Veterinary Vertex

Same Lifespan, More Challenges: PPID in Horses

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A shaggy coat and a creaky stride don’t have to signal the end of the road. We unpack new primary-care evidence on pituitary pars intermedia dysfunction (PPID) showing that diagnosed horses can live as long as matched controls, even as they experience more medical events along the way. That insight changes how we talk with owners: from doom to diligence, and from a single prescription to a complete, daily management plan.

We sit down with researchers Drs. Emma Stapley and François René-Bertin to break down what PPID really is—and why it’s not the same as “Cushing’s” in people or dogs. You’ll hear how they built a robust control group by matching age, breed type, and even owner to cut through referral bias. We dig into the laminitis connection, the role of insulin dysregulation, and why the oral sugar test is your best entry point. From there, we move into practical monitoring: post-meal insulin checks, seasonally aware testing, and how owners who give pergolide daily often catch subtle changes earlier.

Treatment is more than pergolide. We map the full-care toolkit: low-NSC diets tailored to the individual horse, ration balancers that avoid unnecessary starch, exercise that builds muscle without overloading feet, and farriery that supports comfort and function. Body condition is a quiet lever with outsized effects; holding a steady, moderate score can rival medication in shaping outcomes. We also surface often-missed comorbidities—slow wound healing, hyperinsulinemia-associated laminitis, and dental issues like EOTRH—and explore emerging questions around calcium and vitamin D that may link neuroendocrine change to oral health.

If you work with senior horses, manage a barn, or simply love a hairy retiree who still wants a job, this conversation gives you a clear, evidence-based playbook. Subscribe, share the episode with your barn friends, and leave a review to help more horse owners find science-backed guidance. What PPID myth have you struggled to debunk? Tell us after you listen.

JAVMA article: https://doi.org/10.2460/javma.25.08.0533

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Lisa Fortier:

Welcome to Veterinary Vertex, the AVMA Journal's podcast where we delve into behind-the-scene looks of manuscript authors. I'm editor-in-chief Lisa Fortier, and I'm joined today with Associate Editor Sarah Wright. Today we're discussing life expectancy in horses diagnosed with PPID and endocrinopathy in horses is such an emerging and important topic. And of course, I'm always happy to chat about an equine manuscript. So, Emma and Francois Rene, thank you for being here with us today.

François René-Bertin:

Thank you for having us.

Emma Stapley:

Thank you.

Sarah Wright:

Thank you for joining us, Emma and Francois Renee.

Lisa Fortier:

All right, Emma, let's start with you. Can you briefly describe the center question of your study and what motivated you to investigate this PPID in horses?

Emma Stapley:

Absolutely. So kind of our central question was what we could do to a little bit more clarify the overall picture of PPID and primary care practice. A lot of the retrospectives that have focused on PPID, beyond just the clinical presentation, have focused on referral populations, and that's automatically going to select for more severe cases, more complex cases, and owners who are able and willing to follow up on that referral care. So we felt it would be really useful for primary care practitioners across the country to just have a little bit clearer picture of what that's going to look like day-to-day on the farm.

Lisa Fortier:

I love one of the central things about your manuscript is that you had a control group. How did you go about selecting that group?

Emma Stapley:

Absolutely. So the PPID cases were easy enough. We were just looking at basically any horse or pony that was diagnosed by one of the veterinarians in our practice. But we wanted a control group that was going to effectively, you know, give us as much of a accurate comparison as possible. So we looked for age matching, breed type matching, and owner matching. So we only picked horses who are 11 years of age or older. So they had to survive to essentially the same point as our PPID horses. Again, we tried to age match them to their actual horse they were controlling for as closely as possible. And then we looked at um similar breed types for each case. So again, we didn't want to be um looking at insulin dysregulation and say comparing a bunch of morgans with PPID to a bunch of thoroughbred controls. And we didn't want to be looking at ocular issues and a bunch of Appaloosas with PPID compared to Morgan controls. So we wanted to make sure that was as close as possible. And then we also really wanted to control for owners. So we felt if an owner had one animal diagnosed with PPID, that indicated a willingness to test for PPID if their veterinarian were to recommend it. Um so we felt that if a control was with an owner who had a diagnosed PPID, that meant that that their other case was less likely to have needed a diagnosis as well. Um that also controlled for socioeconomic status as much as possible, a whole host of management factors and then risk aversion as well of was this owner willing to hand walk a colic themselves and not call the vet, or were they going to call the vet on all their courses, hopefully at about the same rate?

Lisa Fortier:

Yeah, I I think your control for owner is fascinating. As you're explaining those things to the listeners, I'm like, yep, I checked that box, I check that box, that person next to me in the next all checks that box. So really beautifully done on selecting control cases.

Sarah Wright:

And Francois Renee, for listeners who aren't equine specialists, what is pituitary powers intermedia dysfunction or PPID, and how does it typically present in older horses?

François René-Bertin:

Yeah, so I mean, PPID is what we use to call Cushing's disease. So I think many of the listeners here will have heard that before. So Cushing's disease, you see that with the older, hairy horse with sweaty, uh, has recurrent infections, potentially a snotty nose, uh, potentially some laminitis or some lameness. Uh so this is yeah, this is the core of the disease and the clinical presentation. So the reason why we call it PPID now and not Cushing's disease is that it seems that the mechanisms behind the disease are a little different. Uh so when we have Cushing's disease, we think about the human disease, we think about the canine disease. Uh, it's a little different in horses, um, and it's not exactly the same hormones that are involved. Uh so it seems that actually PPID in horses is closer to Parkinson's disease in people. So you have the involvement of the endocrine system, you have the involvement of the neurologic system. So um it's a little different. But yeah, some of the clinical picture is the same, is those older horses with long hair uh that are sweaty, that are lame. Uh so yeah, this is the typical disease that we were looking into.

Sarah Wright:

Yeah, as you're describing that, I'm literally picturing like the horse in my lecture notes from vet school. Like, yep, I can see to my head.

François René-Bertin:

I mean, it hasn't changed much. I mean, hopefully we do a little better now, but yes, it's still that yeah, a very old horse with long hair that looks like a sheep.

Sarah Wright:

Yep. And what inspired you to focus on PPID specifically?

François René-Bertin:

I really have a passion for laminitis, and I really want to understand what causes laminitis. And we know that most cases of laminitis uh have an endocrine background. So I'm really interested in insulin dysregulation, equal metabolic syndrome, and TPID. So I really want to understand the mechanisms behind laminitis and how do we connect from those, I mean, from that hairy horse to the laminitic horse. What is the link there? And this is really why I want to understand better uh those mechanisms so we can help those horses. I mean, I mean, I think laminitis is something that every equine vet and every horse owner has dealt with, unfortunately. I mean, foundering horses, it's a picture that you have in your mind, and it's so painful that really feels the pain of the horses. Uh, so we really need to do something about that. And I really want to, yeah, really investigate what's happening behind the scene. Why do we go from the hairy horse to the fat horse to the lame horse and what's happening there?

Lisa Fortier:

I like what you said about basically insulin dysregulation and all of these metabolic horses. Uh, and I get the insulin of my horse measured at least twice a year, you know, depending on grass and all those things. What do you guys recommend as veterinarians for measuring insulin in horses?

François René-Bertin:

So, the recommendation that we have for that, I mean, and I guess I will cite the equine endocrinology group and the recommendations that we publish uh every year for that. Um, the first thing would be to test the horse uh with an oral sugar test. That will give you the risk that the horse has to develop laminitis and to have insulin dysregulation. Then, once the horse has been diagnosed, you implement the changes in diet, and then the best test for that would be to actually see what the horse does with the current management. So you feed your horse and you measure that insulin about two hours later, and that will give you the specifics of this horse in this very situation with that diet is able to handle or not handle that management. Um, and I think what you're describing is really good. I mean, we really need to have more owners test their horses regularly. Um, I know it is expensive to measure insulin, but managing laminitis is even more expensive.

Lisa Fortier:

Exactly what I was gonna say.

François René-Bertin:

It is better to test your horse often. And with season, we know that the composition of the grass will change. We know that the availability of the diet, of the hay will change, and horses do get older, and we know that when they develop PPID, they are more likely to develop insulin dysregulation. We know that with age, they are more likely to develop insulin dysregulation. So it's not because the horse was tested once and tested negative that the horse is negative for the rest of its life. I mean, in most cases, it is true it is great, but unfortunately, things change and horses will develop insulin dysregulation.

Lisa Fortier:

One of the key findings in your manuscript, uh, Emman and Francois Renee was that horses with PPID did not have a shorter life expectancy than controls. Was this surprising?

François René-Bertin:

Yes, it was surprising because the hypothesis we had was that in primary care, horses with PPID would die early. I mean, we would think that um it's not the same population. As Emma was saying, referral practice, you have wealthier clients, you have clients who are able to do more. So that would be a little biased. Uh and we thought that, yeah, in primary care, people have the mean they have, people are able to deal with the cases the way they can. And we would think that, yes, PPID would be a death sentence. Uh, but it was not the case. And we were really happy to be proven wrong with that. And there are a few other studies that actually looked at that as well and support what we have. Um, it's always hard to design some survival studies because there are many reasons for why a horse would leave a practice. Um, and with the control matching that we were trying to do, we were hoping that we were that horses were as likely to leave the practice if they had PPID or if they did not have PPID. Uh, but we were really happy to find that yes, PPID is not a death sentence. Um we had a population that was mostly treated, so that has an impact on that as well. Uh but if you look after your horse, it hasn't had PPID, it's not going to be a death sentence. The horse can still do something, you can still ride your horse, you can still have an active horse, they still have a role uh in society.

Lisa Fortier:

Yeah, I I think the best studies that we do are when we're wrong, because we just learn so much and it's like mythbusters. Hey, Emma, equally important was that horses with PBID experienced more medical events during their lifetime. Could you share with us a few examples of these comorbidities that occurred more often in the PPID group than their match controls?

Emma Stapley:

Yes, absolutely. So again, when we think about PPID, we think of a whole host of a potential clinical signs. So they can have tendinopathies, they can have increased risk of corneal ulcers. There's all these things that we know are associated with this with this disease, but we wanted to see if those were occurring at different frequencies between our PPID cases and our controls. So again, we looked at a total of 2,914 medical events across our 406 horses. And out of that, we only had four different types of medical events that were significantly different between the two groups. Um, so first of all, our PPID group were more likely to have a course of NSAIDs prescribed than our controls. And we don't necessarily think that's, you know, NSAIDs having anything to do with PPID itself. That's more so that these animals were having more inflammatory events that needed NSAIDs to treat them. Um, and that was kind of how that came out in the data. Um, very unsurprisingly, as we've been talking about, um, they were more likely to have hyperinsulinemia associated laminitis diagnosed compared to controls. Um, also unsurprisingly, they were more likely to have poor healing reported on by their primary care vet. Again, any lesion that they felt wasn't progressing appropriately. Um, and then lastly, they were more likely to have either a missing tooth or to be diagnosed with equinodontoclastic tooth reabsorption and hypercementosis. And so that was a little bit of a surprising finding to us again. Um, that does kind of go along with previous work that in a group of EOTRH horses, um, they were more likely to have PPID compared to age match controls without. So we're starting to see a little bit of interesting overlap with that disease. And it was interesting to have the study support that as well.

Lisa Fortier:

I I think it's fascinating that you had such good medical records that you can link a missing two.

François René-Bertin:

Yeah, we have to thank the Equal and Field Services at Purdue University for that and their students. I mean, the I mean, medical records in practice are not easy. And we I mean Emma did a great job going through those records. And I mean, she has shown resilience to go through that. But yes, I mean the equal field services were fantastic to fill their record and the students were great.

Emma Stapley:

And again, I know when I was working in equine ambulatory practice, I was not keeping that detailed of notes, and I was kind of a little bit blown away by the detail we were able to get.

Sarah Wright:

Certainly makes you appreciate it. Yeah. And Francois Rene, from a clinical perspective, how should veterinarians interpret the findings that PPID horses don't necessarily live shorter lives, but do experience more healthcare events?

François René-Bertin:

The main message is that, yeah, PPID is not a death sentence. It is worth treating your cases. Uh, if you can afford Progolide, yes, it's going to be an expense, but I think it is really something that will bring some results. We have shown before that um horses treated with progolide are going to survive better, are going to survive longer. And it's not because they have PPID that they're going to have uh a shorter life. So people can still ride their horses, people can still do something with them. It's really not a death sentence. Yes, they will have more uh medical events, uh, but this is something I think we might have a bit of a bias there as well, because when an owner has to give appeal to a horse every single day, they are more likely to detect small changes, uh, especially in older horses when potentially they are retired, they are out of the pasture, and you do not keep a close eye on them. And the fact that the horses that we had here, PPID, were more likely to be on the farm with the owner, were more likely were treated and receiving a pill every day. I think owners were detecting that, oh, this morning my horse has a sturdy nose, oh, this morning my horse has a close eye. And they're more likely to report those things, they're more likely to have the vet go there. So I think this is potentially improved care for the horses. The fact that we have that um collaboration between the vet and the owner and looking at that aging horse. Um, I think this is actually a good thing that you do not leave your horse in the pasture alone. Uh you really do something with that horse. So, yeah, my message for the vet would be test your horses and treat them. And for the owners, it would be the same. Yeah, make sure to keep a close eye on your horse. And age is not a disease. You really need to have your uh, I mean, you have a companionship with that horse. So really enjoy that. And in the golden years, you could still have a relationship with that horse.

Lisa Fortier:

Yeah, I think that's really important. You often hear at the barn people saying, Oh, now my horse has this, now he has that. He's just getting old. And I, you know, I'm not they're treating veterinarian, so I just kind of shrink away in the corner and mention something to the barn manager. Like, I think that horse should be tested. Uh it's it's really easy for people to think, oh, you know, like I said, just getting older has too many miles on him or her. And then they just, the owners just kind of give up, and then the horse deteriorates faster and further.

François René-Bertin:

I mean, I think we're doing better because that was another finding that we had in the studies that um more, I mean, of uh over the years we had more and more testing and more and more positive cases. So I do not think that PPID is becoming more prevalent. I think we are getting better at detecting it. I think the owners are being better, more willing to spend the money on testing or calling the vet because something is wrong. So I think we are making some improvement there. But I completely agree with you. I mean, it's not when you should not tell your horse that it's you're also not going to look at you anymore. It's it's not fair.

Lisa Fortier:

I very much agree. Emma, I think your data shows that the increased frequency of lifetime medical events does reflect PPID. But how could it also relate to how aging simply interacts with the endocrine dysfunction in horses?

Emma Stapley:

Absolutely. So again, when we think about PPID, it's always going to be an age-related disease. It's always going to be degenerative. So it's always going to be overlain with that aging process. We don't know what PPID looks like in a young horse because it doesn't and can't happen essentially. Um, but what we're increasingly seeing from this and other studies is that PPID is going to be another one of our risk factors with increasing age for a lot of things. So it's essentially going to exacerbate certain parts of the aging process. So again, age isn't a disease, but it can certainly be a risk factor. So it's going to be a risk factor for decreased tolerance for dietary carbohydrates, corneal ulcerations, soft tissue injuries, a whole, a whole host of things. But PPID is, again, going to be another risk factor and can essentially amplify those things in these horses.

Sarah Wright:

And Emma, based on your findings, what practical advice would you give equine practitioners when evaluating, monitoring, or treating horses diagnosed with PPID?

Emma Stapley:

So I definitely emphasize all aspects of husbandry in these animals. Um and again, that that pergolide, even though this is our go-to therapy for this disease, um, replacing that that lost dopaminergic inhibition, um, it's not going to be a monotherapy in these cases, as Franco Renee has been emphasizing. Um, we need to take care of all aspects of husbandry in these animals. So we have, we found that um when horses had laminitis in our control group versus our PPID group, they weren't more likely to have it reoccur in the PPID group versus the control. So it wasn't like we put them on pergolite and their laminitis risk went away completely. It was still an issue of we had to get their dietary carbohydrates under control, manage their exercise regime, anything like that that we can do for these horses. And so even though medical therapy is really important, we still need to be thinking, is the diet high quality and appropriate for this animal? Is their exercise regime maintaining a good muscle mass? Do they have um good quality hoof care? Or, you know, is their pasture, you know, you know, going to be good footing for them, all sorts of different things that we can add on. So it's not just a, you know, we need to diagnose this horse and get it on treatment. We need to diagnose this horse and start going through its management with a fine-tooth comb of saying, what all can we do for this horse? And so again, in um a little bit more that we're continuing to do with this kind of wealth of data that all of our fabulous people um Purdue students have left us, um, is we're starting to look at, you know, how these horses progress. And what we're finding in that and in a previous study that Frontier NASA's lab group has done, um, is that even though pergolite is associated with positive outcomes, so survival, hormonal improvement, um, all of that, um, having an adequate body condition score is effectively equally as important. So again, if these horses are obese or very thin, they're gonna have a worse outcome compared to an animal that's sitting, you know, at a nice five and maintaining a good overall condition. So again, this isn't a set it and forget it with pergolide. This is a what is every little tweak we can do for management to make sure this horse has the best outcome possible.

Sarah Wright:

And are there any specific preventative actions or monitoring strategies you've prioritize?

Emma Stapley:

Um, so unfortunately, um, as far as we know yet, there's there's nothing we can do to prevent PPID because we we can't prevent the aging process. So um unfortunately, prevention is a little bit tricky in terms of PPID itself, but there are things we can do to prevent those comorbidities. So again, we can, as soon as we know about this disease, we can start, you know, watching for things that could contribute to a laminatic event. We can start, you know, making sure we're we're working to manage all those other things that PPID is a risk factor for and getting them on treatment as quickly as possible to again um get that endocrinopathy under control as much as possible. Um, all of these things are are gonna contribute to a good outcome and monitoring that um those endocrine changes over time, that just because their their starting dose of pergolide has a good effect, it's going to continue to be a degenerative condition. So we need to keep monitoring them um both in terms of their hormonal response and in terms of their clinical response. If they all of a sudden start losing weight, we need to address that um both hormonally and in terms of overall management.

Lisa Fortier:

I think the hardest thing to manage is obesity. You know, people just assume the horse needs a bunch of grain and uh every barn that I've been at, and like my horse gets a cup of ration balancer and they think like I'm I'm being cruel to my horse, and like he's still a six slash seven, like he doesn't need that.

François René-Bertin:

Yeah, this is a tough battle. I mean, the um understanding of owners of body composition of horses is really tough. Uh, if you take the example of the pony clubs and things like that, I mean the Welsh ponies they're really fat and uh they're really expected to be fat, and this is really problematic. And people do have a misunderstanding of what's muscle mass, what's fat mass, and what it's supposed to look like. And as Emma was saying, is we really need to make sure that those horses keep a nice muscle mass, but we do not need that fat mass. We really need to be at that five out of nine with a proper diet. Um, and this is something that is often neglected. Uh, I mean, something like sweet feet or things like that are going to be problematic for those horses, are not going to be able to handle uh all those sugars as well. Uh, and there's still a bit of confusion between insurance regulation, equomethalic syndrome, and PPID. And a lot of times we do not have obesity in uh PPID horses. They actually tend to be on the thinner side, especially in the later stages. So they have no muscle, they have no fat. And unfortunately, we still have some owners that would starve those cases and consider that they are the same conditions and we need to reduce the intake for those cases. And really, we do not. We those cases would actually need to have more. And we can potentially add more fat and fiber to those cases to really build something and get them moving to build some muscle mass. But yeah, this is, I think, I mean, I couldn't speak for hours on that, but it's something that we really need to uh to address. I mean, uh, horses need to eat better and we need to change their diet or adapt that as they age and as they give it up some medical conditions.

Lisa Fortier:

Emma had mentioned earlier, like you still have a lot of really cool untapped data out of these medical records. But what are some of the other key unanswered questions or next steps in this research area?

François René-Bertin:

I think we would go back to the dental data. And um I think that is very intriguing. And I think Emma is going to spend a lot of time working on that in the next few years for the rest of her PhD. Uh, it will be the um the role of um of calcium in that. So it seems that for EOTRH, hypovetabinos D is a risk factor. It seems that uh for Parkinson's disease, which is the disease that would be actually closer to PPID, we do have an involvement of calcium. So this is something that uh we're going to look into a bit more. So uh this is really uh a novel uh field. Um, and uh we're really uh yeah, trying to tackle that to really put the connection between the neurodivided disorder that PPID is and the clinical picture that we can have. That will be Emma's job for the next few years.

Sarah Wright:

Emma sounds like you're gonna be really busy then. Very much so. So well, we look forward to hopefully receiving more manuscripts from you. Yeah. So, Emma, what was the most unexpected challenge you encountered during this study?

Emma Stapley:

Um, so a little bit going back to the medical records again, even though they were phenomenally detailed, there were just some times where you were you wished you could have been there in the room and and said, what were you actually looking at? What, you know, what were you actually seeing? Um so just trying to to parse that out into something that we could, you know, compare across horses, that we could have that um a little bit comparing apples to apples when it was you different students, different days. Um and again, I think we were able to do that, but again, it was a little bit of a challenge to go through in a little bit, say what, you know, what did you for sure mean in this case? But but overall the records were were really great.

Lisa Fortier:

That's amazing. If it um if you could design a follow-up study to be performed next, I'm sure you're already thinking about this. Uh, would it be dental disease or what else might it focus on? I think dental disease is fascinating, especially the toothless.

Emma Stapley:

Yes. So um, so in terms of to follow up this study specifically, it would be phenomenal if we could look at a group of horses, effectively get a couple breeding farms involved and have their foals from from the second they hit the ground and just follow them out across their life. Again, that would be a very, very, very involved study. But again, that would give us our best picture of when does this develop? How do these horses actually compare over their full lifetime? Um, and again, get some different breeds involved and really look at these horses, start monitoring them. Um, so that would be how I would follow up this specific project. In terms of the calcium, um, we're starting to look at um markers of calcium metabolism over the course of the year. We know that we get really significant fluctuations in um our PP, our PPID associated hormones um over the course of the year. How does that affect calcium metabolism over the course of the year? Um, starting to look at changes um in the the overall skeletal system specifically. How does that affect bone neural density markers of of um bone metabolism and and kind of going from there with these horses? I think there's a lot of it's uh it's gonna be quite an exciting field for for quite a while, hopefully.

Lisa Fortier:

Those shortage in those PhD chapters.

François René-Bertin:

Yep.

Sarah Wright:

Well, Emma and Francois Renee, thank you so much for being being here today. We appreciate you joining us and also for submitting this manuscript too to Javma.

François René-Bertin:

Well, thank you. It was a pleasure.

Emma Stapley:

Thank you.

Sarah Wright:

And for our listeners and viewers, you can read Emma and Francois Renee's article on JAVMA. I'm Sarah Wright, here with Lisa Fortier. Be sure to tune in next week for another episode of Veterinary Vertex, and don't forget to leave us a rating and review on EPA Podcast or wherever you listen.

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Lisa Fortier, DVM, PhD, DACVS

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Sarah Wright, DVM

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