Clinical, histopathologic, cystoscopic, and fluorescence in situ hybridization analysis of proliferative urethritis in 22 dogs

Abstract

BackgroundProliferative urethritis (PU) is a lower urinary tract disease of dogs characterized by frond‐like lesions in the urethra. The etiology of PU is unknown, although an association with bacterial cystitis is reported.ObjectivesDeep‐seated bacterial cystitis is associated with PU, particularly in dogs with neutrophilic or granulomatous inflammation.AnimalsTwenty‐two client‐owned dogs with PU and 5 control dogs euthanized for non‐urinary disease.MethodsIn retrospective analysis, medical records of dogs with PU from 1986 to 2016 were reviewed. Signalment, clinical signs, cystoscopic findings, antimicrobial use, and results of urine, bladder, or urethral tissue cultures, if available, were recorded. Histopathology was reviewed and classified as lymphocytic‐plasmacytic (LP), neutrophilic, LP‐neutrophilic (LPN), granulomatous, or pleocellular. Eubacterial fluorescence in situ hybridization (FISH) was performed on 18 tissue samples (13 cases, 5 controls), with subsequent evaluation of bacterial species.ResultsOf the 22 dogs, 9 had LP urethritis, 6 had LPN, 4 had pleocellular, and 3 had neutrophilic urethritis. Of note, 7 of 13 PU samples were FISH+ for adherent or invasive bacteria; 1 of 5 controls were FISH+ for adherent bacteria. Five dogs had negative urine and tissue cultures when FISH was positive. There was no association detected between the type of urethral inflammation and the results of urine and tissue culture or FISH.Conclusions and Clinical ImportanceThe type of inflammation varied widely in these 22 PU cases. Deep‐seated bacterial urethritis could be contributing to the inflammatory process in some dogs, regardless of the inflammation type. Urine and tissue cultures likely underestimate bacterial colonization of the urethra in dogs.

Retrospective study of proliferative urethritis in dogs: Clinical presentation and outcome using various treatment modalities in 11 dogs

“…Proliferative urethritis affected only female dogs and was associated with complete or partial obstruction. Most affected dogs had a history of UTI (73%), which is consistent with the previous literature 1‐4 . Effacement of the urethral stenosis, either by BD or stent placement, effectively achieved long‐term successful outcome for these dogs.…”

“…Most dogs had a history of a UTI (8/11, 73%). Previous studies have indicated that the inflammatory component of PU is associated with UTI 1‐4 . Only 4 dogs had positive cultures at the time of diagnosis, but 5 of the dogs with negative cultures were receiving antibiotics at the time of sample collection.…”

“…Proliferative urethritis (PU) is an uncommon, inflammatory, and infiltrative disease of the urethra 1‐5 . This condition often is misdiagnosed as urinary tract neoplasia based on its proliferative appearance and obstructive nature 1,2 .…”

“…Dogs with PU typically are female, and are presented for evaluation of pollakiuria and stranguria, most commonly associated with partial or complete urethral obstruction (UO) 1‐3,6 . The underlying cause has not been clearly elucidated, but it is believed to occur frequently with urinary tract infection (UTI) and may be secondary to immune‐mediated inflammation of the lower urinary tract 1‐4 . In a recent study, more than half of histologic samples from patients with PU were fluorescence in situ hybridization positive (FISH+) for adherent or adherent and invasive bacteria 4 …”

“…Another report of 2 female dogs proposed that this condition should be renamed proliferative urethritis, as a more accurate histologic and gross description of the condition 1 . Cystoscopically, cylindrical masses or frond‐like lesions with fingerlike projections protrude into the urethral lumen, giving rise to the term PU 1,4 …”