Investigating icterus (jaundice) in pigs

In this episode, APHA's Pig Expert Group leads Claire Scott and Susanna Williamson discuss completion of a diagnostic investigation into a case of icterus (jaundice) in weaned pigs.

Please note that this podcast includes pathological descriptions of animal disease which some listeners may find upsetting. 

This episode was recorded in May 2026.

Useful links: 

1. You can read more about investigation of icterus through our new information note. 
2. This case was also described, with a picture, in the disease surveillance in England and Wales (July 2024) report which is published in the Vet Record. 
3. A case of leptospirosis where unusual antibodies were detected is described on page 5 of the quarter 1 2017 pig disease surveillance report. 
4. Read further information on leptospirosis in humans. 
5. Find out how vets can submit farm animals in England and Wales for a post-mortem examination and check if the submission is eligible for free carcase collection. 
6. Find your nearest Veterinary Investigation Centre (VIC) or surveillance pathology partner. 
7. Find out how vets can submit samples from farm animals in England and Wales for diagnostic submissions. 
8. Go to AHDB's website for pig farm biosecurity recommendations. 

 © Crown copyright 2026

Transcript

SPEAKER_00 0:00

Welcome to the third podcast in this series where we talk all about animal diagnostic investigations completed here at the Animal and Plant Health Agency. I'm Claire and I lead the APHA's Pig Expert Group. And today I'm absolutely thrilled to have the wonderful Susanna Williamson with me today to talk us through an interesting investigation into icterus and deaths in weaned pigs. Before we start, Susanna, can I ask you to introduce yourself to our podcast listeners?

SPEAKER_01 0:27

For sure, Claire, and thanks very much for having me. So I'm the former Pig Expert Group lead, also based at Bury St. Edmunds here in Suffolk, was a general VIO for a long time, and then in 2014 became officially became the Pig Expert Group lead then. So that's what I've been doing until you you came and are doing a fantastic job, Claire.

SPEAKER_00 0:47

Oh, thank you. I can't tell you how amazing it has been to learn from your wealth of experience as a veteran investigation officer since the early 2000s and um and and previously holding this post so successfully. So I've been incredibly lucky. So Susanna, can you kick us off then with this discussion, which I'm really excited to have with you, by telling us a bit about the background of this case?

SPEAKER_01 1:08

Yes, well, this was um a case which came to the Berry St. Edmunds VI Centre, and the VIO got a call from the Herd Vet who had they'd seen a bit of a problem with the odd yellow pig in wieners coming in from an outdoor wheeling unit into a unit with um indoor straw yards, and it hadn't been much of a problem, but the latest batch had had more affected than previously, and that's what prompted the call. So they had about 2% or so affected, with um yellow being yellow, but also some deaths. They also did describe that some of them weren't particularly well grown, but wasting wasn't a widespread feature, um, and some lethargy was seen in the affected pigs. The vet also said background details. They said about vaccination, which was carried out at Weening, they were vaccinated for PCV2, mycoplasma, high pneumonia, and live PERS vaccine. No problems that they knew of with any of those things. Great stuff.

SPEAKER_00 2:03

So from this discussion, I take it that a decision was made between the submitting vet for this case and one of our veterinary investigation officers to submit some pigs to the Veterinary Investigation Centre for post-mortem examination. So um we'll put the links in the show notes for how VETS can do this. So how VETS can submit carcasses or samples to one of APHA's veteran investigation centres or surveillance pathology partners. And we also go through this in our first episode if listeners would like to hear more about that. So, Susanna, can you can you tell us about what the VIO found at post-mortem examination in this case?

SPEAKER_01 2:39

Yeah, sure. So they had two suitable cases of freshly dead pigs, just over four weeks old. So they've been recently weaned. Um, and they were brought into the Berry St. Ebbins VI Centre. Um, they weighed them, obviously, um, not in particularly poor condition, but they did sort of see from the outside of the pigs straight away that they were yellow. Um, and that was from the skin and also the sclera um around the eye. That's a really good place to look in pigs. Often, if you look at the oral mucosa to look for yellow, it can be quite hard. It's a thick sort of thicker skin, and it can be quite hard to decide whether it is um is yellow or not. It can actually just look white or pale pink, um, even in a jaundice pig, unless it's severely jaundice. So the really good place to look in pigs is around the eye, the ocular mucosa, the conjunctiva, and the sclera, and and then the um vaginal mucosa as well is a good the vulva of is a good place to look. And the skin itself, of course, in in pigs which aren't coloured, haven't got any pigmented skin.

SPEAKER_00 3:36

Great, that's really helpful. And we've actually um we've we've written about this case in a previous VET record, and we we put a photo in that publication. So we'll pop a link to that in the show notes so that our listeners can see in this case just how just how marked that icterus was. Yeah, um, as you say, it it isn't always that way, is it?

SPEAKER_01 3:54

No, not at all. And they can be quite subtle. Okay. Um, you know, it's depending on what stage of the disease they're at as well. If they're earlier on and you know they can be yes, less yellow.

SPEAKER_00 4:03

Okay, so we know that a full diagnostic post-mortem examination is important in these cases. So could you start to go through with us then what the veterinary investigation officer found?

SPEAKER_01 4:13

So once they'd opened up the pig, um, the principal things they showed in these ones was uh kidney pathology. So both of the kidneys were noticeably enlarged. Okay, and when they peeled off, and it's very important to do this, peel off the renal capsule. So the best way of doing that is to cut the kidney into left and right halves, um, and then peel the renal capsule off both halves, and then you can see the colour, any whether there's any particiation, pale blotches, any change in the colour of the kidney, you'll be you'll be able to see then, um, which you won't necessarily be able to if you don't take that kidney kidney capsule off. Um so they noticed that they had pale foci and pinpoint hemorrhages over the renal cortices, so on the outside of the kidneys, but also on the cut surface, um, they saw that at the junction of the cortex with the medulla, there was marked markedly red, noticeably red, and it showed up a bit because the pay the kids were sort of slightly pale, so it actually showed up quite nicely. So they were obviously abnormal. And the VIO wasn't able to say immediately at that point, I think it's this, although they had some suspicions, but they certainly could tell that there was something wrong with the kidneys and describe that really nicely. Because one of the most important things when you're doing a post-mortem, if you're not sure what's going on, is to accumulate the lesions that you're seeing and note them down ideally, because it's amazing how quickly one can forget walking away from the farm or wherever, but accumulate the signs, the lesions that you're seeing, um, and just be able to describe them to someone else accurately, because then you can reflect on them yourself and you can also get a colleague to go through them with you and think about what differentials you might be needing to consider.

SPEAKER_00 5:50

Yeah, totally. And I guess that's where photos can be really helpful as well. And um, particularly in the on-farm environment, sometimes it's helpful to ask the client to take a photo of the pathology that's being demonstrated. So back to our case then. Um you've got icterus at the sclera and you've got the kidney pathology that you've described. Um, was there anything else to note at post-mortem examination?

SPEAKER_01 6:10

Yes, so the fat itself was yellow. Okay. Um the subcon and the sub umcutus, so the subcutaneous tissues looked yellow. Um, surprisingly, the the there wasn't much going on, you know, in in a in a jaundice pig, you always look at the liver because um the liver is a root of much of the uh many of the causes of jaundice. But in fact, the the liver wasn't particularly abnormal in this pig. But um, because of the deaths and because um mortality, one must also bear in mind that you could have a notifiable disease going on. The VI was went through lymph nodes, spleen, um, and all other organs to make sure that there wasn't any other lesions that they should should raise concern about notifiable disease, and they didn't. So the spleen was normal, um, lymph nodes weren't enlarged and there wasn't anything else worrying, no pneumonia or anything like that.

SPEAKER_00 6:58

Great. So in this case, the veterinary investigation officer wasn't suspicious of swine fevers because of both the epidemiological findings not quite matching and also the um post-mortem examination findings that you've described. So that means that the veterinary investigation officer could proceed with their investigation rather than uh needing to report as um suspect notifiable disease to our APHA field colleagues, which would then lead to them completing um an official investigation rather than us. Um and we'll pop links in the show notes as always as to how uh listeners to the podcast can report suspicion of notifiable disease if relevant. Moving on then, can you tell us, Susan, about the uh final post-mortem examination findings for this case?

SPEAKER_01 7:43

The stomachs were empty, so that tells you either they hadn't been fed or they hadn't been eating. And given that it was a wiener site, a commercial wiener site, one would expect them to have had ad lib food. So the likelihood is for these pigs, and especially with the clinical signs they described of lethargy and so on, that they hadn't been eating. And it's actually useful to look in the stomach, even if you don't think you've got a gastrointestinal problem, it's always look worth looking at the gastrointestinal tracts because it does tell you some things about the pig, even if it's systemic disease it's suffering from. So, how what's in the stomach? Um, what does the stomach mucosa look like? Is it reddened, is it ulcerated? And then um, when you're looking further down the gastrointestinal tract, it's always worth looking at pairs' patches to see if they're enlarged and whether there's any abnormalities of the mesenteric lymph nodes, whether they're enlarged.

SPEAKER_00 8:32

Great, that's super helpful and even more useful nuggets for our listeners. Um, can we go through then the differentials that you would have in mind for this case and kind of more generally for icterus in a pig, and whether any of your findings up to this point are helpful to diagnose the cause in this case?

SPEAKER_01 8:50

Sure. One of those differentials for jaundice is septicemia. It's not something we commonly see in septicemia. We obviously see a lot of septicemic pigs with things like Strepsuois and GLACs. Um, but amongst those causes of septicemia in this age of pig, you can get erosipolis. And occasionally we have seen jaundice pigs with erosipolis. Um, and that's we think it is probably because of intravascular hemolysis occurring, um, and then the liver not dealing with that. And so setting up cultures from good systemic sites for um septicemia is a really good idea. So good sites to choose. Um, well, in the lab, we would in the PM room, we'd always choose meninges, because it always would pick up a meningitis case as well. So that's obviously a bit harder to do when you're in the field, but we would choose meninges as a site, and liver is good, uh spleen, and then lung.

SPEAKER_00 9:43

So if you've got any tips in terms of how um that's working in the field might take those.

SPEAKER_01 9:48

Yes, it's always harder in the field, and we would do it different differently in the PM room because uh we can sear the surface with a with a heated um object, whereas you can't do that in the field. So in the field, you're really down to trying to keep the PM site as clean as you can. And then when you come to deciding, right, I'm going to take a swab from the liver, um, don't swab the liver capsule on the outside, A, because it won't be swabbing the substance, and B because it's the most likely place to be contaminated at that point. But ideally, if you have got a sterile scalpel with which you can cut into the liver, and then before you touch that liver surface, rub vigorously a charcoal swab on that surface and then put it back into its container, the swab back into its container without touching anything else.

SPEAKER_00 10:33

Um it's save so it's having um so so doing your post-morsem examination and then having a fresh, clean scalpel to make your cuts, the cultures, incisions into say the liver, um, and then you're swabbing the cut surface, which should hopefully not be contaminated. Yes.

SPEAKER_01 10:53

I mean that I don't expect that vets are going to want to carry, you know, five different scalpels with which to do that. So maybe start with your start with your liver and then then maybe do your your lung and then your spleen or or spleen and then lung and accept that um your sterile scalpel is not sterile the second time you use it, but at least you know if it's not visibly contaminated and you if and doesn't have fecal contamination, you're being as clean as you can. So try and be as aseptic as possible. I would always open the the GI tract last. Yeah. And so if you are thinking I want to do cultures, take those swabs before you've gone near the GI tract because otherwise it's going to be so much harder for you to keep contamination away. Okay, great.

SPEAKER_00 11:37

I've sent you off on a tangent there, so I'll bring you back on. So you have talked through then your um first differential for uh jaundic pigs, which was septicemia. Can I ask you um to talk through your others?

SPEAKER_01 11:50

Another one to consider um is porcine secovirus two hepatitis, which is a recognized manifestation of PCV2. And it's really interesting because we have seen PCV2 hepatitis affecting entire litters of um unvaccinated pigs, mainly seeing it in small herds, which are the most likely to be unvaccinated, and sometimes um they've been, you know, four or five weeks old, so this age, that young, and dying with um acutely enlarged um livers. But there, the liver is visibly affected, and yes, the kidneys might be a bit affected, but it's the main pathology is in the liver, it's enlarged. You can see um mottling in it, and when you cut the surface, there's also the bile ducts are actually quite full of bile as well. Okay, so that needs histopathology to confirm it, and you do send liver and lymph node. So, again, from these cases, I would always be fixing main organs anyway, certainly include the liver and the kidney and lymph node and spleen. I would be fixing small portions, one centimetre cubed at large, that the largest, um, into formulin one in ten. If you get in the habit of doing that, then you're not going to miss out on an organ that you wish you'd had put in. So try and put everything in, even even heart, um uh in in in cases that you're post-morteming.

SPEAKER_00 13:08

Yeah, and so on that on the PCV2 hepatitis, do you see the large subinguinal lymphnose with those? Is that it or not? Um not necessarily.

SPEAKER_01 13:18

Yes, but it isn't not it isn't necessarily a big feature.

SPEAKER_00 13:20

No, it's the liver that is the hepatitis.

SPEAKER_01 13:23

It's the hepatitis that is is the hallmark. Um, we do, but you are right that we sometimes see um hepat PCV2 hepatitis um less uh dramatically as part of a wider spectrum of pathology in postnate post-weaned pigs. So I've seen outbreaks of PCV2 where the vaccination regime went wrong, basically. Um so you've got PCV2 where you don't expect it in a vaccinated herd, which is maybe where you get more variable pathology, where the pigs coming in are all affected, but they're not all affected with hepatitis. So let's say you have three pigs submitted, you might have one with hepatitis and jaundice, another with um enlarged lymph nodes and blotchy white kidneys, um, and another with gastroaculceration and enlarged lymph nodes. And they are all PCV2, but um only one of them has manifested as hepatitis. And we have seen that over the years, we've seen occasional outbreaks like that.

SPEAKER_00 14:17

Wow, fascinating. Sounds like a great case for a feature podcast. Um and then moving on, then to any other differentials for um this clinical presentation.

SPEAKER_01 14:28

Yeah, so the VIA was actually most suspicious about leptosporosis in this in this case, um, largely because they'd heard about cases before where there was jaundice postnatally and the kidneys were more affected than the liver. So, for that, the most important thing to get is tissues, tissues for PCR. So that's kidney um andor liver, but you went for kidney. That was the most affected organ, and also taking tissues, as I said, for histopathology, just in case the PCR for some reason didn't work, it you might be able to um look using histopathology on the kidney and then using silver stains occasionally. Histopathologists have been able to visualize leptospira um in the in the kidney tubules.

SPEAKER_00 15:14

Great. So um what was the last differential then that you were going to discuss as uh one of the most important differentials for ictaris in pigs?

SPEAKER_01 15:24

Maybe I should have mentioned it after we mentioned talked about the PCV2 because it's another one where you get dramatic lesions in the liver, and that is coal tar toxicity, which causes liver enlargement, liver mottling, and often you'll see ascites and edema of the mesocolon and edema of the intestinal mesentery in the abdomen.

SPEAKER_00 15:42

Right.

SPEAKER_01 15:43

But the pigs are really sick and dying. Um the liver really does look abnormal, you wouldn't overlook it. The clinical signs alone, although the pigs are apebrile, could make a vet worry about um swine fevers. And we had have had people ringing VIOs concerned about that, but the pigs have been afebrile, and the very particular pathology, hepatic pathology, steers you away from swine fevers. And so the taking histopathology of the liver, doing that on the liver is most important first line of investigation for that. Um, but the histopathology on its own doesn't tell you it's coal tar toxicity because that can look like hepatosis dietetica, which will also cause pigs to drop dead, but they tend not to have jaundice because they die quickly. Um, so the histopathology alone isn't going to tell you it's coal tar poisoning. Um, it's really important that the environment of the pigs is looked at and the history of the field or accommodation is investigated to see what possible source of coal tar could be. It's going to be something roof felt, creosote, um, clay pigeons if they're outdoors, asphalt, tarmac, anything um which might bitumen, anything like that. Pigs actually quite find it apparently quite aromatic and and can seek it out and chew it and ingest it. And I think that's happened with roof felt where it's torn off a roof into a field, and pigs have gone and investigated and eaten it and then died. So um, yeah, it's not a nice one. Um and and like I said, dramatic and quite different from these pigs in the is the hepatic pathology, the liver pathology that really um is is the significant finding.

SPEAKER_00 17:21

Great stuff. Okay, so we uh have collected then our swabs for culture for um septimia, kidney for PCR for leptospira, um, and then a selection of tissues for histopathology for our PCB2 associated disease and also our coal tile toxicity. You've said that if you were to hang your hat on a diagnosis here, you'd be thinking about leptospirosis really. Um, and so can you just summarise for our listeners then what specifically about this case um leads you towards that diagnosis rather than the others? So I'm thinking the lack of liver pathology being quite important for that.

SPEAKER_01 18:02

Yes, that is that is important. Um, the degree of jaundice, I think, um whilst you can septicemia, and I'm talking really erosipolis, because I don't think we've seen septicemia, uh sorry, jaundice with any other septicemia. Okay. Um, but with erosipolis, when we've seen that, it's been quite subtle. Um, so if you're getting a good um impression from the vet who's in the farmer who's seen the pigs, that yellowness is a big feature, then and and this is yellowness in pigs which are still walking around, that's unlikely to be septicemia. So that's one clue and turn it to it which would steer you away from septicemia. And yet, like you say, the liver pathology in PCV2, hepatitis and coal tar um would equally um steer you away from from those, that the lack of hepatic pathology in the lepto cases. I think if you did microscopy, so if you did histopathology in the livers, there would be pathology, but there isn't that it's not striking when you look at the pigs. So I'm not saying the livers are normal, but they're not the most abnormal thing about the pig. And I think quite consistently, consistently in our postnatal leptosporosis cases, it's been the kidneys which have shown that pathology.

SPEAKER_00 19:09

Right.

SPEAKER_01 19:09

Um, the one that I should mention, there is another cause of jaundice which equally um might leave the pigs apebrile walking around um and sometimes dying, would be Mycoplasma suiss. If you look at the textbooks, that is um that causes hemolysis of red blood cells, and that's it's a pre-hepatic cause of jaundice, but we very rarely see it, and we very rarely diagnose it. Um, it's quite meant to be quite ubiquitous, and there's some quite nice papers out there. Um, we have diagnosed it in in the past, but I I I think its rareness means I would we wouldn't put it at the top of the list, but in order to cover for that, we would send you can send spleen for PCR, specifically asking for Mycoplasma PSUIS, and certainly the VIO would have collected spleen and kept that stored just in case that was needed. The annoying thing is that um it's the spleen is actually less sensitive than EDTA blood from a live affected pigs for detecting the pathogen, and it wouldn't be that easy to diagnose from um looking by histopathology. Okay. So if you had live pigs um affected, getting EDTA blood off those for Mycoplasma PSUIS is is the way to go. And we do offer if you do a um bloods, EDTA bloods from three pigs, we can pull them and do them under one test code charge for mycoplasma. But it's probably best to speak to a VIO about that because you'd need to sort of ask for it specifically.

SPEAKER_00 20:33

Sounds good. And yeah, like like all our cases, these are this is our kind of initial testing to rule out the common things, but actually, while we're here is to investigate novels. So testing these samples initially, but having um backup samples to then look at if if that testing doesn't come to anything.

SPEAKER_01 20:49

Yes, and I think this was a nice case for the VIO to decide on that testing because, like you say, they take a lot more samples than they process. Um as a you know, it's always good to have those samples as backup, but we don't want to go to unnecessary expense um and use up resources where they're not needed. So cultures would be the first line because you don't want to delay on those. And then once 20 after 24 hours fixation, those tissues, and I would say that it's highly likely they would have sent um lymph node, liver, and kidney. Those would be done in order to investigate it with um the leptosporosis, but also that would rule out PCB2 as well. Great stuff. So culture.

SPEAKER_00 21:25

Yeah, yes, of course, yeah. Um what was found in this case then?

SPEAKER_01 21:28

Yeah, so that we have a pathogenic leptospira PCR, and that came back positive on the kidney on both of the pigs. And that is confirmation of a diagnosis. Um, it's not an organism you expect to find in subclinically affecting um pigs in their in their kidneys. Um, so it's that's for us, um, fulfills the case criterion. Um they did actually do uh histopathology. Um you just said about new and emerging diseases. Often the VOs will go a little bit further just to make sure there's nothing else going on. And um also sometimes if it's the first time you've seen something. It's nice to know the pathology behind what you're actually seeing grossly. Um, and in this pig, they found that there was a chronic supprative and necrotizing tubular interstitial nephritis, so definitely a lot of damage being done by the leptospires. Um, there's no there was no um silver staining done because they had a positive ID of the leptospir already.

SPEAKER_00 22:20

Great. Okay, let's just take a little step back then. So can you tell us a bit more about leptospirosis in pigs and what um is this the only clinical presentation, or do we see others and and how do we um consider leptospira to affect and leptospirosis to to affect pigs?

SPEAKER_01 22:39

Well, the the main manifestations we see at APHA are that they're in two separate types of disease. One is reproductive, and that tends to be late abortions, uh, mummies stillbirths, so it can be at term as well. Um, often progressive, it seems to be progressive deaths, but it can sometimes they're they're all one stage, dying all at one stage, so that's variable, but it can cause what looks like SMEDI when the livters delivered. The sow's may or may not show things still birth.

SPEAKER_00 23:08

Sorry, yes, go on. Ebryonic death and infertility, brilliant.

SPEAKER_01 23:11

Correct, yes. Um, and that alone, I mean, that could be caused by a multitude of things, but lepto is is in there as one of the differentials. Um, the sows aren't necessarily ill with that reproductive form, um, but they can be. And I think that is probably down to which leptos is causing the disease. Um, and if it's once something like leptospira ictero hemorrhagia, it may be more likely to cause illness in the sounds. The rats the the reproductive form, and then the postnatal um leptosporosis, we tend to see around uh either I would say peri-weaning. It doesn't we I haven't seen it in finishers, and I don't think we've diagnosed it in finishers or even late growers. It's always been in the perhaps the week before weaning to the two weeks after weaning. Whether that's because of maternal antibody waning at that point, right? Um, not sure, but that's one possibility. No, one of the consistent features we've um seen in the postnatal leptospirosis cases is that when the VIO and the vet dig down, that there's a high rodent population on the farm where the pigs are affected. Okay. And that's that's um that really goes along with the most likely cerevars which are co causing the disease, which are most likely to be the rodent-associated ones like icterohemorrhaggy Copenhagen. Um, and you you know the vial disease that's caused in humans, the icterohemorrhaggy, that's the one. So um there's always a zoonotic a message about the potential for zoonotic infection when these cases are diagnosed or suspected.

SPEAKER_00 24:39

Okay, so you've mentioned that there are different cerovars of leptospira that, and it sounds like different cerovars are um mainly affecting particular species of animal.

SPEAKER_01 24:51

Yes, that's right. So on the whole, most most um of the cerevars have a particular animal or group of animals where um they could form a reservoir. And for example, um ictorohamorrhagy, which I've just mentioned, uh, would be rodents, rats, and mice. Um harjo, leptoharjo, which any of the cattle vets would know well, is um a cattle cattle reservoir. Then there's lots and lots of um wildlife reservoirs for things like Leptospara mozd and um canicola, things like that. So each of those um will have a place where they uh exist likely subclinically and then can spill out into other other animals. In pigs, uh they're a reservoir for brattis lava, but they're not the only species to be infected by brassus lava, and there's um quite a few wildlife reservoirs as well, and hedgehogs have always been mentioned, but they they are also not the only one. So it is um because of that, it can be really useful to know which leptospira is infecting pigs, whether you're seeing the um reproductive form or the postnatal form, because um A, we want to know whether we've got an exotic cerevar that we haven't seen before in the country, and there are some. Um, secondly, it might help you identify a source of infection to pigs. So we have had in the past a case of um reproductive leptospirosis caused by harjo where pigs were put in um old cattle buildings and became infected. So the pigs themselves weren't going to sustain that infection. Um whereas if it had been um Bratislava, then it's highly likely they would stay sustain the infection. So that tells you something about a the likely source and b how likely it is to persist in the pigs. Yeah, and the other useful thing about knowing the cerovar is whether in uh breeding pigs in particular you'd want to use a vaccine to control it. If you're having lot long-term problems, ongoing problems, is it worth using a vaccine? And then you want to know what the cerovar is because there's no point in using vaccination if the cerovar isn't in there. Most of the um well, there's not many different vaccines available for pigs, but those that are available tend to be multi-cirovar, so they contain, you know, five, six cerovars, um, and they're the most common ones to infect pigs. So that's another reason you might want to know. Of course, yeah. And of course, the zoonotic risk, whilst we should assume that all leptospara are potentially zoonotic, um, there are some which would cause nastier disease in humans than others. And I think you know, every most people have heard of Viles disease, which is the one that um people working in water and getting exposed to rodent urine can get occasionally, and and waterways and people, you know, canoeists, people like that get get infected.

SPEAKER_00 27:33

Got it. Okay, so um that was really helpful to hear why it's important for us to know which cerovar is implicated. So, and and so you mentioned how our PCR is for um pathogenic leptospira as as a whole, so doesn't differentiate. What can we do then to try and um ascertain the the cerebral?

SPEAKER_01 27:55

In well, if if in an ideal world, I'll say first, in an ideal world, we would culture from from the affected pigs before they were treated. But unfortunately, culture takes a good six months, it's very prone to contamination, it's very labour-intensive, technically demanding. Very few places do it. We have got people at APHA who who can culture, but it's it's something which is very difficult to do, and we would reserve it for particular situations. So the prime method we use is serology. So in these pigs, um, we would because they they were dead, so we couldn't get serum from them, um, from live pigs which had recovered, we would offer to the vet to take 10 up to 10 bloods from recently affected um pigs in the same cohort. If they weren't sure how recently affected they were, then anything that was yellow, because the antibody response that's detected by the test we use it mainly detects IgM. So with within the seven days or so of being infected, that comes up quite quickly, the teeth rise quickly. Unfortunately, they also drop quickly. So if you're waiting a couple of months before doing that that serology, you might well miss high teeth. So getting bloods off recently affected and recovered pigs is ideal. Great. One of the problems is as you can imagine, five-week-old pigs or so have maternal antibody. Yeah, and that can complicate the interpretation of the teeth. So it's not always successful. We can't always point at the results and say for sure it's that, but we have been able to in in some cases.

SPEAKER_00 29:29

Great. Okay, so we're using the serology almost as a proxy to say, yes, there's been exposure to this cerebral, um, and and therefore, um, yeah, we've got we bled 10 pigs and they their highest heaters are to this cerebral, so we expect that that was was most likely the infecting cerovar.

SPEAKER_01 29:50

That's as good as we can get with this. And what we do is we put it through an initial screen which um tests the 19 cero that we have as six pools, so they're they're pooled into similar cerovars, and if any of those pools come positive, we then test for the individual cerovars within that pool. When we're seeing um uh jaundice pigs postnatally, and we and we've heard about high rodent populations on the farm. I think you can make a reasonable um assumption that rodent rodent leptosparas are are may well be involved in and you don't have to wait for the results of the serology before getting rid of those rodents. So you can progress some of the control measures before waiting.

SPEAKER_00 30:33

Of course, yeah, and and we know that um rodents can be implicated in in other diseases as well. So where there's a rodent issue, it would be um probably pertinent to look into that. For sure. Um that's really helpful. So actually, I I believe in this case we didn't um receive SIRA to to test, but as as you say, given the history, um it's it's likely that it it been the um rat associated one of the rats associated with Cyrovars.

SPEAKER_01 31:00

I think that would be reasonable.

SPEAKER_00 31:02

And I guess actually a a nice supporting bit of evidence would for that would be that if you controlled the rat population and then saw a reduction in cases, then perhaps that might might help your case as well. Exactly.

SPEAKER_01 31:12

I mean another bit of circumstantial evidence, which we've again we you you know it's nice to speculate about um the cases we see, but we I would say we've seen a trend of seeing the cases of postnatal um leptosporosis with jaundice in the autumn months and and um one of the reasons we wondered if that was because the road rodents are then coming in from outside where they've after harvest and it's getting cooler, uh the food food reserves out there are getting smaller, they're they're coming to get food and shelter and contacting the pigs much more.

SPEAKER_00 31:48

Um great. So is there any advice then based on this diagnosis that is pertinent for um the submissive vet to provide to their clients and to work with their clients to try to um achieve it? Sure.

SPEAKER_01 32:03

But the kind of things that are are advised and the VIO would have provided um some guidance on are firstly about rodent control, effective, you know, being prompt and effective. And what's also important with that is uh making sure that dead rodents are cleared up because they are also going to be a source of infection. And if you if you have got a high rodent population and start controlling it, there is a danger that you'll have a period of time when the pigs are actually being exposed to dead rodents. So having a you know inspection for those and getting rid of those is important, and also to know that the staff themselves are aware of the risk of the rodents and you know, good personal hygiene as always, but just emphasising that to them because infected rodents or rodent urine is equally um a risk to them as well. So that would be a highlight thing to highlight, and obviously individual pigs which are affected um can have antimicrobial treatment, and that can be, if it's given early enough, can be successful. Um, whether they decide to use group therapy is is a veterinary decision and probably better made by the the vet based on the numbers affected and and um how quickly they're dying or how quickly the the farmer is um able to inject those which they see sick, and if they're managing to do that early enough, then they can maybe stick with the injectables. I don't know of any um herds where they've vaccinated postnatal pigs to prevent jaundice. I think the scale hasn't been the scale of disease, it tends not to be big enough to merit it, and you can do more by controlling the rodents. Equally, I don't know of them vaccinating sows to promote immunity in the wieners to prevent postnatal jaundice either. But I suppose you could say that if you were vaccinating breeding cells to prevent the reproductive form, you might get a collateral benefit in the wieners, or at least in the pre-ween pigs, of protecting them against um leptospirosis at that stage as well from the maternal antibody. So the primary area that vaccination uses is in the reproductive form rather than the jaundice. So, yes, hygiene. I mean, you know, if if the bedding's really wet, that's going to promote um, and and the rodents are around, that's going to promote survival of the leptospares. So that's something which is an environmental managemental intervention where the environment may be contributing to the disease where you've got high rodent populations.

SPEAKER_00 34:26

The point that you raised around the wet straw bedding is particularly relevant because the pathogenic leptosparas can survive outside their hosts. Um they can survive but not multiply outside their hosts, especially in these wet conditions. Yeah. Um, and yeah, so so uh prevention of of direct or indirect contact with with pigs and and live or dead rodents as well as potentially other wildlife for these other cerevars. Yeah, definitely.

SPEAKER_01 34:54

I mean, it's it's difficult to control that on an outdoor unit because some of the reservoirs are things like voles and shrews, and you're I don't think you're ever going to entirely prevent contact. No. Um and it's very interesting. We have a um there's a there's a a Mozdoc slash um wildlife adapted pomona that um we've seen in pigs, outdoor pigs on smaller herds, mostly on smaller herds, but entirely in the southwest. Right. Um and I think it does relate to the wildlife reservoirs, and there it was actually we managed to isolate it on one unit, or at least the lab guys did at Weybridge, they managed to isolate it from um a shrew um and prove that it prove that it was um host for that for that lepto.

SPEAKER_00 35:35

So and that's important because of the exotic um pig adapted pomona that has been found in the States. So showing that we we haven't detected that in Great Britain. We haven't. Um but but the and so the only Pomona that we've detected is this wildlife associated one, and we can put a link in link in the show notes to the quarter report where that's where that's described, which is quite an interesting thing. Yeah, that'd be grand. Yeah. Yeah, perfect. Um, so that that's all really helpful advice. And then just for the presentation of leptosporosis with reproductive disease, I guess the a lot of the advice will be similar um around the zoonotic relevance there, but I guess importance of wearing gloves um yeah for artificial inseminations, assisted assisted farrowings.

SPEAKER_01 36:18

I think it's good to have the measures in in place before people have lepito as a issue on the farm. Because so at any time people should really be taking the precautions because you never know when that's going to flare up. Yeah. So wearing gloves when you're handling afterbirth or aborted and still more pigs, and when I don't know how much people assist with farings now, but if they do, then that's really important. And then, as you said, wearing gloves when they're assisting with AI and assisted matings. Um, they obviously you could be getting infected from either a pig or or rodent, so um, you know, both both are are are risks. So when you're cleaning buildings and things, you just be aware that you don't want things to be splashing up into your face. Um and some of the leptos spars won't cause disease in in the pigs, so you know you don't they can still be there and along with other pathogens like salmonella. So taking the precautions that everyone is is um encouraged to take on a daily basis is the way to go. But if you did get a diagnosis of lepto, then you want to emphasize um those things, particularly to the farm staff.

SPEAKER_00 37:22

Great, and of course, that in addition to all our standard biosecurity that we advise on pig units, such as using clothing and footwear dedicated to the pig unit, washing hands frequently, eating and drinking away for the pigs, and we'll put a link to HDB's website where they talk about um a lot of these pertinent measures. Um I think that's all been super helpful, and I think unless you've got anything else that's springing to mind, we're pretty much ready to start wrapping up. So I wanted you to have a think about then our kind of take-home messages for this case and what you'd like listeners to to go away with.

SPEAKER_01 37:57

So the key messages I think from this would be to remember bear in mind that those chief differentials that we mentioned if you see jaundiced pigs, um, and thinking about the what you're going to look for in the pigs, about whether they're pyrexic, the morbidity, mortality, um, how quickly they're dying, all those kind of things are going to help you. And then once you get inside the pig and you'd be able to see with what kind of pathology you've got, have you got enlarged lymph nodes? Is it mainly liver pathology, mainly kidney pathology? What else are you seeing? Um, and collating all those and so you can reflect on them later, and and then have in mind the main samples you'd like to take. So you'd want swabs for septicemia, tissues for histopathology, tissues for PCR, those are the main things. Um, yeah, then in terms of managing the problem, once you've got a diagnosis, bearing in mind that zoonotic risk and giving advice to the farm staff. Um, then it's the broad prevention and treatment strategies we've discussed, and needing being helped by knowing the cerebral. So we always offer um some free serology. Whenever we get a positive PCR for lepto, we will offer, whether it's reproductive or postnatal jaundice, we'll offer free serology in order to try and help you get that identification. It isn't always easy, um, and we don't always get the bloods in anyway, but even when we do, it's not always we don't always clinch it, but sometimes we do. And that can be very, very helpful to the vets to know where the source the source of infection, whether it's worth vaccinated and vaccinating and so on. Um, so yeah, those are the main things, Claire.

SPEAKER_00 39:28

That's covered it. And I'm thrilled to also say that you've very kindly made us an information note on investigating icterus in pigs. So basically trying to summarise the diagnostic investigation onto one A4 page. Uh so we're going to pop that onto our website and we'll also put a link to that in the show notes. All that's left to say then is our thank yous. So thank you to the submitting vet and the farmer for this case, as well as for all the previous cases of um ictoric pigs or pigs with leptosporosis that have allowed uh Susanna to build this amazing knowledge base into leptosporosis along with many other colleagues here at APHA. Um, thank you to everyone at APHA who contributed to this investigation and to similar ones. And thank you finally to you, our listeners. We'd love to hear what you think about the podcast, uh, what you'd like us to discuss in future episodes, and also your experiences of um diagnosing um pigs with ipteris or uh leptospirosis and your experiences uh preventing it or treating it. So thank you so much. Thank you, Susanna, and see you next time. That's my pleasure. Thanks, everyone. Bye.