Goat Necropsy: Why did my goat die?

Whenever a goat dies, we always want to know why. But the only way to know for sure is to get a necropsy, and that's what we're talking about in this episode.

I was convinced of the importance of necropsies after owning goats for only five years when a seemingly healthy doe suddenly started screaming and was dead an hour later. Without the necropsy, we never would have known that she had died from Tyzzer's disease, which is not normally seen in goats.

Dr. Jonathan Samuelson, Clinical Assistant Professor of Anatomic Pathology in the Veterinary Diagnostic Laboratory at the University of Illinois College of Veterinary Medicine, talks about what a necropsy is, what it can tell us, and what it can't.

We talk about gross necropsy, histopathology, electron microscopy, and other aspects of a necropsy that can tell us why our goat died about 85% of the time, according to Dr. Samuelson. But even if the necropsy can't pinpoint the exact cause of death, it can rule out causes, which can also be helpful.

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Transcript

Deborah Niemann  0:03  
For the love of goats! We are talking about everything goat. Whether you're a goat owner, a breeder, or just a fan of these wonderful creatures, we've got you covered. And now, here is Deborah Niemann.

Deborah Niemann  0:19  
Hello, everyone, and welcome to today's episode. This is a topic that I am really passionate about. If you've ever emailed me and said, "Why did my goat die?" you know that I've told you, "The only way to know for sure is to get a necropsy." And, that is what we are talking about today. We are joined by Dr. Jonathan Samuelson, a Clinical Assistant Professor of Anatomic Pathology at the Veterinary Diagnostic Laboratory in the College of Veterinary Medicine at the University of Illinois. Welcome to the show today, Dr. Samuelson!

Jonathan Samuelson  0:49  
Thank you! Very good to be here. Very excited.

Deborah Niemann  0:52  
I love this topic. And, I'm so glad I saw an article that you wrote about necropsies, and I was like, "Oh, my gosh! This would be perfect. He can talk about this on the podcast." Because I think, you know, so many people want to know why their goat died, and they're just asking everybody, like, on Facebook and stuff. And, the reality is, there's so many different possibilities. I learned very early on that there is just no way you can possibly guess—because we had a super weird situation where a goat died. And, I mean, she was just laying there, screaming bloody murder for over an hour, and then she was dead. And like, I didn't have time to do anything, really. And, I wanted to know why she died. And, it turns out she had Tyzzer's disease, which, if anybody Googles that, it's a rodent disease! Every now and then, I still check the scholarly literature and see, like, "Has somebody written about Tyzzer's in goats?" And, they haven't. Like, nobody would have ever in a million years suggested that this goat—that any goat—would die from Tyzzer's disease. The only reason we knew that was because we had a necropsy. That sold me on them right away, because it was really helpful to know that it wasn't anything that was contagious, that anybody else was gonna get, or anything like that. 

Deborah Niemann  2:12  
So, let's start at the very beginning. There are a lot of different parts to a necropsy. It's not just about cutting the goat open and seeing what you can find. But, that is kind of what a gross necropsy is. So, can you just start there? 

Jonathan Samuelson  2:26  
Yeah, sure. So, you're right, it is kind of "see what we can find." There are times when I get animals presented to me—not just goats—and the clinical history that's provided by the submitting veterinarian is limited or not present at all. So, you know, without a history, going forward without some indication of what to focus on, I call those a "see what we see necropsy," you know? 

Jonathan Samuelson  2:52  
So, the gross exam is the first part—or actually, the first part is the submission, really. And, I'm going to be comprehensive as I can. My part of the job is the necropsy, but there's been a whole series of events that have been occurring leading up to the animal dying and submission to the diagnostic lab for necropsy. So, a thorough history by the veterinarian who's submitting the case is very, very helpful, and allows us to kind of focus on specific areas or, you know, kind of spend more time in certain areas, really, because, well, our time is limited. You know, there are some days I have 15 necropsies to get through, you know? So, that's a lot of time. And, I want to go home and have dinner, you know? So, I need to move. 

Jonathan Samuelson  3:37  
So, a thorough history is, like, where we kind of start, and then, you know, once I get to my part of the job, which is the necropsy—or you can also say "autopsy." So, "autopsy" means "to see for oneself," and "necropsy" means "to see after death," right? So, we typically apply "autopsy" in human medicine and "necropsy" in veterinary medicine; they're pretty much interchangeable. It's a post-mortem examination—that's the most comprehensive, right? 

Jonathan Samuelson  4:05  
So, the gross exam, the word "gross" means kind of, like, your gross income. Like, in totality. It does not mean the gross part of the necropsy, like the repulsive part of the necropsy—although that is the best chance you have to be repulsed, is in the gross exam. And, the gross exam, you know, is very systematic, so we don't miss anything—or do our best not to miss anything. So, the gross necropsy is where we do a thorough external exam. We examine the ears; examine the oral cavity; look at the hooves; look at the skin, looking for any clues. So, like, any sort of, you know, fecal staining, you know, around the anus. Maybe this animal had diarrhea—especially if we didn't have a history going into it. We kind of look for clues like that, and then we'll proceed into the internal body cavities. And then, again, it's very, very systematic. I tend to work from the front of the animal to the back of the animal, with the exception of the brain; I always do the brain last. And, in the gross exam, we are examining gross changes. We're examining changes that we can detect with our naked eye. So, that's color changes, texture changes. Is something added? Is something missing? These are kind of the things that we're looking for. 

Jonathan Samuelson  5:22  
And, in the gross exam is also where we collect the tissues required for further testing after the gross exam. So, we usually collect a subset of fresh tissue. So, these are tissues that are being collected and kind of put in a bag and either submitted for testing right away, or being frozen for potential testing later. And then, we also collect a full set of tissues, which we fix in formalin, which is formaldehyde; it's 10% formaldehyde. And, what the formaldehyde does, is it fixes the tissue and kind of maintains that architecture, which will allow us to trim the tissues later on in the second part—that we could talk about a little bit. 

Jonathan Samuelson  6:04  
So, the goals of the gross exam are to really characterize any macroscopic—so, you know, naked-eye lesions—and collect tissues. Move forward. And, some older pathologist, or more seasoned pathologists, put a lot more weight on the gross exam. And, there are, you know, other pathologists that will not put a whole lot of diagnostic emphasis on what they find in the gross exam, because there's a lot of things that it could be. I might see that there's something going on in the lungs: They're dark red; they're wet; they exude fluid when I cut on into them. But, it might be edema; it might be hemorrhage; it might be inflammation, sometimes. So, you know, I kind of reserve judgment in the gross exam and wait for the full picture with the microscopy and any ancillary testing that I might have done at any given necropsy.

Deborah Niemann  6:58  
Okay. And so, then, once you finish the gross necropsy, what's the next step?

Jonathan Samuelson  7:03  
So, once we're done, if I have any tests that I want to run... So, I want to perform a culture to see if there's any bacteria in a given tissue. There's lots and lots of tests that are available to me, but the big ones are really the ones that revolve around infectious organisms. So, culture microbiology is really important. We have a microbiology group here in the lab that does all this work for us after the fact and cultures things. We can run certain molecular tests; there's lots of different PCRs, which can detect the molecular DNA or RNA of an infectious organism or something like that. So, that's one side of what happens afterwards, this kind of ancillary testings to detect organisms using laboratory methods. 

Jonathan Samuelson  7:53  
And then, with the fixed tissue, the tissue that was saved in formalin, we'll usually let that fix overnight, right? It takes a certain amount of time for the formalin to adequately penetrate the tissues that we've collected and fully fix them. And then, the next morning, I will come in and cut those small sections of tissue that I've collected from each organ into even smaller sections. And, that will fit into a cassette, and it's this kind of small, you know, rectangular container that we can put flat tissues in. So, we put all the tissues into these different cassettes, and then we submit it to the histology lab. And, the histology lab performs a number of chemical treatments to it, and then they mount the tissue in wax, and then they cut very, very thin sections—like, kind of paper-thin, 5-micron thick, sections. And, once they get a good section, they can lay that on the microscope slide, and then they do a couple other awesome things to it, and they stain it with some different reagents. And then, you know, we can look at the tissue microscopically and examine the cellular architecture. And, that part of the necropsy examination is called "histopathology," so examining for disease on a microscopic level. 

Jonathan Samuelson  9:16  
And, I am kind of more new school. So, a lot of my definitive diagnoses come from the histopathology exam. I like to confirm what types of cells are there. If it's an inflammatory response. I like to fully characterize cancer, if it's there, you know, and what types of cells are they? What are they doing, you know? And really, you can only do that with histopathology. And, there are some modalities that allow us to go even further. So, we can use electron microscopy to examine the ultra structure of cells, which is, we're looking at mitochondria and ribosomes and nuclear contents and stuff like that. So, that is kind of in a nut shell the whole thing, but it really relies on really good communication with the submitting veterinarian, and sometimes even the owners.

Deborah Niemann  10:10  
Okay. For many of the years I've had goats, I didn't have a local vet. And so, I've usually submitted goats directly to the university. So yeah, so then I would wind up talking to one of your vets there, and giving them the history and everything. So, how do you know, like, which direction to go? Because, like you said, there's so many different possibilities. What kind of guides you in terms of knowing, like, which tests to do or not do?

Jonathan Samuelson  10:39  
Yeah, that's a great question. And, I try to utilize everything that's available to me. You know, everything from the history and my communications with the referring veterinarian, to what I see on the gross exam. You know, as far as goats go, they're production animals. So, a lot of the times, the things that we're seeing in production animals are kind of respiratory disease, or intestinal disease... There's lots of other things, and that's not inclusive at all. But, those are the things that I focus on first off, if I don't have any history, you know, in a production animal. But really, it's the skills that I've developed over time, you know, learning from other pathologists and my mentors—there's so many of them, you know? People who have taught me over the years, and kind of accumulating the knowledge and moving forward. There are times when I have to wait for the histopathology slides to come back before I make a definitive move on what I want to do for testing. That usually is the case when the veterinarian has not submitted a history with their submission. 

Jonathan Samuelson  11:47  
The way that this laboratory operates is, when you submit for a necropsy, you have the option to select a package where you can get a certain amount of ancillary tests, and that is included in the initial fee. So, it's very attractive to producers, you know, because they don't want me on the back end, kind of feeling like I'm nickel-and-diming them, and running these extra tests as we move forward. So, I use a lot of different things to determine what I need to test. Most of it is knowledge-based. And, knowing what types of disease affect the given organ, or specific gross are microscopic appearances of different pathologic processes—mostly cancers and infectious diseases—or, you know, even developmental things. So, you know, there's lots of hereditary diseases within sheep and goats, as well, that we kind of have to be on the lookout for from time to time.

Deborah Niemann  12:43  
Yeah. That's one of the things that— I think it was in 2020 that we submitted a 2-week-old kid for a necropsy, because she was 2 weeks old, and, like, the day before, she was bouncing around, nursing, acting 100% normal, and then she was dead. And, the same thing had happened to a half-sibling, like, a few weeks earlier. And, it was like, "Oh, my gosh, is this something genetic," because they had the same sire. And, it was a fairly new buck; he hadn't had a lot of kids. And so, it really made me worried, because it was just such a bizarre coincidence. And so, it was too late for the kid that had died a couple of weeks earlier, but we did submit that one, and it came back saying that it was just a virus—that she just had contracted a virus that had killed her. So.

Jonathan Samuelson  13:30  
Hmm. Strange.

Deborah Niemann  13:31  
Yeah, it was weird.

Jonathan Samuelson  13:33  
Yeah. Diseases... There's so many of them. And, the way that they play out, you know, there are viruses that can kill things very quickly, and the same virus might do something completely different in another animal that's generally a similar age, or something like that. And, when that happens, you know, you really need to think about other things, too, like the body's—the animal's—response to that infectious organism, right? So, a lot of times when you see, you know, acute deaths, there's either little or no immune response, right? So, the virus is kind of free to move unimpeded. And, this is really speaking in a general sense. If sometimes there's a partial immune response—right? So, you might see something more like a chronic disease, that kind of more protracted disease course. And then, they might mount a completely successful immune response, and you won't see disease at all. So, there's a lot to think about. It's not just the offending organism itself. It's the animal's response to that offending organism.

Deborah Niemann  14:38  
Yeah. It was really interesting, because it was 2020, and I had just recently been doing a ton of reading about viruses. And, I don't even remember the number anymore, because there were so many zeros and commas. Like, the number of viruses in the world is really beyond the comprehension of most of us. 

Deborah Niemann  14:56  
Viruses are just so funny. Like, it's the kind of thing that, like, yeah, it could have have affected the other goats, and their immune systems just responded appropriately, and it didn't bother them at all. And so, it was really fascinating to see that. And, so often, whenever I've had a necropsy, I have been surprised. I rarely go, "Oh yeah, I knew that." I had a doe die one time when her kids were 2 days old. And, the necropsy came back and said that she had both mastitis and pneumonia—either of which could have killed her. And, it was just like, "Oh, my gosh!' Like, you know, her udder was actually cold and floppy, not hot and hard. So, like, mastitis? Like, never in a million years would I have thought "mastitis."

Jonathan Samuelson  15:41  
Mm-hmm. Cold and floppy is not good, either.

Deborah Niemann  15:45  
Yeah, since doing the podcast, I mentioned that before, and somebody said, "Hmm, that sounds more like gangrenous-ness." Like, the really bad one. 

Jonathan Samuelson  15:54  
Yeah, those are hard. I see it with some frequency here. You know, we don't have a very high dairy caseload here. We get some. A lot of things from the university. But, when I was a kid, I grew up with dairy cows. And, we were milking one night, and I remember the vet was there—I was very young. And, he actually had removed one of the cow's quarters, you know? And, it was just this big, gross, bloody mess. And, he was there kind of treating it, and the cow was doing fine. They're just such amazing animals; they're able to fight off infection so well, you know—or wall it off, anyway, and form abscesses.

Deborah Niemann  16:31  
Yeah, that is really fascinating. 

Deborah Niemann  16:33  
So, I mentioned to you before we started recording that we had a situation recently where a 10-year-old doe gave birth to a mummified kid and a stillborn. And, the science part of my brain was like, "I want to know why." But, at the same time, the financial famrer side was like, "Okay. She's 10 years old. She's retired. She's never going to kid again. And this is the last doe to kid this year. So, you really don't need to worry about this from a herd health perspective. So, you just need to let it go."

Jonathan Samuelson  17:00  
Personally, I can tell you that it would still be important for you to get a necropsy done on those kids and that placenta, because there are infectious agents that can live within the environment, you know, and be around for next kidding season and next, you know, breeding season. So, I understand where you're coming from, with economic decisions and stuff like that. I'm always going to be an advocate for more knowledge. You know, the professor in me, right? But, there are practical realities that need to be taken into account. And, you know, if it's feasible, it's feasible. If it's not, it's not. There's other things that are available to you. 

Jonathan Samuelson  17:40  
I mean, generally, for abortions, I kind of really recommend sending the fetuses and the placenta. You know, sometimes you don't find them for a while, so the placenta has been eaten, you know, or something like that, by mom. But, this probably applies more, too, if you have a doe or a buck who dies, you know, and your veterinarian and thinks that, "You know, I think it's pneumonia. I'm hearing crackles in my stethoscope, and the doe is coughing." You know, you can have your—or you can ask your—veterinarian to perform what's called a "field necropsy." And, they can do some quick things where they, you know, have really pinpointed the disease process themselves, and they can open the animal up really quickly, and collect a small section of lung, or do a quick examination of the lung, collect some tissue, send that into us. And then, I can do the backend stuff. I can do the testing and the histopathology. You know, so it's like the referring vet is doing the gross examination, and I'm doing the stuff on the back end. 

Jonathan Samuelson  18:41  
I think other recommendations... So, like, the post-mortem interval, the way that I instruct my clients is, if you can get it to me within 48 hours, just refrigerate it and keep it cold. Because, once the animal dies, there are processes that start to take place, like auto-digestion—it's called "autolysis"—and putrefaction, so when, you know, environmental bacteria and bacteria within the animal already starts to kind of digest the animal. And, we want to avoid that as much as possible. So, if you can get it to the lab within 48 hours—that usually involves driving it there. Or, overnighting it through the mail; a lot of clinics do that as well. Then, refrigeration is all that's required. 

Jonathan Samuelson  19:28  
If it's going to be longer than 48 hours, I really recommend that people freeze the animal in at least a negative-20 degrees Celsius freezer. So, that's your kind of standard freezer, you know, in your kitchen. And, when you freeze an animal, that induces a different type of artifact called "freeze-thaw artifact." So, what happens with that is, essentially, there's water in the animal, and there's intracellular water within animals. So, when you freeze that, it forms crystals, just like it would anywhere else. And, those crystals can puncture the cell membranes. So, when you thaw the animal, it'll look like it has fluid everywhere, edema everywhere. You know, but knowing that it was frozen, you can kind of look past that and move forward. It does induce an artifact microscopically, as well. But again, I can kind of look past that. And, I still have some good cellular detail. 

Jonathan Samuelson  20:23  
But, those are some things that you can do. So generally, I say, if you can get it to me within 48 hours, let's just refrigerate it. If it's going to be longer than 48 hours, you should probably freeze it to kind of mitigate the post-mortem degradation of the animal.

Deborah Niemann  20:38  
Okay. That is really good to know, because that is something that people are always curious about. And, I remember, there was a pathologist for Michigan State who did a session at an ADGA conference once. And, he said to get the sample to them as quickly as possible, and he showed a picture of an elephant out in the desert that looked half-decomposed already.

Jonathan Samuelson  21:00  
Yeah. Those recommendations are with, like, real-life factored in, because not everybody can do things immediately, right away. You know, I would agree with that wholeheartedly. Get it as fast as you can. But, with practical realities in place, within 48 hours—refrigeration. After 48 hours—freeze it. And, we'll thaw it when it gets here. It'll delay the our examination a little bit, but at least, you know, we still have some tissue to examine.

Deborah Niemann  21:27  
And, if you're mailing it in, should they mail with an icepack or anything like that? Or if it's... How should they do that?

Jonathan Samuelson  21:33  
Yeah. Yeah, there's a lot of different things. So, animal owners can't send things directly to us. That would be through the veterinarians, because, at least at Illinois, our clients are the referring veterinarians, and the clients of the veterinarians are the owners. But, you know, definitely putting an ice pack to keep things cool will help. If you're submitting formalin-fixed stuff, you don't really need to do that. Just make sure it's in a leak-proof container, and double-bagged, and stuff like that. But yeah, you can put things on ice, especially if it's, like, fresh tissue that you're sending.

Deborah Niemann  22:09  
Is there anything else that people need to know about taking care of the body or anything like that, in terms of getting the best results?

Jonathan Samuelson  22:17  
It's really "time is of the essence." So, if you lose an animal, especially in a production setting, you know, you want to get the vet out there pretty quickly. It's not always possible. Or, at least call your vet and ask what to do, and say, "Hey, I'm not sure. Kind of think I want a necropsy. Can I just bring it to my local lab?" I mean, if you live in an area that has a local lab, which not nearly everywhere does. Or, you know, "Can we start getting the animal submitted, so we can have a post-mortem examination?" But yeah, timing is probably the most important thing, and being rather fastidious. There are, you know, clinicians in hospitals that realize it's not a practical thing for them to be able to get there quickly. So, those clinics tend to just freeze the tissue, and kind of understand that the pathologist is going to be a little bit hindered working through artifacts, you know, that arise from that freezing and thawing.

Deborah Niemann  22:17  
Okay, great. And, I also want to make sure that we point out that you're not going to get an answer 100% of the time. 

Jonathan Samuelson  23:24  
Oh, yeah, definitely. But, especially for abortions... Abortions, I would say, it's like 10 to 20% of the time I get—because there's a lot that goes into it, right? And, we don't always have all the pieces. The doe ate the placenta last night, and you know, half of the diagnostic lesions are in there. There's a lot of things. But, you know, we don't always arrive at an answer. We're not going to be able to tell you everything, because we don't know everything yet, especially in veterinary medicine. But. we're also not going to lie to you, either. You know, we're not going to tell you that there's something there that isn't. But yeah, I would say, overall, I probably find an answer in about 80 to 85% of my necropsies. So, there is some percentage there where it's, "I don't know." But.

Deborah Niemann  24:07  
Yeah. And, even the ones where you don't get a definitive answer, you are able to rule out things a lot of time. 

Jonathan Samuelson  24:12  
Yeah. Yeah, that's another great thing to point out, is because that diagnostic information can be just as useful. "Well, I don't really know what's going on, but I can tell you that it's not an infectious disease," or "I can tell you that it's not a malignant cancer that's going to wreak havoc on the animal's body," or something like that. So yeah, there are a lot of times when it's just as good to say what it isn't than what it is.

Deborah Niemann  24:39  
Yeah, I know. When I was first building my herd, we had a lot of problems with parasites and copper deficiency both, and so we were losing a lot of goats for both reasons. And, for whatever reason... Maybe I just got really paranoid in thinking, "It can't be something so simple as these two things." And, I really started to worry that it maybe it was Johne's or something. And, it was really comforting to me to have the vet that I was working with at the university say, "No, it is not Johne's. Your goat does not have Johne's." Like, it would be really hard to miss Johne's on a necropsy, so you would know that if that's what it was.

Jonathan Samuelson  25:16  
Yeah, definitely. And, Johne's in particular has a very, very particular and specific lifestyle. So, you know, in animals under, you know, a year and a half, two years of age, I know it's not, Johne's, because it doesn't come into being—you know, or causing disease—until they reach adulthood. They contract it when they're young, but it takes a while to develop the actual clinical signs and symptoms that you see from the disease. 

Deborah Niemann  25:43  
Yeah. Anything else people need to know about necropsies?

Jonathan Samuelson  25:48  
As far as, like, owners and submitting things, you know, there's a lot we can do. And, there's a lot we can't do. You know, generally our goal is to get an answer and to provide a service that can be invaluable at times. And so, it's a really good thing. 

Jonathan Samuelson  26:02  
It's a really rewarding career. Especially if you have interest in science, and if it comes to you naturally, this is a great career. Like, I knew about pathologists before I went to vet school, but my understanding of them was they were these kind of, like, mythical beasts that lived in south San Francisco and worked for pharmaceutical companies. You know, that's a big area of employment for us, is in pharmaceuticals, and research and stuff like that—and drug development. But, it wasn't until I was actually in vet school, and I started being exposed to the pathology in class and stuff like that, and I realized that, "Wow, this is great!" They kind of call pathologists "the specialist for specialists," you know, because I'm kind of—not completely, but kind of—the end of the road with being able to get a diagnosis and an answer. 

Jonathan Samuelson  26:51  
So yeah, I mean, it's a great tool that's available to animal owners everywhere.

Deborah Niemann  26:56  
Well, thank you so much for joining us today!

Jonathan Samuelson  26:59  
Yeah, no problem! I was happy to be here. This is my first podcast, so— 

Deborah Niemann  27:04  
Awesome! 

Jonathan Samuelson  27:05  
—I'm very excited and very happy to tell your readership or listenership about necropsies in animals.

Deborah Niemann  27:13  
And that's it for today's show. If you haven't already done so, be sure to hit the "subscribe" button so that you don't miss any episodes. To see show notes, you can always visit ForTheLoveOfGoats.com, and you can follow us on Facebook at Facebook.com/LoveGoatsPodcast. See you again next time. Bye for now!

Transcribed by https://otter.ai