Veterinary Surgery May 2026 – Soft Tissue: Feline Cystolithotomy & AGASACA Margin Control

In this Simini Small Animal Surgery Podcast episode, we continue our soft tissue coverage from the May 2026 issue of Veterinary Surgery by examining two studies that challenge surgeons to balance technical precision, patient recovery, and long-term outcomes. 

One study evaluates whether a minimally invasive approach to feline urolith removal truly improves surgical success, while the other explores how microscopic surgical decisions can dramatically alter recurrence risk in dogs with anal sac adenocarcinoma.

In this episode:

✅ Boone et al. — A retrospective study comparing modified percutaneous cystolithotomy (PCCL-M) with traditional open cystotomy in cats undergoing urolith removal. Despite superior visualization, PCCL-M did not improve complete stone clearance, with residual urolith rates similar to open surgery (33.3% vs. 30%). However, PCCL-M resulted in smaller incisions, shorter hospitalization times, and fewer immediate postoperative lower urinary tract signs, suggesting the primary benefit is improved recovery rather than improved stone retrieval. The study reinforces the importance of postoperative imaging regardless of surgical approach. 

✅ Gordon et al. — A retrospective study evaluating the prognostic value of the R margin classification system in dogs with apocrine gland anal sac adenocarcinoma (AGASACA). Dogs with R1 margins experienced a 23-fold increase in local recurrence risk, with recurrence rates rising from 4% (R0) to 50% (R1). Importantly, achieving wider margins that occasionally included portions of the external anal sphincter did not result in a dramatic increase in major complications, supporting a more aggressive surgical approach when appropriate. The study also identified hypercalcemia and lymphovascular invasion as major predictors of poor outcome and metastasis. 

Together, these studies emphasize that surgical success extends far beyond the procedure itself—requiring careful planning, objective postoperative assessment, and thoughtful long-term decision-making.

🎓 Journal Articles Discussed

• Boone et al. — Outcomes and comparison of modified percutaneous cystolithotomy and traditional open cystotomy in 52 cats
• Gordon et al. — Investigation of the “R” tumor margin classification and prognostic factors in apocrine gland anal sac adenocarcinoma of dogs

📚 From the May 2026 issue of Veterinary Surgery

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Transcript

SPEAKER_02 0:04

Hi, I'm Carl Damiani, and this is the Simone Small Animal Surgery Podcast, your fast focused update on what matters most from the latest small animal surgical literature. In each episode, we break down key articles from the veterinary journals and translate them into surgical insight you can use today, not someday. This episode continues our soft tissue coverage from the May 2026 issue of veterinary surgery, and we're focusing on two studies that tackle a fundamental surgical challenge. How do we improve outcomes while balancing technical precision, invasiveness, and long-term patient success? First, we'll look at Boone et al. who compare modified percutaneous systolitotomy with traditional open systotomy in cats undergoing urolith removal. The study explores whether a minimally invasive approach can deliver meaningful advantages in recovery, hospitalization, and postoperative comfort, while maintaining effective stone removal. It's an important paper for surgeons weighing the real-world benefits of minimally invasive urinary surgery. Then we turn to Gordon et al. who investigate the prognostic value of the R-margin classification system in dogs with apocrine gland anal sac adenocarcinoma. Beyond surgical margins, the authors identify several key factors that influence recurrence and survival, offering valuable guidance for surgical planning, client communication, and postoperative decision making in these challenging oncology cases. Two studies, one common theme, surgical success isn't measured only by what happens in the operating room. It's about achieving the right balance between technique, oncologic control, patient recovery, and long-term outcomes. Let's dive in.

SPEAKER_04 1:59

You know, as a busy veterinary surgeon, your time is incredibly valuable. So today's mission for this deep dive is to extract the clinical punchline from a recent surgical study so you can actually apply it in the OR tomorrow.

SPEAKER_00 2:12

Exactly. And today we're looking at a 2026 study by Boone et al.

SPEAKER_04 2:16

Right. So we're talking about a classic clinical challenge, traditional open systotomy in cats. I mean, it's routine, but it comes with that headache of incomplete Uralus removal, right? Trevor Burrus, Jr.

SPEAKER_00 2:27

Yeah, and those frustrating post-op lower urinary tract signs. So the question is, does a minimally invasive alternative like uh modified percutaneous systolithotomy or PCCLM actually fix that problem?

SPEAKER_04 2:39

Aaron Powell Because logically, if you put a high-tech camera directly inside a feline bladder under saline distention, you'd expect near-perfect stone clearance, right?

SPEAKER_00 2:47

Trevor Burrus, Right. You'd think so. But this retrospective study of 52 cats actually proves that assumption completely wrong.

SPEAKER_04 2:54

Aaron Powell Wait, really? The camera doesn't help.

SPEAKER_00 2:56

Not with clearance, no. The quantitative data shows the incomplete removal rates were basically statistically identical.

SPEAKER_04 3:02

Oh wow.

SPEAKER_00 3:02

Yeah. It was 33.3% for PCCLM and 30% for traditional open systotomy.

SPEAKER_04 3:08

Aaron Powell So the minimally invasive method was actually like slightly worse?

SPEAKER_00 3:12

Aaron Powell I mean statistically identical, but yeah, it certainly wasn't better.

SPEAKER_04 3:16

Aaron Powell That is wild. Honestly, if this advanced tech leaves the same or maybe even more stones behind, why would I ever bother pitching a more expensive, complex procedure to a client?

SPEAKER_00 3:28

Aaron Powell Well it comes down to the physical environment. The advanced visualization tech just doesn't change the reality of an obstructed or, you know, highly irritated feline bladder.

SPEAKER_04 3:37

Trevor Burrus Because the bladder wall is so thick.

SPEAKER_00 3:39

Aaron Powell Exactly. Cats presenting with large, firm bladders have acutely thickened inflamed walls, so that inflammation physically obscures the uroliths within the mucosal folds.

SPEAKER_04 3:49

Oh, I get it. So it's like using a high-tech headlamp to find crumbs deep down in the couch. If the cushions are like swollen and tightly wedged together, the light doesn't matter. You're still going to miss things.

SPEAKER_00 3:59

Aaron Powell That is a perfect analogy. Yes. Achieving 100% clearance becomes incredibly difficult regardless of your chosen technique, because the camera only shows you the surface of those swollen folds. Aaron Powell Right.

SPEAKER_04 4:10

It can't see what's trapped beneath them.

SPEAKER_00 4:12

Yeah.

SPEAKER_04 4:12

So which brings me back to my original question. Why bother with PCCLM at all? What's the actual clinical win here?

SPEAKER_00 4:20

Aaron Powell Well, the win shifts from absolute clearance to patient recovery. That's the real benefit.

SPEAKER_04 4:26

Okay, so they bounce back faster.

SPEAKER_00 4:27

Yeah. Significantly. The study found PCCLM resulted in much shorter incisions, reduced hospitalization times, and notably fewer immediate postoperative lower urinary tract signs.

SPEAKER_04 4:39

Aaron Powell Which clients obviously love. Getting the cat home faster, more comfortably is a huge deal.

SPEAKER_00 4:44

Definitely. So the actionable takeaway for your clinic is that PCCLM is a highly viable alternative for patient comfort, but you just cannot let the technology give you a false sense of security.

SPEAKER_04 4:54

Right. Rigorous post-op imaging remains absolutely mandatory. You have to check your work.

SPEAKER_00 4:59

Always. And you know, this actually highlights a much bigger issue in surgery. We tend to trust our standard tools a bit too much.

SPEAKER_04 5:05

Oh, for sure. We assume a cystoscope clears all the stones, just like we assume a standard saline flush clears all the bacteria in, say, an orthopedic closure.

SPEAKER_00 5:14

Exactly. And the data says otherwise on both counts. That blind spot in standard of care protocols is a huge risk factor.

SPEAKER_04 5:20

Aaron Powell Because when you look at orthopedic primary and revision surgeries, saline is the standard, right? But it leaves so much behind.

SPEAKER_00 5:28

Right. Independent head-to-head studies show saline leaves 42% of bacteria behind.

SPEAKER_04 5:34

Wait, 42%? That is a massive amount of bacteria to just leave in a joint or a fracture repair.

SPEAKER_00 5:40

It really is. Saline just lacks the physical properties to dislodge adhered bacteria. It basically just washes over the surface.

SPEAKER_04 5:47

Aaron Powell Which is why Simony Protect Livage is stepping in as the new standard, right?

SPEAKER_00 5:51

Exactly. But just to be perfectly clear up front, this is a tool for orthopedics only.

SPEAKER_04 5:56

Yeah.

SPEAKER_00 5:56

It is never to be used in abdominal soft tissue surgeries.

SPEAKER_04 5:59

Right. So absolutely no using it in the systemies we were just talking about. No body cavities.

SPEAKER_00 6:04

Spot on. But for orthopedics, it's a game changer. It's a 60-second non-antibiotic step right at closure.

SPEAKER_04 6:11

Aaron Powell So how does it actually fix that 42% failure rate if it's not an antibiotic?

SPEAKER_00 6:17

It acts mechanically. It physically lowers surface tension and lifts the adhered bacteria right off the tissue.

SPEAKER_04 6:23

So it can just be completely flushed away.

SPEAKER_00 6:25

Exactly. The data shows it leaves 0% of bacteria behind. It simply removes what saline misses.

SPEAKER_04 6:31

Aaron Powell And it doesn't disrupt the existing workflow, which is great. It really comes down to verifying our assumptions with hard data.

SPEAKER_00 6:38

Aaron Powell Yeah. Relying on a false sense of security compromises patient care. Minimizing those blind spots is how clinical practice evolves.

SPEAKER_04 6:46

Definitely. Like with feline urolithiasis, PCCLM offers a much smoother recovery, provided you verify with imaging.

SPEAKER_00 6:54

Exactly.

SPEAKER_04 6:54

Which leaves us with a final thought for you to chew on today. If acute bladder wall inflammation physically hides uroliths from even a high-tech cystoscope, should the surgical community be aggressively rethinking how we medically manage preoperative inflammation before we ever reach for the scalpel? Turning the page.

SPEAKER_00 7:36

Yeah, it is a staggering number, right?

SPEAKER_04 7:38

It really is. So welcome to this deep dive. If you are a busy, small animal veterinary surgeon, well, this is tailored specifically for you. Our mission today is to translate recent literature into surgical decision-making intelligence you can use in the OR tomorrow. We are breaking down canine apocrine gland, anal sac, adenocarcinoma, or agossica, drawing directly from the article by Gordon et al. 2026. We are tackling that eternical dilemma of getting clean margins without causing devastating perianal complications.

SPEAKER_00 8:09

Right, because it really is the ultimate test of anatomical precision. I mean, you are operating literally millimeters away from structures that entirely dictate a patient's quality of life.

SPEAKER_04 8:18

Aaron Powell Exactly. And in most soft tissue sarconas, we went, you know, wide, generous margins. Yeah. But with Agasaka, we usually rely on the R classification system, which gives us a pretty harsh binary. Like we all know R0 means you have some layer of clean tissue, and R1 means you're right on the tumor, basically a dirty margin. So if a surgeon ends up with an R1 margin, is that genuinely a guaranteed surgical failure?

SPEAKER_00 8:42

Well, the clinical data from the 74 dogs in this study answers that pretty brutally. Uh the surgeons achieved an R0 margin in about 75.7% of cases.

SPEAKER_04 8:52

Aaron Powell Okay, so roughly three-quarters. That's not terrible.

SPEAKER_00 8:55

No, it's not. But here is the real impact of that binary pass or fail grade. An R1 margin increases the odds of local recurrence by 23 times.

SPEAKER_04 9:04

Right, 23 times. You have to put that into perspective for us because that sounds almost unmanageable.

SPEAKER_00 9:08

Aaron Powell It is massive. So dogs with a clean R0 margin had a recurrence rate of just 4%. But for those with an R1 margin, it skyrocketed to 50%.

SPEAKER_04 9:18

Well, 50%.

SPEAKER_00 9:20

Yeah. Half of those dogs saw the tumor return locally just because of that microscopic residual disease.

SPEAKER_04 9:26

Aaron Powell Honestly, when I hear a 50% recurrence rate, my immediate instinct is to just go in and take massive margins. But I mean, staring down at the external anal sphincter and the rectal adventitia, taking wide margins, is terrifying. Aren't we just trading a recurrence risk for, you know, permanent fecal incontinence or severe dehesance? Trevor Burrus, Jr.

SPEAKER_00 9:48

Right. And that is the exact mental hurdle most surgeons face. You know, we don't want to ruin the dog's life. But Gordon et al. Aaron Powell, Jr.

SPEAKER_03 9:58

How so? Do they just accept the risk?

SPEAKER_00 10:00

Aaron Powell Well, the surgeons in the study didn't just shell the mass out, they performed deliberate, wider excisions, taking a one to two millimeter margin that frequently included partial sphincter muscle while uh preserving the rectal adventitia where possible.

SPEAKER_04 10:13

Aaron Powell Okay, so it's almost like skimming the frosting off a cake without disturbing the delicate layers underneath. Like you have to be willing to take a tiny bit of the cake, which is the sphincter here, to guarantee you got all the frosting.

SPEAKER_00 10:24

That is a great way to visualize it, yeah. And despite that more aggressive approach, the overall complication rate was only 16.2 percent.

SPEAKER_04 10:31

Aaron Powell Wait, really? Only 16 percent.

SPEAKER_00 10:33

Aaron Ross Powell Exactly. And that is well within the previously reported normal limits for this procedure.

SPEAKER_04 10:38

Aaron Powell So taking that extra tissue didn't actually spike the severe complication raise at all.

SPEAKER_00 10:43

Not at all. I mean most complications were just minor surgical site dehesance. Only two dogs out of the entire cohort experienced long-term fecal incontinence.

SPEAKER_04 10:52

Aaron Powell That is a huge relief. So the clinical relevance here is clear. Basically, don't under-resect out of fear.

SPEAKER_00 10:59

Aaron Ross Powell Precisely. Aiming for that R zero margin is highly feasible and it does not doom the patient to a terrible quality of life.

SPEAKER_04 11:06

Aaron Ross Powell Right. So securing that R zero margin solves the local problem. But we know Agasca is notoriously systemic. How often are these dogs actually dying from the primary mass versus, say, metastasis or systemic fallout?

SPEAKER_00 11:18

The systemic picture is really what ultimately dictates survival. So overall, the median survival time was 25 months.

SPEAKER_04 11:24

Aaron Powell Okay, but two years.

SPEAKER_00 11:26

Yes. But if a dog presented with preoperative hypercalcemia, that survival time plummeted to just 7.5 months.

SPEAKER_04 11:34

Wow, that is a drastic drop. Because that preoperative hypercalcemia isn't just, you know, a red flag on blood work, right? It's a marker of a highly aggressive perineoplastic phenotype pushing PTHRP.

SPEAKER_00 11:47

Unquestionably. I mean, the tumor biology is already systemic before you even pick up a scalpel, and the histopathology confirms this aggressive behavior.

SPEAKER_02 11:54

In what way?

SPEAKER_00 11:55

Well, if the report shows lymphovascular invasion, the tumor has essentially built a highway directly to the sublumbar lymph nodes, and that increases the odds of metastasis by 8.3 times.

SPEAKER_04 12:06

8.3 times, cheese. Which actually brings up a really fascinating anatomical nuance from the study. Over 10% of these dogs either already had or later developed contralateral agusca.

SPEAKER_00 12:17

Yes, that was a crucial finding. Meticulously monitoring that supposedly normal opposite anal sac is completely non-negotiable.

SPEAKER_04 12:24

Right. You really cannot afford to tunnel vision on the disease side when bilateral disease is such a documented threat.

SPEAKER_00 12:30

Exactly. You have to look at the whole patient context.

SPEAKER_04 12:32

Aaron Powell So let's distill this into actionable intelligence for the OR tomorrow. First, ink confidently for those R0 margins. The data shows you can take that millimeter of sphincter without a catastrophic spike in complications.

SPEAKER_00 12:45

Right. Do not be afraid of the anatomy.

SPEAKER_04 12:47

Exactly. Second, aggressively stage those sublumbar lymph nodes, especially if you see lymphovascular invasion. And finally, always, always check the opposite anal sac.

SPEAKER_00 12:59

Yeah, those are the perfect takeaways. But there is one final, almost philosophical data point from the study to leave you with. The data revealed that older dogs actually had significantly lower rates of local recurrence.

SPEAKER_03 13:12

Wait, lower? That is so interesting.

SPEAKER_00 13:14

Right. It leaves you wondering if older patients simply have less aggressive tumor biology.

SPEAKER_04 13:19

Or unfortunately, do they just not survive long enough for that 23 times recurrence risk to catch up with them? Just something to mull over before you make your next incision.

SPEAKER_01 13:31

That's it for this episode of the Semini Small Animal Surgery Podcast. This show is brought to you by Semini Protect Livage, our interoperative lavage developed to target resistant bacteria and biofilms where traditional solutions of saline and post op antibiotics fall short. If you're interested in learning more or trying out your own procedures, you'll find information and links in the show notes. Thanks for listening, and we'll see you in the next episode.