Good evening, everyone, and thank you for joining us for tonight's BCVA webinar. My name is Sarah, and I'll be chairing the webinar tonight. Our speaker Keith is happy to remain online for questions, so please type any that you may have during the the webinar in the Q&A box, and I'll save your questions for the end of the presentation.

If you have any technical difficulties, please let us know by using the Q&A box and we will do our best to assist you. If you can't see the Q&A box, if you move your mouse, the taskbar should become visible at the bottom of the screen. So it's my pleasure to introduce Keith Cutler as tonight's speaker.

Now Keith describes himself as just a cow vet, by way, by way of a short introduction, he qualified from Bristol University Veterinary School in 1990, having also gained an intercolated degree in anatomical Sciences. Shortly after graduating, he joined the Farm animal department of Endel Vett Group in Salisbury, where he remains to this day, having become a partner in 1998. Keith interests are many and varied, and includes suckler herd management and control, bovine lameness and Youngstock Health.

He is also past president of BCVA, a diplomat of the European College of Bovine Health Management, and a previous recipient of the Farmers Weekly Livestock Adviser of the Year. He is the director of checks and chairs their technical committee and sits on the advisory boards for both BBD Free England and Action Yoni. This makes him a perfect speaker for tonight's topic, TB, badges and checks.

So now to hand over to you Keith. Thank you, Sara. So, just to start, for those of you who know me, you will know how much I love IT, so I'd like to start with a thank you very much to the staff of the webinar vets who have held my hand through all of this, getting me online and making sure it's going to work.

So fingers crossed, but they're there to step in if something goes wrong. For those of you who don't know me, yes, I'm in practise in the central south of the country in Salisbury, a little market town which nobody had ever heard of until 2 or 3 months ago when the Russians came in, and we've had some fun. I started work here nearly 30 years ago, so 1990, and at that time, the whole of our practise area was on four yearly TB testing.

So adults only. No young stock, no pre-movement testing. It didn't matter if tests went a little bit overdue, a little bit meaning months, possibly even years.

And we very rarely found inconclusives or reactors. We then stopped TB testing in 2001 ft and mouth came along, and the one thing that didn't move in foot and mouth, certainly in this part of the country were cattle. When we started testing again after foot and mouth.

We started picking up reactors, particularly across Salisbury Plain. And how would this happen? So we're now in a position where the whole of our practise area is on annual testing.

Some of it is actually on 6 monthly testing now. We'll come to that later. We have a significant number of breakdowns.

We have herds on repeated short interval testing, and it's not unusual for us to find reactors and have confirmed cases of TB. So from a vetting practise point of view, how have we got to this position? Why are we where we are when a generation ago, the country was almost free of the disease.

And we are where we. We are with other diseases because of how we've managed the situation. We've implemented effectively at a test and cull strategy and paid little attention to other facets of the disease, the epidemiology, how we control it.

And of course, we can shoot our way out of an acute situation, but if that is all we do and we don't change how we might manage the situation, then we will get back to where we were fairly quickly. So we need to change something. So moving on, bovine TB is an infectious disease of cattle and other species, including man, and, and I've quite an interest in this because my mother caught TB as a young girl drinking raw milk.

Fortunately caught it in her bones, not her lungs, had several operations on her legs. She's left her with one leg shorter than the other, but it's given me a reason to, to try and Look at this disease. So caused by mycobacterium bogus.

I would argue, of course, that vets are best placed to advise about and enact control and eradication. It is, after all, an infectious disease, and we're very good at advising about and enacting control and possibly eradication of many other infectious diseases. So why should TB be any different just because it's a statutory disease?

It is an infectious disease. And government policy, I was asked to update on government policy, but this remains the eradication of the disease by 2038. And there are various prongs aimed at achieving this.

So there are cattle controls, there's vaccination, there's badger controls, there's biosecurity, which perhaps has been the missing link over the last many years, and then risk-based trading. So just have a quick review of bovine TB and Mycobacterium bovis, Mycobacterium bovis, the cause of this disease. It's a typical mycobacterial organism, and of course, we deal with others in, in the farm environment, particularly mycobacteria, maybe in para TB.

The cause of Yoni's disease, and there are many parallels between these two diseases. So mycobacterial organisms, Mycobacteria and bovis, can survive for long periods of time in the environment, that causes challenges in itself. It often has a slow progression to disease following infection, which may be measured in months or even years, and some cases of infection do not progress to clinical disease.

So World Health organisation estimates that about a third of the global population of humans is infected with Mycobacterium TB. But we don't see a third of the global population of humans progressing to clinical TB. We know also with mycobacterial disease that treatment is difficult, effectively not possible in the veterinary sector.

And we know that vaccinal protection is poor, so we have to look at what we're expecting from our vaccines. Vaccines are used in many different ways. So, are we expecting vaccines to protect against infection?

If we are, perhaps we need to think again, or are we expecting vaccines to protect against clinical disease or delay the onset of clinical disease and reduce the severity of its clinical symptoms? We also have the, the challenge that diagnostics lack sensitivity. The tests we have available are poor or even useless, you hear that said a lot, but I will argue later that actually that's not the case.

So microbacter and Bovis Bovine TV presents challenges. But as we've said before, it is an infectious disease. Just like any other infectious disease control depends on several key factors.

It involves on identifying and removing reservoirs of infection. It involves breaking transmission pathways. And then it involves preventing the reintroduction of disease by security elements.

And I would argue that's the same for pretty much any infectious disease. If we can identify and remove the reservoirs of infection, we can break the transmission pathways. We can reduce prevalence of disease, possibly eradicate it, and then if we can prevent reintroduction, we will keep herds clear.

So moving on to some of the government policies, the cattle controls. What have the government proposed? As the cattle control prong to aim for eradication of this disease by 2038.

In the edge area, my practise is partly in the edge area. Many of you listening will also be in a similar situation and you will already be aware of this. There's an increased use of gamma testing on all breakdown herds in the edge area.

The skin test is, is the commonly used diagnostic test, laid down in European legislation. Will that change in the future? But then we're using gamma testing to look at an earlier component of the immune reaction.

That adds complications when trying to explain this to farmers, the possibility of increased false negatives, or is it that we're finding the disease earlier in its progression and taking out animals infected, but no visible signs of disease before they can spread it. So more use of gamma. There's an increased frequency of skin testing, so the edge area is already testing every 6 months.

That's to be followed as soon as practicable is the latest pronouncement from government. They did say in 1919, which was commonly interpreted as going to be at the beginning of the year, but they're now saying as soon as practical by a similar increase in testing frequency in the high risk area. So, with some, exceptions, farms are going to move to testing every six months.

In the high risk and edge area that aims to identify infected animals earlier in the course of the disease before they shed so much infectious agent to other animals or into the farm environment and therefore slow down the spread of the disease. And there's been an introduction of post-movement skin testing of all cattle moving from the edge or high risk areas into the low risk areas between 60 and 120 days after movement. That time lapse is, is to allow the immune system to respond to challenge or infection.

And make sure that the skin test will identify disease if it's present. So those are largely already in place, those measures. The The increased frequency of skin testing in the high-risk area has been possibly slightly delayed because of possible concerns about veterinary manpower and our ability to deliver.

It will be a challenge, of course, but my experience of the veterinary profession is that when push comes to shove, we stand up and we do manage to deliver. So we need to look at testing performance. I hinted at, the possibility of false negatives and in, in the last slide, and the slide before that, I, I hinted at the fact that the tests we use are not, are not very good.

All laboratory tests have a sensitivity, a specificity, and a predictive value, and we need to understand these terms and be able to explain them to our clients to make sure they understand them and how we deal with disease. And the skin test for bovine TB is no different. So sensitivity.

In farmer terms means if the disease is there, will the test find it? It's a measure of false negatives. Specificity means in farmer terms, if the test says the disease is there, is it really there?

It's a measure of false positives. These two are a function of the test. They go hand in hand.

You can increase one at the expense of the other. So we need to understand what we want of sensitivities and specificities. And when we're trying to eradicate a disease, I would argue that actually we need high sensitivities.

While it's undesirable to have too many false positives. Is that a complete disaster? If by making sure the sensitivity is as high as possible, we take out all diseased animals.

For BVD, for example, if we miss a single PI in an eradication programme, it's a disaster. We have to have the sensitivity at a level where we will not miss a PI. If that means we shoot the odd animal, that's not a PI, at least we've achieved our aims.

It's a little more tricky with mycobacterial disease, with TB and with the O's disease. But we need to consider how those two. Work against each other.

We then need to look at predictive value. So predictive value is not a function of the test. It's a function.

Of this in the population. If the disease is not present in the population, then every single positive result will be incorrect, the positive predictive value will be zero. If every single cow in the population has a disease, then every single positive result will be correct.

The positive predictive value will be 100%, and vice versa for negative predictive value. The difficulty we've faced often is that we don't know the prevalence of disease within the population, and we have to make some assumptions and best guesses. And there's lots of ways of doing that, particularly looking back at at previous.

Test results, testing history on the farm. So predictive value is how likely is the test result to be correct? Our major test for bovine TB is a single intradermal comparative cervical tuberculin test, where We use the margin between the anterior and middle third of the cow's neck.

We make clip marks, we measure skin thickness, and then we inject intradermally blebs of avian and bovine PPD and we compare the tissue reactions. We have to remember that this was designed as a herd level rather than an individual animal test, although there are now many situations where we use it as an individual animal test. So that has to affect our understanding of interpretation to some extent.

We know from work carried out that the sensitivity of this test is between 50% and 60%. That's not terribly high, so false negatives are not uncommon. We need to understand the limitations of that.

When we move that up to a herd level though. The sensitivity on a herd level is much higher than this. Specificity however Is well over 99%, 99.9% is often quoted.

This means false positives are very, very rare. So when we see reactors. We have to believe them and, and they go off and get slaughtered, usually within the government's 10 day target.

And often these are reported as NVLs. And farmers' interpretation of this is that there was a false positive result. When we look at specificity of 99.9%, it's very unlikely that that was a false positive result.

It may be, of course, that we need to explain a little bit about what we're testing for. So we're not actually testing for clinical tuberculosis, we're testing for immune and immune response to challenge by M. Bovis.

So that may be that the immune system reacted and eliminated infection. It may well be that there is latent infection sat there in, in a lymph node somewhere with only a few bacteria that would not be very easy to find. And even culture negative NVLs don't necessarily mean that the test was wrong.

In fact, the test is highly likely to be correct. So looking at predictive value, standard versus severe interpretation, the severe interpretation increases the sensitivity of the test, perhaps reduces its specificity a little, but we use that in herds that we think we know that TB is present, that increases the predictive value. And so that makes us more likely to take infected cows out of the herd.

I would also have a query here about the amount of retesting of inconclusives that goes on. So, in years gone by, inconclusives were allowed to be retested, and if they were inconclusive for a 2nd time, they were allowed to be retested a 3rd time. And if they passed that 3rd test, then they were deemed to pass the test.

But we have a highly, highly specific test. False positives are very rare. So why do we continue in the situation that we're trying to eradicate a disease?

To look for the result we want to have, we want the cows to pass the result. If our real aim is to eradicate this disease, perhaps we should be a little harsher on some of our interpretations. That may not be to everyone's taste, it certainly may not be to my client's taste.

But if they want to get rid of this disease, if they have an inconclusive that passes the test, few. You stayed on your annual, your 6 monthly testing. But if you're serious about getting rid of TB, I wouldn't have that cow still present on the farm at your next test.

And the same for Yoni's disease, a blood test positive cow that passes its faecal confirmatory test is still a high risk cow to keep in your herd. So we need to understand how these tests work and how we interpret them. Are they useless?

No, they're not. Is how we use and interpret them use this. You're all, I presume very experienced vets probably know far more about this than I do, but I would wonder whether sometimes we are a little lacking in how we use and interpret these tests.

And then compliance with the SOP, so. Do we get our labs intradermally, how accurately do we measure? And of course we all measure really accurately on day two, when we've got a dodgy cow.

But callipers are not. That accurate, accurate to perhaps plus or minus a millimetre. And what's the point of measuring that accurately on day two if we haven't measured that accurately on day one?

Or is there a tendency to squeeze our callipers a little bit? So operator input can have a huge influence on how this test performs, and we all know what we're doing there. We do have other testing options.

We mentioned gamma earlier, so gamma interferon testing detects an earlier component of the immune response to challenge or infection from the skin test. It's still a very, very specific test, but because it's detecting animals at an earlier stage of infection, we will have more NVLs. And how often do you hear farmers say, I've been offered gamma testing, but I don't want it because we'll get more false positives and I'll lose even more cows.

We now have a, an option coming of age testing. I think this is a really clever option. So phage, viruses are obligate parasites of bacteria.

So for phage testing, we use phages that are obligate parasites of mycobacteria. So we take a blood sample, could be other samples, but a blood sample, and We add phage to it. If the phage reproduces, we know there are mycobacteria there.

And this test is reported to have an extremely high sensitivity of down to about 5 or 10 bacterial cells per mL of blood, exquisitely sensitive. If the age reproduces, we know there are mycobacterial cells there. We don't know which mycobacterial cells.

But part of the beauty of this is that the phage in its reproduction, as it bursts out of the cell, bursts the cell open, releases the mycobacterial DNA which can then be typed using PCR to determine whether it's M bovis or MAP or another mycobacteria. So phase testing, where does that come in? Would those be better options?

Than, another skin test for IRs, would they be better options for post-movement testing to give our clients, A, a better, reassurance that they're not bringing disease onto their farms. So we need to look and understand what testing options are available to us. Vaccination is another prong of the government's strategy towards eradication of this disease.

It's based on BCG and some of the audience, some of the, the older ones like me, may well have had BCG vaccine when we were school kids, but there is currently a worldwide shortage of BCG vaccine. And all the time there is a demand for human health reasons. We're not going to have this available to us for vaccinating cattle or badgers or other animals.

So, worldwide shortage, we need to understand that vaccination may prevent or delay the onset of disease, but it does not necessarily prevent infection. So is it driving the disease underground? Is it hiding infection while compromising our ability?

To test animals if we're using immunological tests, so the skin test, yes, it will. One of the beauties of phage testing is that it only tells you whether there are viable MAP organisms present or not, so vaccination will not affect phage testing, for example. Even if it's available, delivery to badgers is challenging.

So the route of administration and, and there's lots of work been carrying on with oral delivery, but that's not perhaps the best means of delivery to, to mount an immune response. And it's 10 years away, and to my knowledge, it has been 10 years away for at least the past 30 years. So, are we getting close?

Of course we're getting closer, but is it gonna be here tomorrow? No, of course it's not. I would also argue that with the millions of pounds being spent on human TB vaccine research to optimise vaccine performance, and we're still not there with human TB vaccination, what chance really do we have in cows and wildlife?

So is vaccination a red herring? And that may be where we are with other mycobacterial diseases, solonis disease as well. We then move on to to badger controls, which is another big part of government policy.

So it's always been. Of interest to me. I've never understood why when there, there's an infectious agent, sorry, bovis, that we know infects cattle and cattle can transmit it to cattle.

We know it infects badgers as well, and cattle can transmit M. Bovis to badgers, Badgers can transmit it to other badgers, and badgers can transmit it to cows. Why?

Do we concentrate exclusively on controls in one of the host species in cattle and almost ignore the other host species? And these links have have been Known about for for many years and and written about in some of the most influential papers about this, so Krebs, which was, Deemed to say that badger controls were not going to be significant in the control of, of M. Bovis, said that there is strong circumstantial evidence to suggest badgers represent a significant source of M bovis infection in cattle.

So I understand scientific rigour and proof. But, there are many others, the, the ISG badge identified badgers as a source of cattle TB . So even the papers that are anti-badger controls all purported to be anti-badger controls, acknowledge a large role for badgers in this, but they mention perturbation a lot, and, and to understand this, we have to understand badger.

Biology. So removing badges from an area encourages more badgers from the surrounding areas to move in. If the population of badgers on your farm is disease-free and stable, removing them may allow diseased badgers to come in, and that will increase the disease transmission risk.

So if we're going to start culling, and we're going to avoid perturbation, we need to have culling areas that have hard boundaries as far as that is possible. Badges can cross roads despite the numbers you see lying on the side. They can swim across rivers.

So hard boundaries, hard being a relative term, and culling needs to be ongoing. And we're seeing the benefits of culling now in, in some of the government licenced cull areas and this is part of the ongoing government strategy where more areas are being licenced. So culling, Badges makes perhaps little difference, a minor difference to the prevalence of TB amongst the cattle in those areas in the first year.

You can start to see, to see a difference in the second year. By years 3 and 4. You can see quite a dramatic decrease in the prevalence of TB amongst the badges, but the culling amongst the cattle, but the badges, the culling of the badges needs to be ongoing.

To stop disease badgers moving in. So we have more culling areas being licenced, with even one being proposed in the low risk area of the country now, and we have more areas ready to go next year, when, when next year's areas are licenced. And as I said, the initial evidence suggests an increasing reduction in TB breakdowns in cattle herds in cull areas as the cull proceeds, with some particularly good results being seen in years 3 and 4.

And that mirrors the, the, the results in other areas, particularly some of the Irish work. But it's not all about killing badgers, . We need to, to look at other ways of preventing cow badger interactions, and those may be direct, although perhaps that's not the biggest risk, it's the indirect interactions that may be a bigger risk.

So we need to talk about badger biosecurity. We need to keep badgers out of our cow sheds and perhaps more importantly, our cow feed stores. So sheeted gates.

But there's no point sheeting your gates if you don't close them to keep badges out of cowsheds, we need to know to put the sheets on the outside of the gates, because if we put them on the inside, we still provide the. Bars from the badger to climb up and over the gate and get into the feed store. He then spends the night in there, can't get out because the sheets on the inside, but it'll run out when you open the gate in the morning.

So sheeted gates using electric fencing to keep badges away from signage pits, and, and it's interesting, isn't it, that the spread of TB mirrors the increase in badges, which mirrors the spread of growth of maize as a feed for our dairy cows across the country. We need to have the electric fencings put at the right height for badges. Badges can squeeze in through pretty little gaps.

So 5 centimetres, 7.5 centimetres, 10 centimetres. 30 centimetres, all, all the levels are, are on the websites to, to show you.

We need to make sure those electric fences are working, that they're not overgrown by weeds and nettles that they, the batteries are charged up. We can use badger proof feed and water troughs, keep minerals out of, out of badger's reach. So instead of putting them.

On the floor, particularly molassed minerals, why wouldn't you as a badger like to go and and lick a nice sugary solution, very tasty, . Fence off badger latrines. So M bovis can survive for long periods of time in the environment.

Badge latrines act to concentrate M bovis if the badgers are infected. So we need to fence these latrines off, keep cows away from them, and equally, don't overstock your grazing. If you graze too hard, you'll push your cows into the field margins and the hedges to to source forage, and that's where often badger latrines and badger runs are.

So a few slides of the TB advisory websites, which I'm sure you'll all be familiar with. Don't leave maize gluten or your cake lying around in your farmyard. What's easy gets done, what's difficult doesn't get done.

So if badgers can find food lying about for the taking, they're going to make the opportunity of that, and they're going to rub their open weeping skin sores. In that feed, they're going to urinate and pass the millions of bacteria in their urine into cattle feed, which is then going to be fed to cows the next day. So keep your farm yards clean, keep your food stores secure.

Sheet your gates. Put electric fencing round your silage pits with the right gaps between the wires. Couple of pictures here just to show how narrow a gap badges can squeeze through.

So here, the farmer has done what he's thought was a good job. He's put wire mesh up on his fences, mesh size small enough to keep badgers out, buried it in, in the ground, so badges won't bury underneath it, but there's still a gap big enough between the gate and the post at the hinge end for the badger to squeeze through. They only need about 5 centimetres.

Raise your, your drinking troughs up so badges can't get in them, make them higher. Put roll bars on your feet trough, so as the badger puts his feet up to gain access, the bar spins round and, and, He falls off. All these things are doable, they will reduce the number of badger cow or cow badger interactions, and that will break transmission pathways for this disease.

You'll all be aware of raised feeders for mineral blocks so badges can't reach them and there's a whole variety of these now available. Fence off badger latrines and badger sets. A further prong of the government's approach towards eradication of TB is risk-based trading.

And this is where checks comes in. And I have a vested interest here. I'm, I'm a director of checks.

But I believe checks has been very successful with non-statutory diseases. Czes has always looked at BVD, IBR, lepto, yoni, and Neosporra. We've always kept away a little bit from TB, the statutory diseases.

They're under government control, aren't they? But the government has noted. The success that checks has had with the non-statutory diseases.

And, and involved the checks team now. So why checks? We have an established record of providing programmes for management and possible eradication of other diseases, BVD particularly, and then certifying herd health status.

I'm sure you'll all be familiar with with the acronym Cattle Health certification Standards. It was established in the late 1990s by a consortium of the British cattle industry. That includes BCVA.

If you're a BCVA member, and presumably you are, if you're listening to this webinar, you part own checks. It's owned by Holstone UK, National Cattle Association, dairy, and the National Beef Association. So a consortium from the British cattle industry, it's a non-trading not for profit organisation run on scheme licence fees, self-regulating.

It's not in itself a health scheme, but it provides rules to which all licenced health schemes must adhere. To give some sort of repeatability. An accredited free health status with one health scheme under checks rules will be the same as a, an accredited free health status with a different accredited a licenced health scheme.

The aims of checks are very simple to promote improvements in cattle health and welfare. Doesn't that fit nicely with the government's policy of eradicating It provides standards and certification for cattle health schemes. And it aims to develop and maintain links with everyone involved with cattle, health and welfare.

So farmers, breed societies, vets, laboratories, the government, animal welfare organisations. So we all work together towards a common goal. And how often do you find people who are supposed to have the same aim all pulling in opposite directions and going nowhere?

The nutritionist wants more milk, the vet wants better fertility, the farmer wants less input costs. You sit there in the middle going precisely nowhere. If you can align your aims and direction of travel, you're gonna make progress, aren't you?

So the checks technical document, this is updated annually by the technical committee. It's freely available to everyone on the internet. It's made up, updated annually by the technical committee and independent chair, representatives from each licenced scheme who bring in laboratory expertise.

They know what tests are available. They know how those tests perform. They know how to interpret test results.

Slightly different for TB because we've got vets, OVs out on farms performing the skin test, which adds a layer of complexity and variability in that. And then there's invited independent experts on the Czechs technical group to bring disease-specific expertise. So various people, Richard Booth, for example, from the RBC.

Brings, I've got a little bit of a problem, I think, has anyone else got a problem, . Brings expertise. From the BVD point of view, others George Cowdo brings expertise from a Yoni's disease point of view.

My pictures come back, thank God for that. The Czechs technical document then introduces the Czechs diseases, . So we've got the big 4 that we spoke about earlier, BVD IVR, Leptoyonis, we've added Neosporra a while back and then more recently, just over a year and a half ago, TB.

The checks technical document then sets out general rules of certification, testing, what do we test and when, and biosecurity. And perhaps this is the big difference between what's been going on with TB in the past and now. So, Essentially, we were running a test and cull strategy with biosecurity left up to individual vets and farmers.

Barsecurity is an enormous part of, of the checks protocols. And then there's disease specific programmes and testing, and they're different for the different diseases unsurprisingly because the different diseases work in different ways. The programme aims to establish and monitor the health status of a herd.

That sounds obvious, but for different people, that means different things. If you're a purchaser, you want to know as best as possible the status of the herd you're purchasing from, so you can make a risk assessment. If you're a vendor, you may want your health status to be as high as possible to give yourself a marketing advantage, God forbid.

So we need to be aware. Of how figures can be massaged. It then provides a framework to assist in management, improving herd health status, and that may lead to the eradication of one or more infectious agents.

Some of them eradication is going to be difficult. Is that an unachievable aim? Because if it is unachievable, if we aim for it, we're going to end up in tears with everyone involved.

So, let's be honest about what we can achieve and what we can hope to achieve. And then to accredit health status. So general rules, we define herds.

And that's not as easy as, as you may think. Many farmers, particularly suckler farmers, will have a small herd of pedigree cattle running inside a herd of commercial cattle. What's the contact there?

How can we define one as a different health status to the other? Should we be talking about epidemiological units? The problem there is particularly with boundary biosecurity and government works on CPH numbers, not on epidemiological units.

Certification, transparency only sign what you know to be true. And all relevant test results and changes in herd management must be notified to the scheme provider. It's no longer, never was permissible, but it certainly is no longer permissible to do a pre-screen.

Sort out which animals you want to keep and which you don't, and then do your official screen on the animals you've kept. And testing rules, which animals to sample, what samples to be taken and when different for the different diseases because of their differing epidemiologies. And then biosecurity is a huge component of this.

So particularly boundary biosecurity and contact with animals of unknown health status. A checks accredited health status is only as good as the lowest health status of animal your animals have come in contact with. So how do we achieve this?

Everyone says we need 3 metre boundaries. Why 3 metres or 3 metres because it prevents nose to nose contact is 3 metres enough? Well, patently it's not when exclusion zones for foot and mouth for 10k and bluetongue and Schmalenberg can blow in the midgies across the Channel.

But it helps and it shows a mindset, are farmers going to double fence all their boundaries? No, of course, they're not. There's a huge cost even in electric fencing to double fence boundaries, .

But actually, you don't need to do that. You just need to talk with your neighbours, and it may be that you can arrange that you will graze your boundary field while your next door neighbour shuts is up for silage next year, you'll do it the other way around. Or perhaps you could even agree that you will aim to control and then eradicate a particular disease at the same time, even better.

And then there's added animals and quarantine facilities. And how often do we really manage a quarantine facility? What does quarantine really mean?

Does it mean the dingiest, darkest hole at the furthest reaches of the farm that you put the animals you've purchased in, you throw them a couple of wads of hay 2 or 3 times a week, so long as they eat that and they walk out at the end of quarantine, and how long should quarantine be, they're fine. Or does it mean? Wild animals are in quarantine, we actually look at them critically for signs of disease.

We do some blood testing to define their health status. We act on the results of that, which may not always be what we want to see. We implement prevMed strategies, so we protect our herd from them.

And we protect them from the health status of our herds. So quarantine is a proactive process. There's more rules about grazing and feed, including lossum, water and bedding management, visitors, including vets, and how often do we spread disease?

Many, many years ago, a young assistant working with me, had a bit of an incident with a trail of salmonella that followed him around some farms for a couple of days there, but for the grace of God, I fully admit. But that was a salutary lesson. How much digital dermatitis have we as vets spread on improperly disinfected foot knives?

So we need to think about things and shared facilities and equipment, including veterinary equipment, and I have a particular bee in my bonnet about slurry spreaders. So how often does a slurry spreader that you hire come cleaned and disinfected or even cleaned? And how often does it come half full of shit from the previous farm and the first load you spread on your fields is that ship from the last farm including all the pathogens that it contains.

And then wildlife, of course, and back to badgers when we're talking about bovine TB. So for TB, the, the checks, risk-based trading is based on a risk level defined on the number of years that a herd has tested free of TB up to a maximum of 10 years. And there's good evidence in the literature that once you've been free of TB for 10 years, it is highly unlikely.

Not impossible, but highly unlikely that a reservoir infection remains in your herd. So a risk level depending on the number of years a herd is tested free of TB, and this aims to allow more sensitive assessment of risk than simply the location of herds. Is it a 4 yearly testing parish or a yearly testing parish, or a 6 monthly testing parish now?

And this allows for the herds on farms within the high risk areas of the country that have consistently tested free of TB for years, despite being in an annual testing location, to make the most of their higher health status. It also allows us to Acknowledge the risk of herds in low risk areas of country that buy in animals with very little in the way of biosecurity precautions. So the checks, TB rules, statutory testing remains in place.

Post-movement skin testing between 20, sorry, between 60 and 120 days after import is compulsory, and animals can remain in quarantine for that period, or they can be released from quarantine. If they're released from quarantine and an animal fails a post-movement skin testing, their, the herds checks risk rating goes right back down to zero. If the animal is in quarantine and fails its post-movement skin test.

Then the checks herd risk rating will remain the same because the animal never left quarantine. Government can't cope with that at the moment. Government struggle with quarantine.

And that's because quarantine means different things to different people, and we've not been very good at it, historically, but government work on CPH numbers. So if you purchase animal fails the skin test in quarantine, the whole of your herd goes to increased statutory testing, but your checks risk level stays the same. .

There's an option to use gamma testing, not in Wales, of course, but an option to use gamma testing before that to increase the, the reliability of that. And possibly, that's where we should be looking to use age testing now to get the most sensitive possible test that we can. Quarantine, we talked about options on that, so.

Animals don't have to stay in quarantine, but if an animal leaves quarantine, joins herd, and then fails the test, the check's risk level of that herd goes right back to normal. And quarantine's interesting here, I would argue about whether quarantine is actually achievable when we're buying in, for example, freshly carved dairy cows. Of course, we can keep them in the box, but they still need to go through the parlour.

Therefore, they'll be close to the parlour. Therefore, there's likely to be some sort of contact between animals. So we need to be clearer on what quarantine means and what we're trying to achieve.

There's rules about grazing management, so, checks accredited TB herds should not be grazing pastures that have been grazed by non-accredited stock within 2 months of being grazed by those non-accredited stock. And then we need to maintain farm boundaries and how often do our clients rely on virtual fencing, which cows don't seem to worry about. So we need to maintain our farm boundaries to prevent nose to nose contact at least between animals of unknown health status and our checks accredited animals.

We also need to have a specific TB herd health plan to reduce risk, and there are various people available to do this TB Advisory Service, but I would argue that the person in the best place to put this plan in place is the farm's own private veterinary surgeon. He will know more about how that farm is managed. And the challenges on that farm.

Then there are advisory elements to the checks programme. So grazing management, avoid high stocking densities and overgrazing. We've talked a bit about that in minimising the cow badger interactions, .

Don't co-graze with other ruminant species who can become infected with bovine TB. And I've added in here all camelids, so for those of you who are also working with alpacas, you'll be very well aware of the situation. There and the difficulties of testing those again.

The huge, . Swell of opinion amongst camelid owners of false positive results. Are they really false positives or are they true positives where we, we can't find signs of disease?

And advisory that you should not spread slurry on grazing land makes sense. And then badger proofing your feed troughs and your mineral licks, your, your silage pits, your concentrate stores. Water, where possible, we should provide mains water.

We need to keep our water troughs cleaned out and badger proof our water troughs so the badges don't drink and dribble in our water troughs. Housing and feed stores solid sides, so badges can't get in sheet and close the gates and electric fencing, the things we talked about earlier in reducing cow badger interactions. And then badges restrict as far as is possible access by cows to badger sets, runs and latrines.

Don't graze your cows right into your field margins. Don't allow cattle access to woodland. And if you do come across dead badger carcasses, dispose of them appropriately and responsibly.

Advantages of the CES TB scheme membership. There's a greater recognition of the efforts that have been made to reduce the risk of TB in your herd. And that may be just a matter of pride for the farmers.

Most of our clients take great pride in looking after their cows as well as they can. There's a less onerous requirement for statutory testing. So in the edge area where we've already moved to six-monthly testing.

The farms who have a checks accredited TB risk level will remain on annual testing. So a concession from the government to the benefits, particularly of the biosecurity that the check scheme involves. And there's a greater reassurance about the TB status of animals you may be selling.

So that may lead to having a greater pool of potential purchasers. Looking at your stock and that may result in a greater potential value for your stock. So that's where I'd like to finish.

Have I given you a load of answers? No, I probably haven't. Have I given you some food for thought?

Hopefully, I have. Hopefully I've persuaded you to think about this disease in a slightly different way, just because it's under statutory control doesn't mean it's not another infectious disease to be controlled in the same way as many of the other infectious diseases that we already work with. So, we need to identify reservoirs of infection and eliminate them as far as we can.

We need to break transmission pathways, particularly reducing the number of cow badger interactions, and then we need to prevent the reintroduction of disease by implementing our biosecurity. Measures. And if we can start looking at this disease in a different way and changing how we manage our herds of cows, perhaps we have a real possibility of achieving the government's target of eradicating the disease by 2038.

So, thank you for listening. I guess Sara will have some questions which I may or may not be able to answer, but I'm willing to have a go. Thank you, thank you, Keith, that very, very interesting presentation and I'm sure that, everyone watching it has really, really enjoyed it and found it very useful and certainly give us food, food for thought, particularly when it comes to interpret interpreting the testing results.

So don't forget that we have got, a few minutes for questions. So if you haven't entered your questions already, please do so in the Q&A box, at the bottom of your screen. But just before we do go to questions, could you please spare us 30 seconds of your time just to complete the feedback survey that should have popped up in a new tab in your browser.

Depending on which device you are using to watch the webinar, the survey doesn't always present itself. So if that's the case, just please feel free to email any feedback that you have using the email office at the webinar vet.com.

If you're listening to the recording of this webinar, you can add comments on the website underneath the recording or email the webinar vet office. So over to questions, don't forget to keep them coming in. Comment here from James Russell, he says, hi Keith, good session, thanks.

Early. Discuss the need for a highly sensitive test for eradication. He agrees, but do you fear that given the need to obtain statutory freedom to achieve OTF status in an area that we cannot afford to trade sensitivity for specificity, or are, or will we never test wholly clear?

They're difficult questions and they're bound to come, aren't they? And it depends on your priorities. So, are we aiming to eradicate this disease?

Do we understand what we mean by eradicating this disease? So, the aim for OTF, does that mean that there is no TB there? My understanding actually is it doesn't.

My understanding is that it means that fewer than 1% of tests carried out will result in reactors and confirmed disease. So, so that's different. This is, this, I tried to portray this all the way through.

Are we aiming to eliminate, eradicate disease, or are we aiming to, to manage it at levels that are very low and acceptable to us? Parallels here with Jo's disease on there, . Of course, as we get further and further down that line, the positive predictive value James of the test, as you know, becomes lower and lower and lower.

So it becomes more and more and more likely that we do have false positives then, so as the prevalence of disease declines, we will get more false positives. And at that point, perhaps we have to change our definitions and our cutoffs. It depends what we're trying to achieve.

But at the moment, I would like a sensitive test at risk of shooting a few, of course, I don't want to shoot very many undeceased animals, but at risk of shooting a few undeceased animals, I wanna make sure I get the diseased ones. Thank you. Just on the subject of sensitivity, a couple of questions have come in about the sensitivity of the skin test and just asking for clarification of whether it is 50 to 60% or 80%.

If you could just expand. So I guess part of that depends on . At your interpretation, so standard versus severe, it will of course depend on who's doing the test and how hard you push your callipers.

It will depend on. Whether you're doing this on an individual animal or on groups of animals or on herds, but you look in the literature and you will find Sara, as you well know, all sorts of, Of figures for the sensitivity of this test. I'm less worried about the sensitivity, to be honest, than I am about the specificity, and the specificity is very regularly quoted as much greater than 99%, i.e., false positives are rare.

OK, thank you. Another question here, we won't be able to get through all the questions tonight, but just we'll try and get through as many as we can before 9 o'clock. One question here from Andrew said, you said that the checks TB accreditation would result in annual testing rather than 6 months in edge areas.

What about high risk areas? What will the testing interval be there? So the high risk area hasn't moved to 6 monthly testing yet.

That was announced some time back that we would start in 2019. The interpretation of that was that it would start in January 2019. The government has said now, they never said January.

I do suspect an element of backtracking. Mainly because of worries about manpower, I think, but they are saying that it is on the agenda and it will be started as soon as practicable. My understanding is that for herds in the high risk area who have a checks risk level accreditation, they will remain on annual testing just as they do in the edge area.

Who knows how that, who knows how that may change with the government. And another quick question, do you think that Yoni's prevalence complicates testing stroke results? Now, there's an interesting question, isn't it?

And I, it's usually one I have to answer the other way around. So does the TB test affect Yoni's results? The two bacteria that causes disease are both mycobacteria, And they're related.

Yes, of course they, they are. So there's the potential of cross reactivity. Farmers get very jumpy.

Yoni's disease is going to increase the prevalence of reactors in my herd, and I'm going to get loads of false positives. But if you think about it logically, Yoni's disease is caused by Mycobacterium avium para TB. So surely it's going to cross react more with the avian PPD than the bovine PPD.

So if anything, we're gonna get more false negatives on the TB test. So Yoni's disease is gonna hide TB and that's not good for us either. So I think that needs explained to farmers.

The flip side, and forgive me, I know we're talking about TB here, but, but I have a, a bit of a crusade about this is TB testing and the Yoni's test, and, and you get Loads of false positives on the Yoni's test. Well, sure, again, there's, there's cross reactivity, but there's a certain amount of anecdotal evidence, particularly from milk testing results. So in herds with a low Yoni's prevalence, yes, their milk test results will go up.

Shortly after a TB test, but they'll go up a small amount and perhaps into the inconclusive band. Herds with a higher prevalence of yonis, they will go, the results will still go up, but they'll go up by a greater magnitude and many more cows will go into the positive results. Are those false positives, or actually, have we increased the the sensitivity of the test?

By the preloading with the TB test, just like you do with vaccinations where you give the, the initial dose, you get a short-lived response, then you get the second dose of an initial course and get the an amnestic response. Have we done that with the TB test, and we're actually finding more true positives just an awful lot earlier than we otherwise would. And it's interesting to speculate, isn't it, that of course, I understand that's talking about yoni after a TB test.

And I understand yoni is not TB. I also understand that alpacas are not cows, but both diseases are mycobacterial diseases, and both species are mammals with vaguely similar immune systems. When we're serologically testing for TB in alpacas, we are actually told to go out.

And give an intradermal dose of bovine PPD to increase the sensitivity of the test before we take the blood for the serological testing. And yet, when we get to cows, we're very happy to say it's all false positives because of cross reaction. How does that work?

Thank you, Keith. Thank you very much, once again, that's all we've got time for, I'm afraid. We have got a number of outstanding questions, which, if it's OK with you, Keith, we'll, we'll email on to you, and then round everybody that's, participated this evening.

So I just want to thank you again, Keith. That was an excellent presentation, really, really useful, good practical advice. And, also thank you to everybody who has attended tonight's live webinar.

And we look forward to joining you at, for, for you to joining us again for the next BCBA webinar, which will be in September and is on the subject of motivational interviewing. So we'll see you again then. Thank you very much and good night.