Rethinking Equine Cystitis: Evidence from Four Atypical Clinical Presentations.

In this case series, four equines were diagnosed with cystitis, resulting in divergent clinical outcomes. Three animals achieved complete clinical resolution without recurrence, whereas one required euthanasia due to progressive clinical deterioration. All diagnoses were established through a dual-modality investigative protocol comprising cystoscopic evaluation and histopathological examination of bladder mucosal biopsies. The cohort exhibited considerable etiological heterogeneity. One case was classified as chronic idiopathic cystitis, while another was attributed to an opportunistic bacterial infection involving Facklamia spp. A third case demonstrated histopathological features consistent with mild chronic-active inflammation, characterized by mucosal hyperplasia and focal ulceration. Of particular pathological significance was one equine presented with marked epithelial denudation accompanied by pronounced submucosal edema, notably in the absence of appreciable inflammatory cellular infiltration. These characteristic morphological features and lesions observed in the horses share certain histopathological features with inflammatory bladder lesions described as interstitial cystitis in other species. However, these conclusions should be interpreted with caution, as the findings are based on only four horses.