Good evening everybody, and welcome to another Thursday night members webinar. My name is Bruce Stevenson and I have the honour and privilege of chairing tonight's webinar. I don't think we have any new members tonight, so not much housekeeping.
You know how it goes. Click on that Q&A box, pop your questions in there, and we will keep those over to the end. Just a heads up, we have got poll questions, so, Pay attention and don't be shy when we get to the poll question.
It is absolutely anonymous and Sarah really wants to hear what you have to say in that poll. So tonight's speaker is Doctor Sarah Kaney, and she is the chief executive and founder of VET Professionals Limited based in Edinburgh in the UK. Sarah has worked as a feline-only vet since 1994.
She's a University of Bristol graduate and also completed her feline medicine residency and PhD studying feline immunodeficiency virus infections at the same institution. Sarah spent 4 years as a lecturer in feline medicine before leaving to pursue a career in private practise. She has always enjoyed seeing a mixture of first opinion and referral feline medicine patients and has a particular interest in elderly cat medicine.
Sarah is internationally recognised as one of only 13 veterinary specialists in feline medicine working in the UK. Sarah founded Vet Professionals in 2009 and has authored and co-authored a number of vet professionals caring for a cat series of books. She regularly conducts online questionnaire studies with cat owners and has published widely in prestigious international journals.
She has been an invited speaker to veterinary conferences around the world. Sarah has worked for many years in the UK cat charity, the International Cat Care, and the International Society of Feline Medicine and is proud to support the work that they do to improve the standards of cat care. For those of you that haven't heard Sarah before, you are in for an absolute treat.
Sarah, welcome back to the webinar vet and it's over to you. Thank you so much, and it's lovely to be here with you this evening. I'm I'm slightly frustrated that I can't show my face, and I can't see your faces either.
But thank you to all of those, people who are joining me tonight. It's, it's lovely to be with you. And it's also great for me to be talking about a topic which I care very passionately about, which is hypertension in cats.
And I hope that I'm going to be able to present some useful tips to you on some of the challenges that we face when we try and diagnose and manage this condition, which is pretty common condition, particularly in that elderly cat. As has been mentioned, I have got a business called Vet Professionals, and Vet Professionals website has a lot of useful free to access resources, including also some little webinars, which I will mention, and indeed, fact on this first slide, one of the sections of webinars in the video tutorials page, which is under the Helpful info menu is the 10 minute tips, selection of webinars for vets, and some of these actually are on blood pressure, but there are other topics as well. So please do visit my website and have a look around and help yourself to those resources, and some of those resources are aimed at your clients as well.
I hope you'll find those helpful. Another very useful website to mention at the very beginning as well is actually Siva have a website called ease the pressures.co.uk, this one at the top here, and that has also got an awful lot of free to access resources, including a series of webinars that I did last year for half hour webinars, so a total of 2 hours on hypertension.
It is a big topic. So if you feel like I haven't completely satisfied your, your sort of thirst for knowledge, then I can recommend that as a resource. And they also have other webinars that are free to access on their, site, by many other really excellent speakers as well.
So there, there's a lot out there, and a lot that can help complement what I'm gonna say this evening. So what I'm going to talk about in the next about 45 minutes, I can keep to that some time, is what we mean by this term systemic hypertension. What precisely is the definition of that, what causes it, how we can diagnose it, how do we assess blood pressure and how do we confirm that diagnosis?
And of course, very importantly, how do we treat this condition. So, systemic hypertension, we all know that means high blood pressure in the systemic circulation. But the current definition is very specifically that for cats, systemic hypertension means that their blood pressure has been persistently.
160 millimetres of mercury or greater. That's the systolic blood pressure reading has been 160 millimetres of mercury or greater. And that indeed, this is a persistent pathological increase in their systolic blood pressure.
And we know that hypertension is pretty common in cats, and it probably overall affects 20 to 30% of our senior and super senior cats. That's cats aged 11 years and over. And that's been shown in a number of publications over the years, and indeed that there is a very definite age associated risk of hypertension, as in the older the cat, the higher the risk of hypertension is.
And so the data I've included. Included in this box at the bottom of the slide is actually from the paper that I have a screenshot of on the slide, which is a vet Compass study, where about 350,000 cats visiting UK vet clinics were assessed, and they looked at the proportion of those cats receiving blood pressure assessment. It was not all 350,000 cats, as you won't be surprised to hear, but they looked at the cats that had had their blood pressure assessed, and then where hypertension was diagnosed, they also reported the age of the cats and they're presenting signs.
And you can see that, in their study, about 10% of the cats aged 9 to 13.5 years old were diagnosed with systemic hypertension, whereas 60% of the cats aged 22.5 years and over where blood pressure is measured, had that diagnosis.
So there's this very strong age associated risk of developing hypertension. And the last point, really, just to introduce this topic, is that of course hypertension is quite common in people. So, probably a number of people that are listening tonight will have some direct experience of this either in themselves or in family members or friends.
It is something that's quite common and therefore something that our clients have a degree of familiarity with as a possibility. Some important definitions, beyond that would include, firstly, a really important one, which is situational hypertension. This is a relatively new term.
We used to refer to the white coat effect or white coat hypertension, and this is where we have a cat that has a transient increase in their blood pressure associated with anxiety or excitement, as a consequence of that stress, visiting the vet clinic, for example. And in most cats, that's the impact of stress is to increase the blood pressure, hence the term situational hypertension, and often that's by less than 30 millimetres of mercury, but can be and certainly has been reported in some studies to be as high as 75 millimetres of mercury, which is just massive. You your cat's blood pressure essentially can't remain.
Within the reference range, if you add 75 millimetres of mercury on top, that is definitely going to be a high reading. But also important to mention that actually we can have hypotension, as a consequence of stress. It's much less common, but of course, it can be seen and in some cats that might mask true hypertension.
So, It's just a starting point to to really underline the fact that unfortunately, blood pressure assessment is not as black and white as we would like. A key message, of course, with situational hypertension is this doesn't need treatment. It's not a true pathological, persistent increase in blood pressure, but it causes us problems because if we have a higher reading, we then worry, well, has this cat got genuine hypertension that needs treatment?
Or is it one of these stress cat situations? So we're gonna talk a lot later on about how we go about trying to answer that question, because it does commonly arise. Another important definition would be idiopathic hypertension.
So this is a persistent pathological increase in blood pressure where the cause of it is not known. And this is sometimes referred to as primary hypertension or essential hypertension. And it's something that we don't know very much about in in the cat world at the moment.
We think It is responsible for less than 20% of our cases of systemic hypertension, so the minority of cases, and certainly it is thought that it's quite likely that some cats in this category actually will have early renal disease, but it's just difficult for me, for us to make that diagnosis. The majority of cats that we diagnosed with systemic hypertension have secondary hypertension. This is a persistent pathological increase in blood pressure related to another disease or a condition or a medication, that has caused that situation.
And that's thought to account for more than 80% of our cats with systemic hypertension. So if we ask the question, which cats are vulnerable to developing systemic hypertension, we can see that the idiopathic causes is the the minority, less than 20%. Secondary is more than 80%.
And if we look at that in a little bit more detail, the most common cause of systemic hypertension is chronic kidney disease, where it's currently estimated that between 20 and 65% of cats with chronic kidney disease develop high blood pressure. The relationship between hyperthyroidism and hypertension is still a topic of some debate, and we don't actually know whether hyperthyroidism causes hypertension or whether perhaps both of these conditions are common in the same age group of cats. So, the prevalence of of hyperthyroidism in the general old cat population is about.
10% of cats. The prevalence of hypertension in old cats is 10 to 20%, and funnily enough, as you can see here, 10 to 20% of cats with hyperthyroidism are currently reported to have high blood pressure. So, as I said, it's not necessarily a cause and effect.
It may just be that these two conditions are common in the same sort of age range of cats. Primary hyper aldosterinism or KOhn's disease and adrenal tumour overproducing the hormone aldosterone, treatment with erythrocyte stimulating agents such as erythropoietin and arbutin are also acknowledged causes of high blood pressure. And then there are other conditions where either they're Very rare things like fair chromocytomas and Cushing's disease in cats, where there is thought to be a link between those and hypertension, diabetes and obesity in other species.
There is a relationship between them and and high blood pressure, but that has not been conclusively demonstrated in cats yet. But as has already been emphasised, this is very much a condition which is common in older cats, and the older the cat is, the greater the risk of hypertension developing. So how do we identify these cases?
Well, it might start by thinking, well, what sort of clinical clues might tell us that this is a possibility? And in our cats with systemic hypertension, I think we can subdivide those clinical clues into those clinical signs that may be seen as a consequence. Of the hypertension, so that the damage caused by the hypertension.
And secondly, in those cases where we have a secondary hypertension, we may have clinical signs related to that underlying disease, for example, the cat with chronic kidney disease, is losing weight, perhaps has a reduced appetite, is is drinking more. When we look at the the damaging consequences of hypertension in the body, we talk about 4 target organs that are particularly vulnerable to the damaging consequences of high blood pressure. And those target organs are the eyes, the central nervous system, the heart and the cardiovascular system, and the kidneys.
And these organs are particularly vulnerable to to damage because of the way that their blood flow works and the the sort of damage or how that might be manifested in our cat would include, for example, in the eyes, bleeding or edoema, leading to perhaps retinal detachments, and from the cat's perspective, visual deficits and blindness. From a CNS perspective, a whole range of possibilities, very small bleeds might cause some behavioural changes. Common ones would be vocalising more, particularly the cat was vocalising more at night, signs of dementia.
And of course, we do need to consider other possibilities in terms of causing those signs, but hypertension is one of them. More severe manifestations might be a cat that looks like it's had a stroke, so it looks like it's had a big bleed and it's in a coma or having seizures. And then from a cardiac perspective, developing a new heart murmur or a gallop, due to that cardiac remodelling as a consequence of hypertension would be something that should perhaps raise our suspicion in our patients.
And from a renal perspective, we can see proteinuria, which is typically quite mild, so urine protein to creatinine ratio of perhaps 0.4 to 0.6 would be quite typical, but also the the hypertension can cause damage that contributes to progression of clinical signs from a renal perspective.
So quite a range of things to look out for. And of course, often in the very early stages of disease, you won't get any of these clinical signs, hence this term of hypertension being a silent killer. It needs to be quite advanced before it actually makes itself obvious.
And we want to, of course, capture these cases before they get to that point. If we look at that vet Compass study that I referred to in an earlier slide, and see, well, how did these cats present, you can see that actually the majority of the cats presented with clinical signs related to the hypertension, often ocular clinical signs, so retinopathy and blindness in, certainly a high proportion of the cats. But about a third of the cats were detected because of monitoring of concurrent disease, for example, cats with kidney disease that are having routine blood pressure checks, which is great.
Just 4% picked up with what they called the geriatric health check. I don't like the word geriatric because it always sounds a bit fully a party. So the senior and super senior, terminology that international cat care, I think is, is a nicer one.
But in essence, As you can see already, there's now an opportunity for us to actually do a bit of a better job because we don't really want to just be diagnosing these cases when they present with blindness. We want to get in there at the senior health checks and the monitoring of concurrent diseases to find these cats at an earlier stage. So, in summary, when should we assess blood pressure in our patients?
Well, definitely in those patients that have clear evidence or suspicion of target organ damage. So those cats coming in with visual deficits or, ocular haemorrhage that are compatible with a diagnosis of hypertension. Definitely, if we've done a urine urinalysis and we find proteinuria, this should be on our list of possible causes.
Definitely, if we find, our cat, our older cat has a new Heart murmur or gallop rhythm, high blood pressure should be considered. There of course other differentials, things like hyperthyroidism, but certainly hypertension is is one we should consider. Also, if we are doing our echocardiography and we see left ventricular hypertrophy, we should check blood pressure, not assume that this is just a primary cardiac disease, again, particularly it's an older cats.
And lastly, the cats that has behavioural or neurological signs that we should consider hypertension as a possibility. I also would like you to wear it all possible, screen those cats that are at a greater risk of developing hypertension. So this is cats that we know have diseases that have had a reported association with high blood pressure, whether that's kidney disease, thyroid disease.
Primary hyperinism, cats on Dre eating, for example, for anaemia, but also those, if we can, those middle aged and older cats, and, and I'll share with you in the next slide the ICA cares well cat guidelines for . Routine health care of of cats according to their life stage, what's recommended, and they recommend blood pressure assessment starts, if possible, in seven year olds, cats and upwards. And I also would encourage you with your pre-anesthetic health checks of older cats to not just do blood tests, which of course can be very helpful, but consider blood pressure assessment pre-op as well.
ICA care's guidelines for life stage appropriate screening are available in summary here, but also in more detail, I'll refer you to their website as written on this slide, cat care number 4life.org. And these outline, according to the cat's life stage, what is suggested for healthy cats.
So this is cats that are coming in for their their sort of health assessment, not because There's any sign of illness, but just as part of a routine preventative health care. And the recommendation as far as blood pressure assessment is that where possible, once the cat reaches the age of 7, it is considered that blood pressure should be included where possible. Initially once a year in the 7 to 10 year old cats, but once the cat reaches the age of 11, then where possible, we'll certainly consider doing a blood pressure check twice a year if you can.
So how do we assess blood pressure? How do we diagnose hypertension? Well, measuring blood pressure is obviously an important part of that, and we use indirect methods when we don't stick a needle into an artery.
The cats will be very glad to hear. We use these indirect methods such as the Doppler that's being shown. On this slide on the left, but also we can, very importantly assess the target organ damage, and that helps to determine whether or not that high blood pressure reading is associated with genuine hypertension or whether it's perhaps one of these situational hypertension cases.
So at this point, I have a poll question that I would like you to answer, if at all possible, which really just is to tell me a little bit about, for those of you that are tuned in, what type of of monitor that you usually use when assessing blood pressure in your conscious cats. So do you usually a Doppler or in a symmetric, or you use a machine and you just actually don't know what sort of machine it is, or you don't have a blood pressure monitor, or perhaps, and I do want you to be honest, you have a monitor, but actually, you're not really doing blood pressure assessment very often, or perhaps not at all at the moment. It'd be really helpful for me to see what, which of these is closest to, your current situation in your clinics.
Folks, the poll is open. Simply click on the answer that best suits your situation. As Sarah very kindly typed at the top, be honest, it is anonymous.
There's no right or wrong answers. This is just The truth of what happens and it's great feedback for Sarah as well. As you've heard, Sarah is very, very involved with cats and part of what she does is to gather information on how we vets are looking after our feline patients.
So this would be a great way to give us some feedback. So, just, I'll give you another 5 seconds before we close that poll. And Sarah, let me show you quickly those results.
There you go. OK, lovely. Thank you very much.
So we thank you very much to all of you that, that have, have voted here. So we've got the most common answer is the Doppler machine. But as a smaller proportion of you are using a symmetric machine, and you all know what you're using, so that's great, and you are all using something if you have it.
But we do have a small number of people that don't currently have a blood pressure monitor. So thank you very much for sharing that information with me. So the next topic really I'd like to tackle is, what sort of blood pressure monitor would I like you to be using, I guess, might be the question.
And for most of you, I think, do know that there are broadly these two options for our conscious cats. The Doppler, which is, one example is on the left hand side of this slide, involves using a probe, and you put the probe onto the skin and you listen to. In the artery, and then you have separate to that probe.
You have a cuff that you place on the the limb or the tail, the same area of the body that you're listening to that pulse, and that cuff is attached to a pressure gauge a spig momentometer. There's lots of really unpleasant words to say in this presentation. And you then can, once you've listened to your your pulse, you can inflate your cuff, and you can look at this big to tell you, what your systolic blood pressure and diastolic blood pressure sometimes are in that particular patient, and it's a very manual technique, whereas the symmetric option, there are a variety of machines, one shown on the right hand side here, and the differentiating factor for these machines is that they're very clever.
Everything is is sort of a bit hidden and a bit mysterious, but they have this cuff, a very special cuff that has sensors within it. And the sensors within the cuff can detect pressure wave oscillations, hence the name symmetric, in that artery wall. And you press a button and the cuff inflates and it deflates, and the sensor within the cuff collects lots and lots of measurements and then can give you a systolic blood pressure, a diastolic blood pressure, often a mean blood pressure and a heart rate.
So you get a lot more numbers out of your oscillometric machine. But it is completely sort of, I say, sort of invisible technology. Whereas the do tend to really mainly just get your systolic blood pressure reading.
So which of these machines do I think you should get? Well, the, the simple answer actually is to really make you clear that none of these machines are perfect. So whatever I say, just remember, I am saying it from a Perspective of neither of them are perfect.
They are both indirect, they are giving you an idea of blood pressure, but they are certainly not to our current published knowledge, as accurate, sadly as sticking a needle into an artery. My preference of the two is the Doppler methodology, the first one that I mentioned, where you have this separate probe and listening to flow of the artery, and doing everything very manually. And that's partly based on my experience.
It's a technique I'm very familiar with, and partly based on publications which have tended to say that the Doppler is more reliable for conscious cats. For those of you that would like any more references on this topic, then I can share those. With you, and you're you're welcome.
You can send an email actually through the contact button of my website, vetprofessionals.com, and I can share you some slides with some summary data on and what you'll see is basically there are pros and cons. Some studies show good, some studies show bad.
And overall, the main thing is neither of these methodologies are perfect. But consensus among among specialists at the moment, it would be that the Doppler is is probably the preference of the feline specialist. So what other tips can I give you?
And many of these tips actually applied to both methodologies. So the first tip is to remember to be cat friendly because we want to minimise this situational hypertension. So that is, it should be our focus to have everything as calm and serene as possible and minimum restraint, in, if permitted, and obviously we're in strange.
Times at the moment with COVID, having the owner present with the cats can be helpful in terms of many cats' stress levels. So that is something to consider. I do think as well that the the COVID consult where the cat has been handed over in the car park and has not been in a waiting room, actually can be good for blood pressure because often I think the Waiting room experience is quite stressful for our feline patients.
And just being as calm and quiet, having a period of time to to allow the cat to get used to the environment, what we call this acclimatisation period, so 5 or 10 minutes in the consult room where the cat can just sort of catch their breath and relax a little bit. And certainly if you're doing a Doppler methodology, I think wearing headphones is helpful, so that the cat can't hear all the noise associated with that technique, which can be a bit off-putting. Second tip is to use an appropriate size cuff, by which I mean the width of the cuff, and the ideal width of the cuff should be 30 to 40% of the limb circumference or the tail circumference if you're using the tail.
If you use a cuff that is too wide, you will get a slightly lower reading, and that will be less accurate. So bear that in mind if you are forced to use the wrong cuff for whatever reason. I really like these Hawkinson cuffs as shown on here.
They're very soft and flexible. They inflate along their entire length, and they have really, really good, Velcro. So they stick, they don't pop off.
So if you have cuff frustration, which I have certainly experienced in many, many, times in the past, you might want to invest in these. They are expensive, but I think they are, are worth it. Next tip is the cuff position, so the cuff should be level with the heart.
Again, if it's not, that will impact on reading. So if the cuff is below the heart, as per the Siamese on the left, you'll get a higher blood pressure reading. So try and have the cuff level with the heart as far as possible.
From a Doppler perspective, I've mentioned headphones. Another tip would be, you can never have too much gel. It does get a little bit of a messy procedure, but if you're struggling to have here a clear pulse signal, then just, turn the machine off, put on some more gel, and usually it will just magically appear for you.
Also, bear in mind you can press very hard and actually occlude the artery through pressing too hard, so remember to be gentle. From an asymmetric perspective, the main tip would be, to, if you can view the graph that the machine is using to generate its data. So you can see it's a nice sort of bell curve and not a big scratchy mess where the cat perhaps fidgeted and and the machine was perhaps distracted, shall we say, by muscle movement in the leg or the tail, and that's going to perhaps give you some erroneous readings.
On my website and the video tutorial section, you'll see some videos on various techniques, and this is one that Dec kindly did for me. And on the website, it's narrated fully, this video. So I took away most of the sound for for playing to you this evening.
This is, sadly no longer alive, but previous cat of mine, who's not very happy about blood pressure assessments. He'd had some gabapentin pre-visit. To sort of calm his nerves, if you like, but he's still expressing some disgruntlement with the procedure.
But you can see, working through, putting the cuff on below the elbow, plenty of gel over that common digital artery. And then once I press the button on the blood pressure machine, you'll be able to hear, hopefully through your system to the pulse signal, that, that we've got with his reading and watch me collect a reading. Oh.
So inflate the cuff nice and gently as well, just to make sure you can still hear it, the cat's not put off. Go a little bit higher than the point where you cut it off, and then very slowly start to deflate. Hopefully all had the return of the pulse around about 140, so that is the systolic blood pressure.
I've actually deflated a bit faster than I should. But hopefully you can hear there is a sort of change in tone in the blood pressure, the, the audible noise rather, it changes from that sort of shorter when the systolic reading is collected to that more noise that you hear, pre-inflation, and that's the point where it changes is, is, around about the diastolic blood pressure reading, although that's something we don't, routinely collect, we focus on the systolic reading. Take multiple readings.
If the first reading is very different, discard that, deflate the cuff, completely in between readings, otherwise, the poor cat's leg can get quite uncomfortable. Collect, several readings and calculate a mean. You're aiming really for a nice plateau of readings that they're all very similar, but in some cats that are anxious, we never quite get that.
So in that situation. Lowest reading I've got is the one I would think is most representative. And then, of course, keep good records.
So record not only the cuff size, but also the location and the readings and see have lots of resources designed for recording this sort of information, which are probably available in a downloadable form, but I know I've also seen pads that you can tear off sheets and use to collect your readings. In terms of interpretation of results, systolic blood pressure, normal cat in a clinic situation, would hopefully have a blood pressure between 120 and 140 if you've got a nice cat friendly clinic. Many cats have a systolic reading between 140 and 159, and quite a few of those cats will be normal cats that have this situational hypertension, so a slight increase in their blood pressure.
Some of them, however, will be perhaps pre-hypertensive. They're not quite clinically hypertensive, but they're they're on the way. So these are cats that we definitely want to have a close look at for target organ damage, and we want to monitor closely to to make sure that we're on top of things and pick up that over hypertension, should the cat go on to develop it.
And then we have those cats that have blood pressure readings of 160 or greater, which we tend to divide it into the hypertension and the severe hypertension. So the hypertension is, is systolic blood pressure 160 to 179 versus severe hypertension where blood pressure is 180 millimetres of mercury or greater. And the risk of target organ damage is accordingly greater in those cats with severe hypertension.
But of course, we do need to also remember that actually the cats with readings in these, both of these category categories could have situational hypertension. Remember that I said earlier on that some cats, that the stress increase in blood pressure can be 75 millimetres of mercury. And if you add 75 millimetres of We're onto a cat whose normal blood pressure is, let's say 130, then that's over 200 millimetres of mercury.
So this leads us into the really important topic of, well, how do we treat these cases, as in, how do we distinguish between those cats that have genuine hypertension, which needs treatment versus those that have situational hypertension and do not need treatment. What is a sensible approach? Well, the approach that I take, is firstly to make sure that I have collected my readings in as calm and cat friendly an environment as possible, and that I have included this acclimatisation period, ideally 5 to 10 minutes before readings are collected.
So that's the first thing to do. And then the next thing to do is to look for target organ damage by assessing the eyes. And I'm gonna talk through that technique next, but I do think it is an incredibly helpful way of identifying abnormalities that can help you to confirm genuine hypertension.
If you find that there is ocular target organ damage and you have a high reading, then you have confirmed your diagnosis of systemic hypertension. If on the other hand, you look at the eyes and there is no target organ damage, and you've just got one high blood pressure reading, then my advice and and the recommendations from ACVIM are that we should confirm persistence of that high reading before considering treatment. And what they recommend is that if blood pressure is between 160 and 179, that hypertension category, that we monitor our, our patients ideally over two or three occasions over a 1 to 2 month period to try and decide is this cat stressed or has it genuinely got high blood pressure.
With those cats that have a severe hypertension reading, so a reading of 180 millimetres make or higher, because the risk of target organ damage is so much higher, it's suggested that we collect those several readings over a shorter period, 1 to 2 weeks. We can also concurrently look for evidence of systemic diseases that might be causing that high blood pressure, such as chronic kidney disease, and we can, if we want to also look for other evidence of target organ damage. So damage to other organs, for example, look at a urinalysis for evidence of proteinuria.
But the eye examination I do find incredibly helpful. And, again, the key thing is really that if we do see target organ damage, and we've already got a high reading, then we can confirm that that cat is hypertensive and move on to treatment. Whereas, if we have no evidence of target organ damage, we do need to confirm persistence of those high blood pressure readings.
So the technique that I recommend, and I'm not an ophthalmologist, so apologies to any ophthalmologists that happen to be listening to this webinar, would be, the, the technique I prefer would be this distant indirect ophthalmoscopy. And the equipment that you need for that is a light source and a lens. And there, as always, there are a number of options for this.
If you are an ophthalmologist or or that way inclined, or if you're feeling very, very well funded, you can spend quite a lot of money. So for example, the bulk pan retinal lens is a good lens. I've got one of these, and they cost about 200.
Pounds. So they are a lot of money, but they are lovely. And you can also get a focus light source, this spinoff attachment shown in the right hand picture, which is what an ophthalmologist would, I think, prefer to use.
Certainly, that's what I was advised to get when I started looking at cat's eyes all those years ago. But of course, many clinicians will probably think, well, I haven't got, you know, maybe 400 pounds to get this sort of kid. I just can't do that.
And if you're in that situation, then definitely don't despair because you can get some really very inexpensive acrylic lenses. And I've shown a screenshot of one example here with the price, 42 pounds plus that for this 20 diopter condensing lens, and you can use that as your lens and then as your light source, you can use your normal direct ophthalm direct ophthalmoscope. So, another word that is a nightmare to say.
And if you just set that to a circle, you've now got a dimmable light source. And the and the fact that you can dim it is really, really important for examining cat's eyes. I would really say, as written on the slide, avoid a pen torch because most pen torches, you can't control the light intensity.
It is sort of dazzlingly bright, and that's painful for a cat. So you can get one of these 42 pounds and lenses, and that's essentially you will have The other equipment already in the clinic, and the only other consideration is you need a dark room. If you don't have a dark room, you might need to put drops in the cat's eyes to examine them.
And whilst that's perfectly fine, it takes time for the pupils to dilate. It complicates your day much better if you have a dark room. So if you have blackout blinds over the windows, you can do this procedure in less than a couple of minutes.
It really is very quick and very simple and very short learning curve as well. So in your completely dark room, but obviously, the photos would be completely unhelpful. You stand arm's length from the cat, and so I have my left arm straight, and I have the light source by the side of my head, and I shine the light source towards the cat's eye, and I adjust the angle, you know, sort of up, down, side to side, until I get that really nice to people with.
The cat's eyes on the road. And once I've got that to people reflection, I then insert my hand lens in front of the cat's side, just in front of it as shown on that right hand picture. And you will also find that if you get one of these lenses that one side tends to be more bulgy than the other.
And if that is the case, then the bulgy side should be facing you, belly to belly. And what you will see if you have one of these lenses, is a large portion of the funder. So really, almost all of the funders in one view, and often it's really obvious to see whether or not there are issues to worry about.
So that is the big advantage of doing this. And that Very much compares favourably to using a direct orphthalmoscope in the situation where with your direct almoscope, of course, your light sources right by the cat's eye. The pupils tend to constrict, so we just see a tiny bit of the the back of the eye, and we can't really more broadly examine the fundus.
And happily as well, for us, with again, apologies to any ophthalmologists that are listening, is that most healthy cats' eyes, actually look very similar. There are very few breed variations in what the back of a cat's eye looks like, and I think that is in contrast to dogs from what I've been told, certainly. And mostly they have this sort of greeny yellow background to the eye and you can see the optic disc, this sort of white circle and the vessels over the fundus there.
In subalbanautic cats, cats are breeds like the Siamese and the rag doll that have these colour points temperature sensitive coat changes. Many of these cats will not have a pigment layer at the back of their eye, and that can be confusing because you will see See, as well as your retinal blood vessels, you will also see lots of choroidal vessels underneath that pigment layer. And so everything looks very stripy, red and quite a shock when you first examine a Siamese's cat's eyes.
So that is the one exception to my generalisation, that most healthy cat's eyes look the same. Just make sure you do look at some Siamese and rag dolls before, perhaps wanting to to do so in a cat that's at risk of hypertension. And from what's been published, we know that ocular target organ damage is very common.
So, studies have suggested that up to 80% of cats with hypertension have ocular target organ damage. So it's a good way, I think, to help us screen for high blood pressure. And those of you that don't have a blood pressure monitor, you can do your eye examination, and I promise you it will be helpful.
So what might you see? Well, you might see changes within the retina, so hypertensive retinopathy, which might include changes to the blood vessels, the vessels being more tortuous, varying in diameter. Hopefully that is evident in perhaps the picture on the right, I think, hopefully outlining the arrow now, this vessel, for example, you can see, it does seem to vary in diameter.
This is possibly even an aneurysm on that vessel down at the bottom. And that's because the, there will be some basics of constriction of these arterials to try and protect the capillary bed from that very high pressure blood. But over a prolonged period of time, the artery walls get get weakened by the hypertension and start to bulge in places.
So you get this sort of varying diameter of the vessels. And the left hand picture, what we can see here are some areas of retinal edoema, these sort of greeny circular areas, and it is quite subtle are areas of retinal edoema, and that would be a very early indication of potential hypertension. In the right hand as example, we have got some haemorrhage as well, the sort of red splotches, which definitely makes life easier.
So those are, these are some of Changes we can see some more dramatic examples here. So on the left hand side, we've got a cat that's got some retinal edoema, again, these sort of greeny circular areas, but also on the right, within this dash line, an area of the retina it's very out of focus, because in fact, that bit of retina has lifted off and it's closer to the camera. So although we can sort of still see blood vessels within it.
Everything is very hazy because of that detachment, and there is some tortuosity of the vessels as well. And then the example on the right is again, very dramatic. We can see haemorrhage, we can see an aneurysm, lots that's out of focus, and also some areas of funders where it looks like there is some retinal degeneration.
It's very hyper reflective in that central portion, indicating perhaps long standing or chronic changes. We can also get changes to the choroidal layer, so, subretinal edoema, retinal detachment, a possibilities there, and this is one of those really heart sinking examples of a patient that comes in with blindness and has these hugely dilated pupils. I have not put any drops in the eye.
And just shining a light into the cat's eye, you can actually see the retina. We should not be able to see the retina and we shine a light in the cat's eye, but in this one, we can, we can see vessels in it as well. And, and therefore, you know, we've got severe bilateral retinal detachment associated with hypertension.
A very much prettier version of that from Professor Sheila Crispin on this slide on the left. So again, you can see that sort of billowing retina floating towards us, and the, the blood vessels that there's for the most part not really obvious haemorrhage, perhaps a little bit up here, but we can see that it's completely detached. And then lastly, we can see changes in the anterior segments, so we can have high femur, bleeding in the front of the eye, and that sometimes can make examination of the back of the eye very difficult.
So I included this example here of where we actually did an ultrasound of the eye, and on ultrasound, and you can put some local anaesthetic onto the eye and then put some ultrasound gel onto the I to actually place your probe there. We have the the globe is this sort of black circle. The optic disc is that very bright white area at the bottom, the fat in the optic disc and nerve shows up bright white, and then to the left we can see this portion of retinal detachment where it's lifted off.
It looks a bit thick. It's probably a bit swollen as well. So in conclusion, Oer examination is fairly straightforward to do.
I think it's quite a steep learning curve. And there are some videos on my website also talking through this technique that you might find helpful. If we have a high reading and ocular target organ damage, we have confirmed our diagnosis and we can move straight to treatment.
But if we just have one high reading and no ocular target organ damage, then situational hypertension is still a possibility. We need to demonstrate persistence of that high reading before we consider treatment. So let's finish now with treating hypertension.
How do we approach that? Well, the key message is really that if we do think that our cat has got systemic hypertension, then they need anti-hypertensives, even if we know they have an illness that may be causing the hypertension, and even if that illness that might be causing the hypertension is treatable. So, for example, a cat with hyperthyroidism, we don't.
We cannot just treat the hyperthyroidism and hopes that the hypertension goes away. Most, if not all, of hyperthyroid cats with hypertension need lifelong treatment with anti-hypertensives, a very small number when you treat the hyperthyroidism, the the high blood pressure will normalise, but it really is a tiny number in my experience. For the most part, these cats seem to need a lifelong therapy, so it should be treated as a separate disease.
There are at the moment, two medications that are licenced for treatment of hypertension in cats in the UK. Amlodipine is the one that probably most people are familiar with, because for years we were using human amlodipine tablets to treat our cats, and then some it started to reformulate them in a more cat appropriate size and then happily Siva actually licenced Amodip a few years ago. And this It is often extremely effective in lowering blood pressure.
It's a peripheral arterial dilator, and it's typically very straightforward, half to 1 tablet per day for the cat, often actually very easily accepted. They're quite palatable tablets. Most cats don't mind having them.
And it is, I think, the first choice for severe hypertension, because it has the most proven impact in lowering blood pressure. The second licence option is Seintra, the hypertension form of of Seintra, which contains Talmisartan and angiotensin receptor blocker, and that works by suppressing the renin angiotensin aldosterone system, which is commonly activated in cats with kidney disease and therefore there is perhaps a particular rationale for using cement. In hypertensive kidney cats, but it is needed a higher dose to treat hypertension than when used just for proteinuria associated with CKD.
So the proteinuria dose is 1 me per kg starting dose, whereas for hypertension, it's 2 to 3 Ms per kg, start at 2 makes per kg. It tends to be less potent than amlodipine. Therefore, for cats with severe hypertension, particularly if the blood pressure is over 200, I would say amlodipine should be at least part of the treatment, if not the total treatment, and we can use these drugs together, and that, that is definitely very frequently helpful as well.
The different formulation of cement, the fact it's a liquid can be popular with some owners. It's perhaps easier to dose titrate with that as well. And then lastly, just a very brief mention that ACE inhibitors do have some impact on blood pressure.
They're not licenced for this, but you probably historically have used ACE inhibitors in some of your hypertensive cats. They tend to be less effective than the licenced options. So, really, probably only lower systolic blood pressure by maybe 10 to 20 millimetres of mercury.
So in answering this question overall, which agent should I use? Amlodipine is the one with the best proven track record for really being a very potent anti-hypertensive medication, generally extremely well tolerated. So adverse events are very rare.
You can see there's a comment here about cat with a gingival hyperplasia that has been reported in the literature that was reversible when I'm he was stopped, but that is, you know, it's very, I think in my experience, unusual to see side effects with, with Amadi. Talbasartan is also very effective in treating blood pressure, but it tends to be less potent. So, we would probably not want to use it for cats with really terrible hypertension.
But now as I've already mentioned, is even less potent and is not licenced. So for cats with with severe hypertension, amlodipine is definitely the treatment of choice for me and also for the ACBIM guidelines. But there are certainly some cats that need more than amlodipine, and this is where cement and combination can be helpful.
If using the two in combination, then I tend to start with one Mg the king of Talmisartan, initially and monitor before potentially increasing to, to that 2. Makes the kick dose and make sure that the cat is well hydrated because as we know from from our treatment of kidney cats that antensin receptor blockers do have an impact on our renal chemodynamics. So if our patient is dehydrated, that could precipitate a renal crisis.
So we need to make sure our patients are are state if they have renal disease that it is stable and that they're not dehydrated. In general, I monitor blood pressure, about a week after starting treatment. And ideally, in terms of my sort of perfect goal, I want their systolic blood pressure to be within that reference range of 120 to 140 millimetres of mercury.
But as long as it's less than 106. And the cat is free of ongoing target organ damage, then, then, you know, that is adequate. If the blood pressure remains above 160, then I may increase the dose of amlodipine if I've started on the lower dose or add in a second medication, such as Seintra.
And, some cats will have blood pressure that that goes below 120, but if not clinically symptomatic for hypertension, I don't always adjust the dose, but I do speak to him about looking for signs of hypotension, such as the cat being a bit lethargic or a bit floppy, in which case definitely we want to back off treatment. Where possible, in our hypertensive cats, we do want to evaluate the cat for presence of underlying disease that may have either caused or have an association with the hypertension, because, of course, there are benefits in treating that. So looking for things like hyperthyroidism, chronic kidney disease, etc.
Is, I think, an advantage for the cat where it all possible. And if we can identify anything and we can manage it, then I think that has a positive impact on the prognosis for that individual cat. Another component of our prognosis is of course, of course, the visual deficits, because we so often do see these cats with visual deficits and blindness.
And one such example is Neo here, who you can see the time this photo was taken, hugely dilated pupils. He was completely blind as a consequence of his hypertension. And following treatments, in this picture, where you can see his pupil size is now much more normal, and he did regain some vision.
It's probably not brilliant, probably not optimal from what we could see going on the back of his eyes, but he was able to function much better in terms of his eyesight. And I included some data on this slide really alongside Neo from a fairly recent publication that looked specifically at the prognosis for ocular disease, and had 88 cats, so quite a number of cats, and some of these cats have been blind for quite a long time, more than 2 weeks for 41 of the eyes, they sort of reported it according to to the eyes, rather than the whole cat, and a variety of pathologies described as we've seen, but from a prognosis perspective, about 60% of the eyes that were blind regain some vision following treatments. So, you know, Maybe you, from a client perspective, say 50/50, but, you know, it's a bit more than 50% regained vision.
And indeed, of those eyes that were visual at the time of diagnosis, 93% of them maintained vision to the last follow up. So, in other words, the treatment was able to prevent further damage, which is, of course, very reassuring. So in conclusion, hypertension is common.
It is serious. It is, I think, relatively straightforward to diagnose, although there are definitely some pitfalls associated with our methodologies for measuring blood pressure and also the situational hypertension in particular, that can be a big headache for us. Once we've confirmed the diagnosis, actually, usually this is a very straightforward and very rewarding condition to manage, and even those cats that are completely blind, and this cat you saw a different photo of earlier on that had the complete retinal detachment, is another example like Neo, where you can see, following management, she did have some return of her vision, not perfect, but certainly an improvement, and an improvement, therefore in her quality of life.
So there's, there's lots of positives even for those cats that are blind. And the final slide, which I'll leave up for for any questions as well, really just a reminder of on my website, how to access some of the resources I've mentioned. So all the sort of free to access stuff is under this helpful info top menu.
And if you go to the video tutorials, you'll see how to perform an eye examination, how to measure blood pressure, short videos. If you also look in the subsection, it's called 10 Minute tips, you'll see some of the. Webinars I've done for veterinary professionals that might be of help.
And similarly, thinking of your owners, I've been running a virtual cat cafe for the last, year and a bit, so it's a sort of COVID, initiative, where we do, initially it was weekly, it's now monthly, a little bit of CPD for owners and some discussion, and there are several on hypertension in the cat cafe section, which you might find helpful to refer your clients to. Also free to access our the ISFM consensus guidelines on diagnosis and management of hypertension in cats, which if you just Google ISFM consensus guidelines, you'll be able to find them and download those. And similarly, the AC I am consensus statement on hypertension, which I think is is really Excellent.
It's a I think a couple of years old now, and it's really readable in contrast to many things that are published in the Journal of Veterinary internal medicine that I think can be quite hard going. This I think is a very practical and readable resource. So if this is a topic of interest to you, then that could be of interest to to look up.
And I'm going to stop speaking now and see if there are any questions at all that I can help with.