Hi, and welcome to this presentation. My name is Kat Baxter Smith, and I'm a veterinary advisor at MSD Animal Health. I'm mainly responsible for the beef and sheep portfolios.

This presentation's going to be on pastoralosis and Clostridial diseases in sheep, and we're also gonna be focusing on, sudden death, the diagnosis of sudden death in sheep, and what samples and things you should be sending off to the lab. So learning objectives. We're looking at the causes of sudden death or the clinical signs that might lead to this happening, how you would diagnose it, and also most importantly how you prevent it.

The most common cause of all sudden death is actually pastoralosis, so we're gonna cover this in quite a lot of detail. So what do you need to do if you've, arrived on a farm and the farmer has said, I've got some sheep or a sheep that's died, apparently suddenly, and, they want you to sort it out and make sure that this doesn't happen to any of the other sheep. So, first of all, you want to take a really good history.

You want to get the age of the sheep that's died and the age of the group that the sheep is from. What breed are they? Are they male or female?

How many have died versus how many are in the group. You know, 5 might sound like a large number to die, but if it's from a group of 5000, sometimes you have to put these things into perspective. What is the time period over which they have died, as in, did they all die overnight or have they been dying over a few weeks?

Are they in lamb, and if they are in lamb, when were they meant to be lambing? Or, have they lambed, and when was that? And any history of clinical signs, farmers often say, oh they died suddenly.

Actually, if you question them a bit more carefully, you find out that they might have been off colour for several days or even longer. Other things that are really important to ask about, so things like body condition score, we do often see this, apparent sudden death in animals that are actually emaciated due to, poor nutrition and possibly also, worms. So I think this is a really key thing to be able to find out.

Are they at housing or are they at grass? Because this can help lead you down the path for diagnostics. What is the feeding history?

Have there been any sudden changes? Sheep are not particularly good at, coping with sudden change, so, that's a really useful piece of information. Anything that's happened in the weather, very rarely you will get things like lightning strikes.

It's much rarer than you would be led to believe, but any, large changes in the weather as in suddenly from warm to cold or cold to warm can certainly precipitate certain diseases. Vaccination history, are they fully vaccinated or are there things they're not vaccinated for? Treatment history.

Has the farmer given them any antibiotics or any anti-inflammatories or anything else that could have caused this? Sometimes, if the farmer has given certain products together, which may not have been, be licenced to be given together, they could have had a, a sort of anaphylactic type reaction, so that's always worth knowing. And any other management procedures such as dosing for worms, it is known that, farmers have been, in the past.

Dosed the sheep for worms and caused er lacerations in the throat, which can then lead to death. So what kind of what would be on your differential diagnosis list after you've taken this history. Obviously trauma, that should be, you know, that should be quite obvious if there is trauma.

You would see wounds hopefully or some kind of evidence of that. Neurological, so, you know, is the animal, if there are any live animals, are they showing any neurological signs? Is there, does the carcass look completely normal, or are there any, are there any sort of clues that could lead you down this path?

Bacterial, such as mastitis or metritis, so do make sure to check the other, on the back end. Anthrax is very rare but obviously is a cause of sudden death, and this is notifiable. So if you have any, inkling that there might be anthrax involved, do make sure you understand the procedure for this.

So if you want to get your, gold standard is is to get the whole carcass to a UK accreted lab. The more the merrier means that the more, the more samples or the more carcasses you can get to the lab, the better, because, often when we have a sudden death, the lab sometimes receive the carcass too late. There'd be a certain degree of degradation, and they might not be able to get a diagnosis.

So the more you can give them, the more likely you are to get a diagnosis and the more like the farmer is going to think it's worthwhile doing. If you can't send a whole carcass, then you want to get a decent number of samples. So definitely fresh and fixed lung tissue.

The most, what, as I said before, one of the most common causes of sudden death is pasture. And if you have, some lung that looks diseased, you want to get a, a piece which has got the border between diseased and healthy lung. Some swabs, so you can use some swabs to take samples from the trachea and the lung, and you should get charcoal and plain.

If you can get some pleural fluid, that's great. Intestinal contents, this would be really useful if you can get those for Clostridium profingence toxin. And, anything else, if you see anything looking like liver looking a bit dodgy, you know, kidneys looking a bit dodgy, anything that looks not quite right, takes them normal and abnormal, and then the lab can can compare them.

And really you need to get to the lab as soon as possible. If the animal died on the Friday and you're seeing them on the Monday, that's really too late, preferably you need to get fresh. And if there, if there isn't a fresh one, but there is some animals or an animal that looks on the, verge of, of dying, it might be worth sacrificing that for a postmortem.

If you have fixed tissue, that doesn't need to be quite so freshly submitted, so you can always keep those in the fridge until you know what the sort of diagnosis of the bacterial culture and toxin is. So we'll just go through a quick sort of procedure that you can follow for sudden death, because I think it's always worth when you're doing these, having a, a, a step by step procedure so you don't miss anything. It's very easy to miss things when you're on the farm and you've got the farmer chatting in your ear and asking what's wrong.

So first of all, look at the external body. Look at the mucous membranes. It's only discharge from the mouth or the eyes, or the other.

If you can get some faeces for faecal leg count, that would be really useful. Check the other, check for trauma such as broken leg or wounds. Check the body condition score.

As I said, many of these are emaciated. Aqueous humour would be from the eye. You can test that for, you know, certain minerals and, and things.

So make sure you take some of that if you can. Subcutaneous ecchymotic haemorrhage can be diagnostic for certain diseases. Make sure you have a look at the ribs and the throat.

So that can be also a sign of trauma. So circulatory, blood, and if you can get some blood for serology, that is useful. It doesn't matter if it's clotted.

Heart, is the heart looking normal in size and shape? Is there fluid around it? Is there any evidence of bacterial involvement such as endocarditis or pericarditis?

Is the myocardium normal colour or has it got pale lesions which could be indicating a nutritional myopathy? Then have a look at their respiratory system. Look at the larynx, particularly in certain breeds such as Texels.

You can get this Texel throat, which, is, sort of bacterial infection which stops them from breathing, or it could be, as I said, from farmers administering bolus or wormers which have gone down the wrong way. Have a look for any effusion or inflammation. Check the lungs, look for, again, edoema, consolidation, abscess neoplasia, anything like that is useful to send off.

Moving on to the digestive tract, the, pharynx, as I said, again, that could be, showing a dosing gun injury, oesophagus oesophagus, sorry. Is that ulcerated or is there any obstructions in there? Make sure you can check it all the way along.

Have a look in the rumen. Is it full? If it's empty, why is that?

If it's full, is it, has it, has the sheep eaten something, it has, it shouldn't have, such as, ewe leaves, these can be really deadly. Have the sheep got, you know, escaped and eaten things they shouldn't have done? You can check the pH if you've got some pH sticks.

Have a look at the Admasum, particularly if it's a lamb, have they taken on any milk? What is the thickness? Is there any amassitis in there?

Have a look at the intestine, have a look, you know, all along it if you can for any areas of inflammation, necrosis, or torsion or neoplasia, interserception in lambs is also can be, common. If you can take some of the contents for worm counts, again, that's really useful. This is one of the most common causes of death in sheep, is, worms.

Ial contents useful for clostridial toxins, as I've said, so try and get some of those. The liver, if you can see some fluke in there, do check the bile ducts, or black disease, which is a clostridial disease. Check for pale areas surrounded by dark ring, take some samples to confirm colour changes or fo necrosis, and you can take samples for some vitamins and minerals as well.

Going, further down, urinary system, check the bladder, you know, in males, they, can get calculi, and in females as well, but in males can be, blocking the, urinary tract, take some urine, maybe test it for glucose and bacteria. Kidneys. If they've, sort of overdosed on copper or lead, sometimes they can be a different colour, particularly with copper, or you can take samples for testing.

Again, you can look for Neoplasia or calculi. And then the reproductive system, are they pregnant? Is this looking normal or abnormal?

If there is, if there has been abortions, then it's very useful to take some samples from the foetus like stomach contents, if not send the whole foetus. We tried this, is there any prolapse or prior prolapse? Have they had an assisted lambing which has been particularly difficult and could predispose to, clostridial disease?

And then if it's a male, check the scrotum as well and all the male reproductive parts. And again, the musculosis bili, so all the joints, particularly in lambs, the joint, and the muscles, discoloration could indicate, again, a sort of Clostridial like black leg disease. Central nervous system.

If you can't find anything else, and if there's any kind of neurological disease suspected, it's worth taking some brain samples. And you might see some swelling if it is a clostrial disease. So it's worth knowing how to do that.

So that's sort of quick run through of postmortem and hopefully that will be useful, but the most important thing is to have a system and stick to it and check every single part, don't miss anything. Most common causes of sudden death. So here we have some data from the labs up in the north, and, this was taken a few years ago, but I think it's still probably very representative of what we see.

So, and in many cases they actually don't reach a diagnosis, and this is generally due to the carcass being not in the right condition. So the main, most important thing is to submit fresh samples. The second most common is parasitic gastroenteritis, so worms, so yeah, if, if you're, this is really, farmers don't realise how common this is, and really should be the first thing you look for.

And coccidosis, and then we move on to the, Clostridium on pastorrella type diseases. So pulpy kidney, pastorella septicemia, pastorala pneumonia, and a bit further down you can see lamb dysentery and pleural pneumonia. So these ones highlighted in red are ones that are could be preventable with vaccination.

But yeah, you can see here there's lots of also smaller ones such as intestinal torsion, dosing and injury, plant poisoning. So a lot of these are, are seen quite regularly. Together, pastorrella and Clostridial diseases were diagnosed in, about a quarter of all lamb submissions.

And in almost all cases, in, in this, they, they looked at all these, these cases and, and asked the farmers about their vaccination schedule. And in all these cases, or nearly all of them, vaccination was either not done at all or not done properly. And I think this is really important with Clostridium pastorella vaccination.

It's, I, I think a sort of just a bog standard vaccine that everyone should do, because it's not expensive, and, it can really prevent about a quarter of the diseases that you can get here. And if they are doing it, they should do it properly. We will go into that in a bit more detail later on.

So as I said, essential to get your postmortem examination and make sure you get it done as, as quickly as possible. In a recent study, about 75% of the carcasses had autolysis. So it just shows that people are still not getting them in quick enough.

So let's look at the most common, or, you know, two of the most common causes of sudden death which are pastorella and clostridial disease. And so we'll look at pastoralla first. This is very common.

It's caused by two types of bacteria, BBSynia tree halosi, which used to be known as pastorella tree halosi, and then Mannheimula hemolytica, which used to be called pastorella hemolytica. So you will still hear the disease referred to as pastorella by farmers, and this can be slightly confusing as the bacteria now have different names, so don't let that trip you up. 16 different erovars.

There's two, sort of forms of it, pneumonic, which is basically where it just affects the lungs, and then systemic where it gets into the bloodstream and and causes systemic time, sys systemic, signs. And often you'll see it in these young and store lambs, so you'll see it in sort of well grown lambs or lambs that are growing well. It's often the, the big chunky lambs and the ones that are fast growing.

Autumn is a very common time to see it, and, lush pasture, often it, it's associated with a change of, weather, or a change in, in the animal's condition or the way it's kept. We'll look at that in a minute. So yeah, autumn is, is, is certainly the most common time that we see it.

And the bacteria unfortunately are carried by all sheep, so basically all sheep will have the bacteria in their lungs and on their tonsils and . They are there waiting, ready for any kind of gap in protection on that sheep, and then they can get in and cause disease. So it's the stress kind of precipitates it.

The bacteria then start to multiply and then they produce the toxins. The toxins get into the blood and that's what causes them to die. And that's what the lungs can look like a postmortem.

You get this very sort of heavy black, consolidated look to them. So, on this lung, what you'd want to do is take a sample where you get some of that dark lung and some of the, the pink lung in the same, in the same sample. Don't take small, small pieces.

You need a good size of piece so that the lab can diagnose it properly. I wouldn't say this is pahonemonic. If you see that lung on postmortem, I would still want you to send it off to the lab because other things can look similar.

So trigger factors, sheep are prone to stress anyway, so, life is generally quite stressful for sheep, but there are more things in their lives which can make it extra stressful. So things like moving from, the hill, if they're out on the hill having a lovely life, and then they're brought down for housing and lambing, that's pretty stressful. Movement, you know, travelling anywhere, going to the markets, sudden changes in weather.

Weaning in lambs, obviously, other diseases will bring down their immune system and predispose them to this, lambing, sudden change or increase in nutrition, handling, if they're not used to handling, you know, all these things can, can precipitate the disease and, and, and cause that stress. Oh yeah, and also deficiencies in certain, such as cobalt and selenium. And I said here, or I said earlier that we most commonly see this disease in autumn, and this is just some data from, again, lab data where they diagnose the most or pastoralosis in sort of September or October, which is, is the autumn.

So, yeah, that's the time when you need to look out for it. If you find, if the farmer finds a sort of healthy, large, growing lamb dead in the field, suddenly in autumn, particularly if there's suddenly been a weather change, I would say this disease is 100% likely nearly. So that's pastorella.

We're moving on to Clostridial. Clostridial are also bacteria, they live everywhere as well, so, they live mostly in the soil, and then as the sheep is eating, they pass through the intestinal tract. So they're always going to be exposed to this bacteria.

Some fields seem to be more prone to it than others, and farmers do often know which fields are more likely to have it in there because they will have had animals come down with the disease in the past. They can survive in a spore stage, which is very resistant and lasts for ages. So even if they took the sheep off a certain field and didn't put them on that field for 3 years or so, the, the spores could still be in in the soil quite happily.

And the bacteria cause toxins, so it's not the bacteria that cause the animals to die, it's the toxins, and the toxins are, are very quickly released into the bloodstream or into the local area and and cause these signs. And again it's it's sort of set off by these trigger factors. And stress being one of them, and again, they often do die within 24 hours very quickly.

And there's a different, a whole range of bacteria, a whole range of clostridial bacteria which can cause these diseases. So here is the list. I wouldn't think that you need to know all the names.

I certainly don't, but it's just worth being aware that you have all these different diseases and, they are caused by different types of Clostridial bacteria. And also some vaccines cover some of them, not many vaccines cover all of them. So even if a farmer is vaccinating with one vaccine.

They may still die of one of these that isn't covered by that vaccine. So this is why it's worth getting, even if the animals are vaccinated, it's worth getting those postmortem samples and getting and finding out what exactly which clostrid or bacteria has caused that sign, because if they're using one vaccine and it's not caused by that, you can then suggest them to use a different vaccine which will actually cover that particular bacteria. And also that stops the farmers from losing faith in the vaccine, which is, you know, something we don't want.

So, these green ones are covered by Oviva P. These ones, of course, are covered by Heptova P. And then there's another vaccine called Bravoxin 10, which covers all of them.

So, do you know your vaccines. I don't have time. I will go into them a little bit later, but I don't have time to go into all of them in big detail.

But it's very important to make sure you know your vaccines, know what's available and what they cover, because the farmers will probably not. So they'll be looking to you for advice on these. It's just a little bit on lamb dysentery because this is one of the most common.

You get these lambs sort of scouring, tucked up, abdominal pain, possibly collapsing, looking stiff in the back end, then convulsions and death. So this is a very common cause of disease in lambs, and the first thing I would ask if I saw these signs is, is the ewe vaccinated? Because if the ewe is vaccinated, the protection will go in her colostrum to the lamb, and they, they won't, they really won't die of this.

In vaccinated ewes, you don't see, you don't see this problem in lambs. So. So different clostridial diseases freshen the lambs at different ages.

And so this can help you with your diagnosis. If you have a lamb dying at one week of age, it's much more likely to be lamb dysentery. If you're getting them a bit older, it could be pulpy kidney.

If you're getting them a bit older, it could be something like braxy or black disease, or struck as they get even older. The tetanus can hit them at any time. So it can help you with your diagnosis, but again, I, I still would be keen to get a, a lab, a proper lab diagnosis.

And don't just clostridial disease isn't just a disease of lambs, you know, adult sheep can also die from this disease, so I, I wouldn't rule it out if I had an adult sheep found dead. Black leg as well. So can you treat these diseases?

The, the short answer is no. The, they are caused by bacteria, but, the antibiotics and antibiotics will kill those bacteria, but normally by the time you've got the antibiotics into the sheep, the sheep have already died, or it's too late. So, it won't do much to try and jab them with antibiotics.

Unfortunately, this disease is not easily treated. So the best thing you can do is prevention is better than cure, as we always say, and really you can do a bit in terms of management. So for Clostridial disease, certain fields are linked to, outbreaks, and, so you can try and avoid these fields.

Hygiene will help with things like, blocking and castrating if your hygiene is good. Controlling parasites such as fluke will mean you're less likely to get, plaques disease of the liver. Pastorella, you can try and manage your stress and, you know, try and keep the animals' lives as stress free as possible, but they are sheep and that's quite difficult.

So really, vaccination is the most sort of cost effective and, least time consuming probably way of doing this. You know, it gives you, just gives you that peace of mind. No vaccine is good enough to 100% prevent every single disease.

And, Clostrid on Patrella vaccination is. I would say very effective. I would say about, you know, 90, 95% effective.

So if you're gonna give her a flock of 500 sheep Clostridium on Patrella vaccine, they're gonna be very strongly, very good protection is going to be given to them. Occasionally, if there is a very high challenge in that flock, you may still get a couple. From pastorella, but it is much less than you would have if they hadn't vaccinated.

So it's about, it's slightly about managing expectations as well with these vaccines. They're very good. They are, nothing is going to be 100%, you know, stopping disease altogether, because I think that's impossible.

Cool. So, what do we have available? These are just a few, examples.

So the most common one that's often used is heptoact P, which covers 7 Clostridials and pastoral and this is the most, most farmers do use this, this is sort of the bog standard one, which, I tend to recommend to everybody, because I think it's just, you know, it will cover most of them, and it also covers your pastorella. And that's given to ewes and lambs, so mostly ewes that are gonna give, give birth to their own lambs, and then lambs that they're gonna keep, on for breeding. Oviva P contains 5 clot strains and pastureella, and that is for growing lambs only.

So the only reason you would give this vaccine is for growing lambs, not for pregnant sheep. Provoxin 10 covers 10 clostridium strains, but no pastorella. So this vaccine I would only use in, farms where I, they've diagnosed a clostridial disease that is not covered by Heptova, because then you'll also probably need to add in a pasturella such as Ovipast, to cover that, because I would not like to risk my flock by not giving them a pastureella vaccine.

So those are some examples of, of the vaccines that can be used. And as I said before, they're not too expensive and if you give them properly, they will do a very good job of preventing these diseases. And this is just a to reiterate that it's very important and some, a lot of farmers still don't really understand this.

These are dead or inactivated vaccines, essentially, so 22 doses as needed when they're first given. So you give one dose, you give the second dose 4 to 6 weeks apart. This, red line with the yellow underneath shows the level of protection that you get.

And then this starts to then sort of decrease throughout the year. And then you give your one booster, to the ewes before they lamb, 4 to 6 weeks pre lambing, and then this will give their, their protection also to the ewes, but also to the lambs through the colostrum. And so this is a really crucial point, that many farmers don't necessarily get right.

Colossum is so important, for many reasons, like which I can't have time to go into, but, particularly because it gives us passive immunity to the lambs. The lamb takes on the colostrum, it gets the antibodies from that, and that will give it some protection against the diseases that it will face in the first few days and weeks of life. Unlike, dogs and cats and horses and human babies, no antibodies pass through the placenta of the sheep.

So the lamb has no protection at all until it takes on that colostrum. And then, that's that will really give it some protection until you can vaccinate the lambs themselves, and they can be vaccinated from about 3 weeks of age. So here we have another graph just showing the lambs.

So, you, you have your lamb age sort of along the bottom, and it's got its passive protection against pastorella, which lasts about 3 weeks if it's had colostrum from vaccinated you. Passive protection against Clostridia, which lasts a bit longer. So you really want to get your vaccine into the lamb, Heptova P, ideally, from free.

Weeks of age, you get your second dose in 4 to 6 weeks later, and then you, you really minimise the, the, the thing you don't want is this trough, between the passive protection and the protection, because this is when they're most, most at risk of getting disease in this kind of immunity trough here. So, the, the, the sooner you can get your, your protection on board, the better, and the less lambs will be lost. And then the lambs can have their boosters every 66 months or a year later, depending on the system.

So nearly done. Just wanted to make a point about the importance of technique. A lot of farmers, you know, they vaccinate every year, sometimes they can get a bit lazy, and these vaccines often don't have very good or any preservative in them.

And so if they're not. Stored and given correctly, they won't work so well or at all. And then the farmer will lose faith in the vaccine and might even stop doing it altogether.

So the most important things you can reiterate to farmers are the sheep need to be clean and dry, don't see vaccinating into a sort of muddy neck or anything like that. Do handle them carefully. We know that stress is not a good thing for sheep, so, do handle them carefully and make sure they're not stressed.

Shake the bottle to mix it well before using. Using a sterematic vaccinator such as the one in the picture means that the needle is actually sterilised between every jab, so they're not then contaminating the bottle between vaccines. Try not to use or don't use other treatments at the same time as vaccinating.

The animal's immune system can really only cope with several things at once, or, you know, the less you have to hit it with at the same time, the better. So if you can vaccinate without doing other other things at the same time, that's very good. And, just to make sure the sheep are healthy, if you're vaccinating unhealthy sheep, their immune system will be too challenged and won't be able to, deal with that.

It won't be able to sort of produce the required immun immunity that is needed to respond to that vaccine. So we've just come to the end of the talk and if you're really interested in this and you want to learn a bit more, we have our MSD Animal Health hub, which the website is here. You have to sign up the first time you, you do it, but it's got loads of really good stuff on there.

There's some how to vaccinate videos. There's some lamb what we call our lamb tool kit, which has got some really useful, things for helping farmers when they're lambing and recording data. So if you are interested in sheep and, and lambs and, helping your farmers, then, then do visit this and sign up and there's some good CPD on there as well.

So thank you very much for listening and I really hope you found this talk useful and and interesting.