Evaluation of chromocystoscopy in the diagnosis of cystitis in female donkeys

Early detection of cystitis in equine is essential to improve the prognosis and outcome of therapy. However, the conventional white light endoscopy is not sufficiently accurate for this purpose. Hence, this study evaluated chromoendoscopy as a recent diagnostic tool for cystitis in female donkeys. For this purpose, 5 apparently normal donkeys (control group) and 5 female donkeys with cystitis (diseased group) were used. Physical and rectal examinations, urine analysis, white light cystoscopy, methylene blue-based chromoendoscopy and histopathology were performed in all animals. Turbid urine exhibiting an alkaline pH and a significant (P = .02) increase in the numbers of RBCs and WBCs was observed in the diseased group compared to the control one. In the control group, white light cystoscopy showed a smooth pale pink glistening mucosa with two openings of the ureters and visible submucosal blood vessels. During chromocystoscopy, faint bluish discoloration of the mucosal surface with clearly visible submucosal blood vessels was detectable. These findings were correlated with the histopathological findings of the biopsies collected from the urinary bladder. In the diseased group, white-light cystoscopy showed clearly visible blood vessels, mildly hyperaemic mucosa in focal or diffuse forms and small vesicle formation. Chromocystoscopy revealed dark bluish oedematous and irregular mucosa either in a focal form or a diffuse form (marbled appearance) with deeply stained submucosal blood vessels. Histopathologically, the urothelium was hyperplastic with squamous metaplasia and the lamina propria was infiltrated with few leukocytes and congested blood vessels. Small bluish dots representing the absorbed methylene blue dye were seen in the inflamed areas against the lightly stained mucosa of the bladder. Severe diffuse necrotic cystitis was also seen with bacterial aggregations on the surface. Gram’s staining revealed both gram positive bacilli and Gram positive coccobacilli. In conclusion, chromoendoscopy is a helpful tool for early diagnosis of cystitis in female donkeys and enables targeted biopsies, which improves the prognosis and outcome of therapy.