inflammation, through granulation, you will get faster epithelialization, sorry, faster epithelialization, better tensile strengths, and a smaller scar because you will get 50, 30 to 50% faster healing and faster cell migration, than if you were to leave it open to the air and allow it to dry. So. Obviously it's a very difficult when people say to me, I let the air get to it, or you get a wound that is granulating a bit like this one, and they say, actually we can't keep a bandage on, or that, something like the hydrogels will cause it to over granulate.

Sometimes you can make wounds too wet, sometimes they can be not wet enough. Sometimes the bandage itself can be more of a problem than keeping that wound, moist. So you have to make a kind of an educated decision based on the risk benefit.

So if the bandage is causing more problem than the wound itself, chances are it's best just to get rid of the bandage. The main, The main advantage of using moist wound healing, certainly in human healthcare, is to try to reduce healing time, reduce the incidence of, appointments so that you don't have to see the patient more often because you can leave the dressings in place for longer, but also to, get a better scar and a, a small. The scar than you otherwise would do if you left it open to the air.

If the client's not that bothered about the scar, then, you've got to weigh up, sort of the management, of with dressings versus management open. So it's, it's, we're just looking at ideals, in that, in that circumstance. The proliferation, starts after your inflammation has subsided, so this wound should be, is about a couple of days old.

At this time, post 48 hours, this was an RTA, where the cat disappeared and then the wound was cleaned up and, they used, actually used a honey dressing to have. Clean that wound up because it's osmotic, it's also antimicrobial. And then a hydrogel to encourage, granulation tissue formation.

And hopefully it should start to granulate in front of your eyes. And you should see that after about 55 to 6 days, you should start to see a healthy granulating wound bed fill this wound, with lovely vascular tissue. That is going to be an ideal, substrate for your epithelial cells to migrate over the top.

So what is actually happening during proliferation is you have got, in this, picture down at the bottom, you've got lovely vascular tissue that is filling that wound bed. And this vascular tissue can't just, grow into that wound, without a matrix or something to grow into. Think of it like scaffolding, on the side of the house.

You sort of be, quite vulnerable if you tried to clean the windows upstairs just by hanging on, to the guttering. So, what actually happens here is fibroblasts that, start to appear at about, sort of, well, quite early on, during healing, they will lay down collagen, and they will lay down these fibres quite randomly, so that they act as a scaffold, as a matrix for granular new, vascular tissue to grow into. So that vascular tissue will start to cling onto this collagen matrix that these fibroblasts lay down.

And as that vascular tissue builds from the bottom of the wound up or from the edges of the wound up, those fibroblasts will remodel that collagen and build another layer, and will keep going and keep going until we get to the top of the wound, and that epithelial margin will start to meet that granulation layer and that new granulating bed. That will almost trigger a switch. That means that those fibroblasts now know that it's time to begin wound contraction, and some of those fibroblasts will turn into myofibroblasts, which will have contractile properties, and they will start to pull the edges of the wound together so that that wound will start to contract and start to shrink.

And you could see these wounds shrink by up For between 30 and 70% of their original size, depending on where they are on the body. So, if you've got a wound to the limb or a wound that is a large circumference of the limb, a bit like this one in the, in the image, you may actually only get 30% wound contraction because, one, the tissue isn't very elastic, and two, there may not be enough tissue. Available around that wound for it to pull the edges inwards enough to close that wound.

Whereas if you've got a wound around the neck, sort of abscesses around the neck, that, that burst and you clean those out, and they're full of lovely, healthy granulation tissue, once that begins to granulate from the bottom up, you can see these shrink massively so that they, what may look like a horrific wound. Looks fantastic a week later and everybody thinks that's whatever you put in it was amazing, but actually the granulation tissue is doing exactly what it should do. So these cells, I'm, I love these fibroblasts because they really are the, the guys that, save the day in terms of filling that, enabling the wound to fill up with granulation tissue and aid wound contraction.

And the sad thing is that we can kill them quite effectively by using chemicals such as chlorhexidine, iodine, anything that is a potent antimicrobial has the ability potentially to damage some of these cells that are essential for these processes to occur. So certainly, in a lot of equine wounds, we've seen horse owners who've got hippie scrub on the yard, who are, trying to keep the cost down by bandaging their own. Horse, so maybe the vet practise will do, one dressing a week, and the owner will be taught how to do 2 dressings midweek, and they will use the hippie scrub in order to try and get that wound really clean, cause they're very scared of infection.

When actually, granulation tissue has such a low infection rate, it's so, it's already, the most viable tissue that you can get. It's already naturally antimicrobial, because it's got such a good blood supply. You do more damage than good if you start to use, things like chlorhexidine or even dilute versions of it on these wounds.

Saline to clean these wounds is absolutely fine. And leaving dressings in place for as long as possible to preserve maximum cell regrowth, is ideal. So you'll see these types of dressings with these permeable membranes that, like the foam dressings, they are designed to absorb, exudate, maintain some moisture, but also so that they can stay in place for maybe 4 to 5 days at a time, really depending on, on, how well that patient is, is, is how easy they are to manage.

So yes, so here's your fibroblast, your myofibroblast. They will pull the edges of that wound together, and they won't start doing that until your your granulation tissue starts to meet that nice epithelial margin. This picture's courtesy of Alistair Hoxtonmore, who's a very kind supporter, and he is showing us here that we've got a lovely epithelial margin here, and this will start to shrink rapidly.

We have some enemies, that are inherent in wound management that can stop this process, that are not, dressing related, but things like movement, interference, licking of the wound, these will also inhibit or damage this fibroblast activity. Movement itself is a cracker because what it does is it will actually disrupt the scaffolding that is trying to support this granulation tissue. And if you, keep disrupting the scaffolding, the body switches into the remodelling phase, so the wound then goes back into inflammation.

It tries to break down the dead stuff. So you go backwards, you get a little bit more exudate. The wound doesn't look too bad, but you might just see a bit more exudate on the dressing.

And then maybe you'll put a new bandage on. It might be immobilised for a little while, it improves a little bit, and then more movement happens and it starts to go backwards again. So, it's like a seesaw.

It's like a balancing act of remodelling versus, rebuilding of this, collagen matrix by the fibroblasts and that being allowed to support that granulation tissue. So if you've ever seen over a hock you might see a pressure, what you think is a pressure sore, and you see what looks like a doughnut of granulation tissue with a little bit in the middle, a bit like this one here. That bit in the middle is kind of your indicator that that bit of the middle of the wound.

Hasn't got a good scaffolding for whatever reason. So it may be pressure, it may be ischemia. It's usually, if it's a doughnut shape, it's usually a movement around it.

You could see a cleft in some wounds where you see sort of a kind of a line, and this line is almost always where you have the two edges of the granulation bed that are almost sliding across each other. Until you immobilised, these things don't necessarily, progress so well. You may even get over granulation because the two edges just cannot adhere.

So there's usually a really good reason why these wounds don't progress. If it's a healthy granulation bed, definitely not infected and you think that things just aren't progressing, it's well worth considering, what factors they might be. The other thing that is worth pointing out at this point here as well is that the fibroblasts and myofibroblasts, their work is pretty much done by 4 to 6 weeks after injury.

So, if you have a tumour removal, which may be what this case here was, and you find that it's progressing really nicely for the 1st 2 weeks, you see great wound contraction, everybody's happy, you're abandoning it, and then you start to find that 4 weeks, you've still got a little bit of a deficit, maybe a bit like this one. And you start to see things stall, and they just get stuck. And that is because fibroblasts, they, the way this, process works, it kind of peaks at 4 to 6 weeks, after which, you then have to rely on the epithelial margin to start to migrate towards the middle of the wound.

So once that work is done, after 4 to 6 weeks, you've got a time where you're just gonna have to be patient and wait for those edges to migrate towards the middle. Now it's a very, very loose rule of thumb, but I would say you're looking at 2 millimetres every 10 days for that epithelial margin to migrate. So let's imagine you've got a 5 centimetre wound day one.

If we give that 4 to 6 weeks and it's contracted by 30%, you could then look at that being maybe 3 centimetres diameter, and then we can look at calculating 2 millimetres every 10 days for 3 centimetres. And if I was really clever, I could probably work that out off the top of my head, but I'm not feeling that clever today. But you can do the maths and you can actually start to work out how long these wounds might take.

To heal through second intention, versus potentially doing a graft or, some reconstruction to cover that tissue with healthy hair follicles, which we now know is going to be a more robust, a more naturally antimicrobial and a better, physiological barrier to the outside world than, our, scar tissue may actually be. So I've already said that the chlorhexidine and hibitan, they're not ideal for granulating wounds, and, quite honestly, I think a lot of people use them in different ways, don't always use the right concentration, don't always know which version of hippy scrub or hippie tame to use at which time. So I would just keep it reserved for wounds that are, in the inflammatory phase within the 1st 24 to 48 hours that you think are at high risk of developing, nasty, types of infections.

So we're talking bite wounds, wounds that potentially have pseudomonas, wounds that are going to be potentially problematic due to the nature of the, cause of injury. And to be sure that you get the right concentration of this in the wounds. So I haven't got this in the notes, but, it might be worth mentioning it.

So you can see here you've got hibita at 5% concentrate. Hibita is the only one that you should use in a wound if you're going to wash wounds, and it's the tain should be diluted 1 in 100 to use in wounds and 1 in 10 for the skin. And it's the hippy scrub that is used on intact skin only.

And the recommendation from the manufacturers that that is used neat, to, prep skin, for theatre, and then you use the hippie ta, diluted to 1 in 10 for a pre-theater, prep. So, it's a contentious area. It's something we're looking into at the moment, but I know certainly that, hippie scrub is something that, can be used in wounds, wrongly, the surfactant, the soap in it is very much detrimental to healing, so never use the soapy stuff, in wounds.

And then finally, we've got this proliferation and wound contraction. So wound contraction here you can see in this case, has done a really good job at shrinking the original size of the wound. But the decision when we come to, those three factors, 3 aims of wound management, we're looking at a functional cosmetic repair, relief of pain and distress, and a rapid return to normal use.

So that's where we question in this case, which I think was a heat pad injury. This wound is starting to granulate beautifully. You can see that the tissue is starting to shrink at the edges where the epithelial margin is meeting granulation tissue.

But actually, 12 weeks is quite a long time, so 3 months pretty much to allow that to close by second intention. The query would be if you could close this with an advancement flap or you could use some reconstruction, it probably wouldn't be too difficult to get the tissue to stretch in this case. You may end up with a better functional cosmetic repair for the client, but also, you will get a better scar, less scar tissue formation.

You'll get a, a much, Much less visits, to the practise. It may be perceived as more expensive initially, but actually, the outcome is gonna be much better in the long run. So, tossing up how many, dressing, changes, sort of the potential complications that can occur in between times, things like, is the patient gonna need, special collars to stop interference and the rest.

We can start to work out what are the best options for that patient in terms of, getting those, those aims. The other thing that is worth, I always think is quite interesting too, with the scar tissue. It's not just the sum and the oils that is produced by the hair follicles, but also the melanin.

Melanin, as a product, sorry, melanin, and, the natural defences against, the elements and the sun. So, we recently saw a case of a Maltese dog, that, was actually from Spain, but it was a white dog. It had a very large, A burn on its back.

It healed by second intention, but a lot of scarring, a lot of wound contraction. It wasn't pretty, as an outcome. It potentially could have been reconstructed in places or partially reconstructed.

But the worry was that this dog was going to be running about in Spain in the height of summer, with a large scar on its, on its back, and that this team. You would not have any natural defence against, the sunlights in terms of melanin and the defence against DNA damage. So you have got a vulnerable bit of tissue there if you've got a large area that could be very vulnerable to cell transformation or future sort of tumours.

So, well worth remembering that sometimes surgical reconstruction is, is possibly the better option. So, your maturation, this is where you've got your healed wounds, but your collagen fibres that have been laid down originally, so there's very random fibres of type one collagen. They've been laid down, as fast as possible and as randomly as possible.

So your your initial scar is quite proud, it's quite lumpy. It probably traps in some blood vessels, so it looks quite dark and purply looking. It may be quite rigid and quite raised.

And when you massage it, it kind of feels like it's adhered to the underlying layers. So you feel like, you've got these sort of adhesions, beneath. Funnily enough, a year later, you could massage the same scar, and you find that it's a lot more supple.

It's no longer adhered to the, tissues beneath, and you can actually hardly see it. And this is because the type 1 collagen is replaced with type 3 collagen over a period of about 1 year, and that Scar becomes a lot paler, a lot more elastic, but will only ever be 80% of its original strength. And this is something that's well worth remembering if you've got patients with extensive scarring, or for pads of the pores, for the limbs, for the low limbs, tips of the tail.

These areas, certainly in human healthcare, an old wound is usually your next one in terms of the most vulnerable points that are going to potentially break down if things start to go wrong. In human healthcare, it's very much, or certainly the, the profession I was in, it was very much, advocated to use emollient creams and ointments that will promote elasticity and protect that tissue from, Drying out. And by using these emollients or these, creams, really, they're not expensive creams, the sort of thing that you buy over the, over the, chemist, over the counter at the chemist.

Things like Diprabase. Usually what you'd aim for is something that would be used on a patient who has got high-risk skin, who's got, allergies. So you want hypoallergenic, you want no perfumes, no parabens, nothing in there that's gonna, potentially sensitise the patient.

They're not expensive. You can usually buy a tube of something called a quiz cream for 1 pound 25p for a large tube that will go a long way. And the owners can massage these wounds as soon as they've healed.

So within the first month, of, of healing, and they can carry on massaging these wounds and, applying these emollients in order to promote elasticity and to protect that skin from cracking and drying, which could produce, Entry, for bacteria and, and other things. So I think it's very much underestimated in, in the veterinary field of how beneficial it is to look after these wounds once they've healed, but certainly for the owners that like to have a little something to do, it's better to recommend these kind of non, Toxic creams, these sort of non-sensitizing creams, than it is to get them using something that they may buy over the counter or over the internet that's full of all sorts of things that could potentially, be sensitising. Unfortunately, the the legislation and the regulatory status for products that are used on animals is not really.

Sufficient enough to guarantee that what you buy in a tin or a tube is actually safe to be used on animals. So if it's safe enough for an, an elderly lady who's got very poor blood supply to her feet, chances are it's probably gonna be OK in, in, in animals as well. There's very little other than things like ibuprofen.

You don't want that in it. But really just these very plain creams are, are, are just, just as suitable for dogs and cats as they are for humans. I really, I just thought I'd kind of finished with, some of the, a little bit of a roundup in terms of how wounds progress and that actually, it's a natural process that is very predictable.

It doesn't really matter what type of wound you've got, but this is that abscess, with a necrotic tissue or a dirty, you could consider the same for a dirty, contaminated wound. The management, works with the process of healing in that we aid debridement during the debridement phase or the inflammatory phase. We get rid of that dead stuff.

We can use products to help remove it, and we can help, you can use things like honey to aid with autolytic debridement, or you can use your scalpel, which is probably a lot more effective if the patient is already, anaesthetized. Wounds will then go through that fluffy phase as they go through inflammation. And again, we're looking at reducing that volume of slough so that the granulation tissue will begin sooner than it would do if we've still got lots of inflammatory mediators and lots of proteasers doing their thing and breaking down proteins.

As soon as Those proteases reduced, we're gonna push that wound into granulation. And that, at that point, we know that we're on a winning, on a winning, we're, we're on the winning side, and that wound will then start to progress through granulation, wound contraction, and then on to epithelialization. The key thing is to look at these wounds once they start to granulate, and one of the things we definitely see through the vet wound library is that there's a lot of hesitation around this granulation phase.

So you get a lovely granulating wound, and then it's a case of nobody wants to really make the decision of whether this should be closed or whether this should close by second intention. Don't wait until, it's 4 to 6 weeks old to decide. Chances are if that wound is quite large, that, scar tissue is potentially not going to be as viable as doing reconstruction, or just get some advice on how you might want to close that wound.

So I would tend to say you should aim to get a healthy granulating wound bed by About 1010 to 14 days. If you've got that at 10 to 14 days, then I usually tell the vet nurses that we talk to, it's time to tap your tap your vet on the shoulder and say, Right, now we need to make a decision. What are we gonna do next, how are we gonna get this closed?

Or do you want me to, dress this wound and we continue by second intention. But somebody usually needs to make a decision at that point. And dressing changes, people often ask, you know, how to manage these wounds in terms of, best practise.

It's a bit Jekyll and Hyde, really. I can never remember which is which. I think it's Doctor Jekyll and Mr.

Hyde. So, Mr. Hyde is the, is the beast, and what you want to be doing is be quite aggressive with these wounds initially, get rid of the yellow stuff, as the honey here, I say yellow stuff on yellow wounds to help you get, get rid of the yellow stuff.

And then once it starts to granulate, it's the clear stuff for the clean wounds, so hydrogels, things that Donate moisture that maintain a moist environment and leave those dressings on for as long as you can get away with, but without putting on dressings that are potentially gonna damage, damage the patient further. So you've got to weigh up if the bandage is going to cause more problem over 4 days than the benefit of putting the dressings on. And I think, I've put a list in the notes, really, of some of these things that, cause wounds to fail and cause wounds to become chronic and, longer term.

Really, the one that is at the top of my list usually is movement. I've got a funny picture of this dog here, but we can see here, wounds to the axilla, there's movement, there's tension. what else have we got here?

Repeated trauma. So if the dog keeps on licking, toxicity, so the antimicrobials using chlorhexidine, that sort of thing. But generally, if there's movement, if there's a factor that is delaying healing, the wound will progress back into inflammation.

So, look at your dressings. If you've got goo on your dressings, chances are there's some reason why that is, non-healing. One of the ones we've seen recently, which is, which I found really interesting is, was the case of a cat that had a burn, and the wound was beautifully granulating.

It would probably be the same scenario here with the axilla wound. Everything looking healthy, no inflammation, but taking the dressing off, they were still exudate and a little bit of discharge every time they changed the dressing. It wasn't getting any worse, but it wasn't getting any better either.

And actually, what I think it turned out to be is the dressing was, moving around on the surface of the wound. So if you imagine the back of the cat had a, had a dressing on a foam dressing that wasn't adherent. So as the cat moved, the dressing moved, and that friction over the surface of that granulation bed is enough to disrupt those capillaries and that collagen matrix, enough for it to push that wound into the remodelling or, into the destructive phase.

So, It starts to break down those cells that have been damaged, and you end up producing a little bit of exudate, and then it would have to then go back into the remodelling phase. So even the most subtle movements and the subtle friction across the surface of the wound, we used something that had a silicon backing on it instead, that, adhered better and didn't move so much. And those wounds progressed much better through granulation than they had done before.

So even the subtlest little things can make a big difference. And certainly, if in doubt, get advice. So that's obviously what we're here for with the veteran library.

If you've got a case and you're not sure what to do, we have, specialists who will advise you through cases and help you find your best route to closure. Sometimes you may find that the route to closure is a lot simpler than you thought. And it might even be something that you can do in your clinic, anyway.

So, if you have a wound that's stubborn, if you've got a wound that you look at and you think, Oh, I've seen one of these before, and they, they, they can be a right pain in the neck, ask for help. There's no shame in asking. And sometimes there are some amazing ideas that can come, in the strangest places.

So, just don't ever be afraid to ask. And really this is a little mantra that we tend to teach everybody. But really all we can do to help wounds, it's really quite limited.

We can work with the process of healing. But, the principles are, from my point of view and our point of view, is that we aim for good wound bed preparation. So we're cleaning that wound up, getting Of all the dead stuff removing the bio burden in order to enable it to granulate, at which point we promote optimal healing.

We aim for an early decision on how this wound's gonna close. Are there any inhibitors of healing that are going to stop this progress? Do we need to do anything surgical in order to, overcome those issues and then need to protect the, wounds from interference and any other factors that might delay healing.

So if you approach wounds sort of fairly systematically, chances are you'll see that the physiology is as reliable as clockwork, and you can see that what you're doing is very much rewarded, based on how you support that healing process. So I think that pretty much takes me up to my time. Thank you for listening.

I've got a picture of my sort of, I should say, least favourite, dressing products at the moment, but, some of you may have come across this fish skin that's been used quite, liberally in places. That is really just a a type of dressing that is really a, a collagen rich dressing that is able to help support granulation tissue formation. It's not a graft as such, but it does aid, proliferation of granulation tissue, but it doesn't fix the problem.

So if there's deficit, your bit of fish skin isn't gonna fix the deficit. Sometimes you still need to bring in tissue from elsewhere. So, that's my little soapbox for that one.

So thank you for listening. And I think any questions? We thank you very much, Georgie, for a really interesting talk.

There's no questions come through as yet, so we'll give everyone just a couple of minute, just a little minute and just see if anyone has any questions. Lovely. But yeah, I found that really, really interesting.

I'm in oncology department at my hospital now, so I don't get to see all of these wounds quite so often anymore. And I, I did used to really enjoy, watching them heal up, over time, and. And I think it doesn't take many of them before you start to realise that there's a sys, it's quite systematic.

And I'm one of those people that's always looking for a pattern and everything, you know, I want to, I, I want, I want it to all be predictable. And, and, I think I was so scared of wounds when I, years ago, when I qualified, that I, I used to refer them. I sort of, signed them over to my colleague.

So, I see the first wound, and then I say, to get it off my hands as quick as possible. So. Yeah.

Yeah. They're absolutely incredible, what, what the body can actually do with, with a little bit of assistance. And, yeah, some of the wounds I've seen have been incredible.

And, yeah, they've healed up absolutely beautifully. And it, it just amazes me. It really does.

It is an amazing process. So I, I just think, definitely, always take a pinch of salt with some of the stuff that you, I'd never believe anyone who says that a product will heal a wound. It's never a product that heals the wound.

It's the body that does it, so does it all. Absolutely. Well, there's no questions have come through, Georgie.

So I think you've, I think everything you've gone through tonight is absolutely clear. 01 has just snuck through. So.

So it, it's, I think it's a comment or a question, it said the presentation was so clear and informative, which I agree with too, that most of her, most of the questions were answered answered in the process, and that like she doesn't trust the use of a lot of antibiotics for wounds but would be quite liberal with the non-steroidals. So yeah, that was one comment, and we close that one down. So actually another question, Lisa says that she finds that when using manuka honey on conscious dressing changes.

Really stings and patients really resist. What are your experiences? So in human healthcare, I think they said the, the statement they say is that about 10% of patients said, say that it is, is quite unpleasant.

So it's very osmotic. It's got a very low pH of about 3.4.

So I would expect it to sting on some wounds. Now, if you do. Find that some of the patients will gnaw at the bandage or they will find it a little bit uncomfortable.

You can dilute it 50% with, a hydrogel, and that will bring the pH up and make it more tolerable, and it won't inhibit the manuka effect or the honey effect. So you can do dilute it 50/50 if you really want to use it in a patient that finds it a little bit sensitive. And it will still, still be beneficial, but definitely stop the honey once you get to a granulating wound, you don't need it once you get to that point.

OK, thank you. And then there's another question, what is the opinion about non-steroidals for chronic wounds? Yeah.

So, I do believe there are some papers out there that suggest different methods to, to reduce inflammation, and reduce. It depends what you're treating, to be fair. So, I, I don't think it's quite as significant as in humans, where we've got, people who've got chronic arthritis, and they'll have, other comorbidities that mean that You have to almost stop the steroids, to allow the wounds to, start to heal.

So you kind of have to play one off against the other. But I do believe there's some opiates and, of the like who that are less, influential on the inflammatory phase of healing. So, certainly case by case on that, on that one.

But I think, certainly if the wound is chronic. just don't know why you would be using the inflam anti-inflammatories if the wound was chronic without finding out why the wound was chronic, if you see what I mean. Does that make sense?

I think I, I think so, yes. We've got a, we've got a list of 12 factors of healing delay. So what we would tend to do is go through that 12 factors of healing delay, so movement, interference, disease, comorbidities, all of those sorts of things.

As you go through that list, you kind of tick off yes, no, or maybe. There's not a lot of those things on that list that are, would, indicate using steroids, if you see what I mean. It would only be if you, if you're using it for something else at the same time, you'd have to weigh up which is more important.

Absolutely. Yeah. So, one more about the, what do you think of the vein flush?

Vetricin flush is a high. Chlorous acids. It's quite a well-known technology.

It's been used in human healthcare for quite some time. It's quite safe, for use on, wounds, I believe. There's quite a few different versions of it now.

I could make myself really unpopular and say that even Morrison's Supermarket have got their own version at 1 pound 89 pence if you care to go and have a look. So it pretty much is everywhere. It is, quite a a useful antimicrobial.

I'll use my toilet story, but I usually say you could spray your, antiseptic at the toilet all day every day. But if you're not going to get rid of the turd in the bottom, you still have to flush it first. Does that make sense?

I know that's horrible flush it with water first, and then if you want to decontaminate afterwards, you can use your Beresin. That's, it's not a bad product, but it's not a substitute for flushing. Absolutely.

So what, one more. So have you ever used the allure spray or a silver spray? So there's some individuals at the practise that have used this lots at end stage wound heal.

I love the wording. I can see right through it. And I wish I could stop people using it as well.

I can. The people I've seen use it, use it on horses a lot because they can spray it. It covers it and stops the flies getting to the.

Right, OK. From a practical point of view, yes, I've seen someone also use it to make a fake Christmas tree with, theatre gloves and they look beautiful, but yeah, it's I don't rate it at all. I'm sorry.

That was, I think, pretty much the same opinion for the lady who'd asked the question. So, and then one more comment, this was from Michael saying, having been qualified for 40 years, I've And lots of wound management, both dressing and surgical, but you have still given me some useful tips and hints, and it was a great webinar. So that was a lovely comment to finish on.

Thank you very much, Michael. Thank you very much. So yeah, that's coming, come to the end of our webinar.

So thank you very, very much, Georgie, for a really, really interesting talk. So, and thank you very much to everyone else who's joined us this evening. I hope you all have a wonderful evening.