Stephen J. Birchard, DVM, DACVS
Scott Owens, DVM, DACVIM
Polypoid cystitis is a disorder of the urinary bladder in dogs
characterized by inflammation and development of one or more polypoid masses
within the bladder lumen. (Fig. 1)
 |
| Fig. 1: Pedunculated urinary bladder polyps in a dog |
Most affected dogs are female and present
with a history of hematuria or recurrent urinary tract infection (UTI).(1) Several
different species of bacteria have been cultured from the urine of affected
dogs with Proteus spp. being the most common.(1) Polyps tend to be located
cranioventrally in the bladder as opposed to transitional cell carcinoma which tends
to occur in the bladder neck or trigone area. (Fig. 2)
 |
| Fig. 2: Large polyp located in the cranial aspect of the urinary bladder |
It is unknown whether
persistent or recurrent UTI predisposes to polyp formation or if polyps
predispose to UTI. In one study, 7 of 17 dogs with polypoid cystitis also has
cystic calculi.(1) Effective treatment combines surgical resection of the
polyps combined with medical management of the cystitis. Surgical removal of
the polyps is straightforward
if just one or a few polyps are found, especially if the polyps are pedunculated
and not located near the trigone. Widespread polyps are more difficult to
surgically resect, and may require subtotal submucosal resection of the bladder
mucosa.(2) (Fig. 3)
 |
| Fig. 3: Diffuse small mucosal polyps in a dog. |
Alternatively,
use of a Holmium:YAG laser via cystoscopy may be an effective minimally
invasive method of treatment for patients with low numbers of polyps.(3)
Diagnosis
The diagnosis of polypoid cystitis is straightforward in most
cases. Clinical suspicion should
be raised in patients with signs of lower urinary tract disease, including
pollakiuria, hematuria, and stranguria non-responsive to initial therapy. Urinalysis results are non-specific,
with microscopic hematuria seen in most cases along with bacteriuria and
pyuria, the former if an active infection is present. Orthogonal view abdominal radiographs are helpful to rule
out urolithiasis, while characteristic polypoid structures are most commonly
seen via ultrasound of the urinary bladder.(Fig. 4)
 |
| Fig. 4: Ultrasound appearance of a pedunculated bladder polyp (arrow) in a dog with polypoid cystitis |
In the absence of
ultrasound availability, double-contrast cystography may be used. Confirmation can be made via cystoscopy
(Fig. 5) or cystotomy (see below).
 |
| Fig. 5: Cystoscopic appearance of bladder polyps in same dog as in Fig. 4. |
Surgical
Technique
Perform a ventral midline abdominal
approach. After routine exploratory, exteriorize the urinary bladder and
isolate it from the peritoneal cavity with moistened abdominal sponges. Carefully examine the bladder; if the
polyp can be palpated and its point of attachment to the bladder wall
determined, make an initial cystotomy adjacent to this area. (Fig. 6)
 |
| Fig. 6: Large bladder polyp in a dog; cystotomy incision has been made adjacent to the mass to facilitate resection and closure. |
In this
way the entire polyp can be removed by partial cystectomy without making an
additional incision in the bladder. If the polyp cannot be palpated, or there are
multiple polyps present, simply make a routine ventral cytstotomy incision to
expose the polyps. Small pedunculated polyps can be removed by submucosal
resection at their attachment to the bladder. Large polyps with wide mucosal
attachment should be removed by partial cystectomy. (Fig. 7)
 |
| Fig. 7: Excised polyp (P) and full thickness section of urinary bladder (B) |
Prior to bladder closure, obtain a sample of mucosa for culture.
Also be sure to submit all resected tissues for histopathology. Close the
bladder routinely (see Veterinary Key Points blog from 10/11/2014 entitled: Cystotomy for Removal of Cystic and Urethral Calculi in Dogs: Are
you getting them ALL out?).
Postoperative Care
Routine care after cystotomy includes intravenous fluid therapy,
analgesics such as opioids and/or NSAIDS (if renal function is normal), and antibiotics
if indicated. Monitor urinations as well as vital signs. Most animals can be
discharged from the hospital the day after surgery. Post-operative hematuria should be expected, and if severe
the pet owner should be made aware to monitor for urinary obstruction due to
blood clot formation.
Long-term postoperative care depends on results of histopathology
and culture. If polypoid cystitis is confirmed and cultures are positive,
appropriate antibiotics are prescribed for at least 3 weeks, followed by repeat
culture after being off of antibiotics for several days. NSAIDS, including piroxicam,
may be beneficial to reduce inflammation and thereby prevent formation of
more polyps. While this condition
is scarcely reported in the veterinary literature, surgical removal as described
above has a very high long-term success rate. Medical management alone is unlikely to be successful. Partial
resolution of clinical signs may be achievable, but long-term success is
unlikely without surgical intervention.
References
1. Martinez I, Mattoon JS,
Eaton KA, et.al. Polypoid cystitis in
17 dogs (1978–2001). J Vet Intern Med 2003;17:499–509
2.
Wolfe TM, Hostutler RA, Chew DJ, et.al. Surgical management of diffuse polypoid cystitis using submucosal resection in a dog. JAAHA: July/August 2010: 46(4):281-284.
3. Xu C, Zhang Z, Ye H et al. Imaging
diagnosis and endoscopic treatment for ureteral fibroepithelial polyp prolapsing into the bladder. J
XRay Sci Technol. 2013;21(3):393-9.