Veterinary Vertex

Challenging Radiolucent Stone Detectability: Cystine and Urate Cystoliths

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Can radiolucent stones really be seen on radiographs? Discover the surprising answer as we unpack the world of cysteine and urate cystoliths in dogs with our guests, Drs. Rachel Williams and Camille Andrews. Rachel shares groundbreaking insights from her study at a high-volume academic institution, challenging long-held beliefs about the detectability of these stones. Camille adds depth to the conversation by highlighting the importance of a holistic clinical picture, including breed, sex, and urinalysis findings, in predicting stone types and formulating effective treatment plans.

This episode examines the evolving landscape of empirical treatment recommendations for cystine and urate cystoliths. The conversation further expands to discuss less invasive stone identification methods, strategies to manage recurrent calcium oxalate stones, and the potential of artificial intelligence in predicting urolith types. Learn from the experts about tailored approaches for stone removal and the critical role of thorough stone analysis, ensuring every pet gets the best possible care. Don't miss this comprehensive and insightful episode packed with practical advice for veterinary professionals.

JAVMA article: https://doi.org/10.2460/javma.24.05.0302

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Speaker 1:

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Speaker 2:

You're listening to Veterinary Vertex, a podcast of the AVMA Journals. In this episode, we chat about how cysteine and urate systolus and dogs are frequently visible on radiographs prior to surgical or non-surgical removal, with our guests Rachel Williams and Camille.

Speaker 3:

Andrews, welcome to Veterinary Vertex. I'm Editor-in-Chief Lisa Fortier and I'm joined by Associate Editor Sarah Wright. Today we have repeat guests Rachel and Camille joining us. Thank you again, both of you, for being with us here again today and Camille joining us. Thank you again, both of you for being with us here again today.

Speaker 2:

Thanks for having us All. Right, let's dive right into the fascinating world of systolites. So, rachel, your JABMA article discusses how cysteine and urate systolites in dogs are frequently visible on radiographs prior to surgical or non-surgical removal. Please share with our listeners the background on this study.

Speaker 5:

Yeah, so kind of how we got interested in this is at our institution we do a ton of urinary surgery. It's definitely one of the more common things that we do, kind of all along the urinary tract, so removing stones from ureters, bladders, urethras, stuff like that. And we happen to notice that a lot of our stones that were coming back were what are classically called radiolucent stones, or ones that don't show up on radiographs or x-rays, and when we went back and looked at those records we found that a lot of them were diagnosed on radiographs, which didn't really make sense given the historical information that's out there, and so it's something that we wanted to look at in a little bit more detail. Is this a fluke? It's just a couple of cases and we're kind of paying attention to it because we've had a sudden little focus of them or is this something that is actually happening in a higher frequency than we previously realized? And we wanted to figure that out and, if our hypothesis was correct, we got that information out there to help clinicians in practice.

Speaker 2:

Yes, it's a super clinically relevant topic and also something near and dear to my heart too. I have a cat who's a stone former, so I'm always trying to say prize the literature to see if I can help her any better. So, camille, what are some of the important take home messages from this Chafma article, from this Chafma article.

Speaker 4:

Yeah, I think, kind of alluding to what Rachel had mentioned, the biggest take-home message is that cysteine and urate stones both are very frequently visible on digital radiography at rates for urates of 85% in our data population, which spanned it from 2019 to 2023 in dogs, and for cysteine stones it was over 90%, at about 92%. And this is really important because radio opacity alone may have been previously used as sort of a predictor of stone type, meaning that even if a stone was seen, it was immediately classified into that radiopate category. So calcium oxalate and struvite stones, and additionally, with that kind of designation, the prescription of a dissolution diet, which is what only labeled for struvite stone dissolution, may have been the next step, and that has no use for cysteine and urate stones. So therefore, aside from the radio opacity of stones, significant factors like signalment, breed, sex, urinalysis findings like the presence of crystals in a urinalysis, an overall clinical picture, should be considered almost more important in anticipating stone type and therefore possible treatment recommendations than radio opacity alone.

Speaker 3:

Okay, yeah, thank you, camille. It's not just your dogs, right? I'm a large animal surgeon, so those little goats this is really important for them as well and I really like how you emphasized it's important for your treatment recommendations, while hopefully you sent the stone away for analysis and if you didn't, you probably should be thinking about it, even more so in light of your and Rachel's findings. Absolutely, camille, while I have you, what sparked your research interest in systolus, not the sexiest of topics.

Speaker 4:

Absolutely. I think what is so great about researching something like systolus is they're ever present in veterinary medicine small animal medicine, large animal medicine from general practitioners to emergency medicine, to a specialty clinic like UF, and so urinary surgery, moreover, is a common next step in treatment recommendations, and so I think it was kind of an interesting topic to look at, because of how prevalent both systolists are in general and also urinary surgery, and any information that we can publish regarding systolists can kind of be applicable to a wide audience.

Speaker 3:

Great. So I hope some of those ruminant surgeons out there are listening as well, and the practitioners. Rachel Camille talked about some of the important findings of the manuscript, but always when we do things like this, there's other things that surprise us that weren't even part of your hypothesis. So what were some of the most surprising findings from your article?

Speaker 5:

Yeah. So I think something that really surprised me. I wasn't really expecting to find this information or have it be quite as significant as it was, but we had a higher percentage of cysteine stones found in our population compared to what's reported in previous reports. So you know, often University of Minnesota is putting out kind of some information about proportion of stone types, and that information is really important for us when we're looking at patients, really regardless of species although species is a part of that consideration to figure out what stone type is most likely and guide some empirical treatment recommendations or at least further diagnostics. And so the fact that we found cysteine in such a high proportion is interesting and surprising, and we speculated on a couple different reasons for this. So it could be as simple as the fact that this was a study done at the University of Florida, which is a tertiary referral hospital, and we know that those institutions are going to be more likely to get something that's a little bit weird, a little outside of the norm, and so it's certainly possible that we just have a higher proportion of those cases compared to what people are seeing either in secondary referral centers, in private practice or perhaps in general care, emergency and urgent care facilities.

Speaker 5:

I think that's something that definitely a little bit further investigation could be done to tease that out.

Speaker 5:

But we also know that these stone types are overrepresented in French bulldogs specifically, and we know that we have a lot of French bulldogs in this study, and so you know there's the question is that playing a role in things?

Speaker 5:

And is this an indicator very, very early on that maybe the prevalence in different stone types is going to be changing over time, especially as the popularity of the French bulldog increases? We're already seeing changes in some of what our industry sees, at least on the surgery side as far as common procedures, because of the popularity of the French bulldog it's the number one breed in America two years in a row, and I don't think that's going to change anytime soon. And so very surprising, very interesting a lot of theories for why that was the case in our data, and I think it's something we should be keeping an eye on in the years to come because I think it is possible that it may end up changing some of the recommendations that we make for patients, just kind of playing the rule of odds in a way, as far as what's going to be the most common stone type.

Speaker 3:

Yeah, the Frenchie. That should be the whole podcast. Why not to own a Frenchie unless you really want to pay your vet bills? What was the name of that French bulldog that won the Westminster? That really started all of this?

Speaker 5:

Oh, it was so cute, I don't remember his name, but it was pretty cute. I mean I can see why people love them. I can. They're very sweet, they're very affectionate. They also just come with a lot of medical issues.

Speaker 3:

I mean, he was a rock star and he knew it when he hit that turf.

Speaker 2:

Oh yeah.

Speaker 3:

Rachel, while I have you, what do you think are the next steps for research in this area of systolus?

Speaker 5:

So I think one of the big things that is an area of much needed investigation is coming up with a less invasive way to really identify what stone type is prevalent in a patient.

Speaker 5:

Right now we have to get a sample of the stone, so not just crystal urea on a urinalysis. We have to get a sample of the stone, so not just crystal urea on a urinalysis. We've identified that that is not always consistent with the stone type that's present. And of course we know that the shell of a stone can be different than the core of the stone, which can pose some issues with figuring out what type is present without sampling an entire stone. And the best way to get those stones is cystoscopic retrieval or surgery, which are relatively invasive and they can be costly for the client, and so when there are some financial limitations that are present, it's really challenging to appropriately treat that patient for either their lower urinary tract signs or even potentially obstruction.

Speaker 5:

And so finding some way to increase our suspicion of a certain stone type I think is something that needs to be investigated in the future. And then going along with that and I'm sure Sarah will agree with this if her cat is a stone former is looking at other methods of stone prevention. So some stone types are more or less preventable. We know that struvite is the only one that's truly able to be dissolved, and so, really, efforts for all of the other stones center around prevention instead of dissolution. But calcium oxalate, for example, is exceedingly frustrating to prevent, and we do see patients become recurrent stone formers, and then we're in the situation again of potentially having to pursue costly diagnostics and treatment options, and so exploring better or different methods for prevention, I think, is something that we need to look at as well.

Speaker 2:

No, I definitely agree with the prevention for stone formers. Like I said is, owning a stone former is exceedingly frustrated. We've tried all the things to lower her calcium levels. My goodness, little cat is determined to have the highest calcium you've ever seen.

Speaker 3:

Oh no, yeah, it's challenging Camille hot in every area of medicine is artificial intelligence. Do you see a role for AI in this area of research?

Speaker 4:

I could definitely see a potential role for AI, role for AI. Both the University of Minnesota and, more recently, the AMC have sort of published an algorithm to potentially help to determine urolith type, and I could definitely foresee kind of AI getting involved with that sort of algorithm formation, pulling together some of those factors that I had mentioned previously signalment, breed, sex, things like that urinalysis findings to help kind of predict urolith type. However, I do think that in the determination of treatment recommendations it is very dependent on the whole clinical picture of the animal, and so I think that that is something that AI won't necessarily be able to fully elucidate. And while maybe on the predictive aspect AI has some potential uses, I think it would be challenging to foresee AI being able to take it from A to Z completely.

Speaker 3:

Makes sense, it might assist, but it certainly isn't going to replace veterinary medicine anytime soon. Lucky for us.

Speaker 2:

Most definitely. Also, the famous Frenchie is Winston. So for any listeners, winston, the Frenchie there, and for those of you just joining us, we're discussing how cysteine and urate systolic dogs are frequently visible on radiographs prior to surgical or non-surgical removal, with our guests Camille Andrews and Rachel Williams. So a little bit more to talking about you both. So, rachel, how did your training prepare you to write this article?

Speaker 5:

So I was fortunate to do my residency at the University of Pennsylvania with a really, really fantastic urinary surgeon, dr Lily Aronson. So shout out to her. She every day still instills a lot of surgical wisdom into her trainees, and she encourages us to question the status quo and not just do something because it's what everyone else does, and kind of question dogma as well, and so you know, she continues to be a constant source of inspiration to me. I think there's no way that you train with Dr Aronson and you don't end up loving urinary surgeon. I think it's just impossible. Her love, her passion, her enthusiasm is so contagious, and so she really sparked that fire in me early on, and so that's something that still promotes my interest and drives me in that way.

Speaker 2:

Yeah, our mentors can really have a huge impact on us. I was actually. I met up with a friend from vet school over the weekend and we were talking about mentoring veterinary students and you know she's kind of mentoring that maybe it's not not her favorite thing and I was like, oh my gosh, I love it. I'm like I had such great mentors. It's really cool to turn around and help the next generation.

Speaker 5:

So yeah, a great mentor can make all the difference in the world.

Speaker 2:

A hundred percent. I definitely agree. Now, this next set of questions is going to be very important for our listeners. So, camille, what's one thing the veterinarian should know before discussing systolus with the client?

Speaker 4:

I think discussing those particular signalment factors and suspicion for comorbidities that may raise flags for a veterinarian as sort of a predictor of stone type, despite radiopacity, like male intact brachycephalics, as Rachel mentioned for cysteine stones, a dalmatian or suspicion or presence, known presence of a portosystemic shunt for urate stones should sort of be those you know flags that kind of raise that may make it more likely or not to take the next step and something like a dissolution diet. Additionally, the other thing that we noticed when we were able to bring in Dr Grosso, a radiologist at the University of Florida, was that interestingly, the stones varied very frequently in both size and number on radiographs. So that is something that was much less predictable for their stone type. So both cysteine and urate stones ranged in from one to few to many stones on radiographs and additionally the other thing that really ranged was size in both kind of sects of stones Some were less than a millimeter and some were almost greater than a centimeter.

Speaker 2:

And then, on the other side of the relationship, what's one thing clients should know about systolic?

Speaker 4:

Yeah, I think, talking about how systolic can be removed by various methods, I think is important for us for a client to know and also know that potentially, if they hit the jackpot and it works, potentially a diet could help. However, as Rachel mentioned earlier, to know if a dissolution diet may actually help, it's important to have that confirmation that struvites were found in a certain stone population. Different interventions exist, those like cystoscopic methods, the use of camera, use of high pressure water, urohydropulsion and then, of course, surgical methods anywhere along the urinary tract, and the recommendation of these different interventions does still depend on that clinical picture. So while a, you know, a large breed female may be more and more able to go for something like a basket cystoscopy compared to a very small dog, it really depends on sort of that overall clinical picture and also, you know, whether they're obstructed or not can also play a role and also whether they're obstructed or not, can also play a role.

Speaker 3:

Very, very good clinical information. Thank you both. As we transition into the end of our 20 minutes with you, fabulous women, we ask a little more personal question, somehow with your passion for Uralis. Maybe I already know the answer to this, but, camille, while we have you, we'll start with you. What is the oldest or the most interesting item on your desk or in your desk drawer?

Speaker 4:

Yeah, I think in my desk drawers I probably have about 100 old swimming ribbons, which is very curious for me because I swam from the time that I was four to the time that I was six and for some reason as you know, ways change and everything those ribbons have stayed. It's funny because I ended up playing soccer from the time that I was about six, all the way through college and and despite, you know, many tournament trophies and t shirts and medals that I may have won during my time playing soccer, those have kind of gone through the wind, but this for some reason, you know that childhood pride of my old swimming ribbons, those stay.

Speaker 3:

I think that's cool. I was suspecting Uralis, of course, like a giant one, or multiple colors or some weird shape or something, but maybe that was transformative for you, like I can do this. Yeah, that's really cool.

Speaker 5:

How about you, rachel? Probably the most interesting thing on my desk, right now at least, is this gift from my dad from a few months ago. It's a book called an Aussie character and patriotic Latvian and it's a. It's a biography. It's quite a good book. It has a lot of pictures, if anyone's interested, and big text, so it's not a very lengthy read, but it's entertaining and I like it. It's basically a book that really centers around the Australian concept of mateship. So, despite my very good American accent, I was born and raised in Australia and so definitely a little bit of cultural reading there, and this mateship is a concept that's really central to Australians and embodies essentially loyalty and friendship and it's quite unique to Australians. So I keep it on my desk.

Speaker 3:

That's great. Again wrong. I was certainly suspecting. I think I even had some of the like goats have these tiny, beautiful little multiple BBs and I think I might even still have some of those.

Speaker 2:

Yeah, I did not know you were Australian either.

Speaker 5:

So yeah, very good American accent.

Speaker 2:

I've mastered it. That's awesome. Well, thank you so much, camille and Rachel Really appreciate you spending your time talking about your manuscript with us today. Thanks so much, camille and Rachel, really appreciate you spending your time talking about your manuscript with us today. Thanks so much. And to our listeners. You can read Camille and Rachel's article and print Javma or using your favorite search engine. I'm Sarah Wright with Lisa Fortier. We want to thank each of you for joining us on this episode of the Veterinary Vertex podcast. We love sharing cutting edge veterinary research with you and we want to hear from you. Be sure to leave us a rating and review on Apple podcasts or whatever platform you listen to.