The macrostructure and microstructure of the urinary bladder and urethral mucosa in dogs with lower urinary tract diseases.

The aim of the study was to assess the macrostructure and the microstructure of the bladder and urethral mucosa in dogs with lower urinary tract disease as well as to evaluate the usefulness of the WHO/ISUP grading of invasive and non-invasive tumours of the bladder and urethral mucosa. The study was carried out on 37 dogs of different breeds and of both sexes, from 9 months to 15 years old. An urethrocystoscopy and a histopathological evaluation of mucosal biopsies were carried out in all the studied dogs. Cystitis was the most common disease noted during urethrocystoscopy. Chronic active inflammation of the bladder was the most common inflammatory lesion diagnosed in the histopathological examination, while the transitional cell carcinoma was the most common tumour of the bladder. Urethrocystoscopy proved to be a very useful tool in the assessment of macroscopic lesions in the bladder and urethral mucosa in dogs. We also evaluated the type and extent of microscopic inflammatory lesions in the bladder and urethral mucosa using the modified Sydney scale. The WHO/ISUP scale is very helpful in the histopathological classification of canine invasive and non-invasive proliferative lesions in the bladder and urethra.