Göttingen minipigs present with significant regeneration kinetics after sphincter injury compared to German landrace...

Animals serve as important models for exploring the pathology, diagnosis, and therapy of different diseases and injuries. While smaller animals are preferred for bulk cohort studies, larger animals offer opportunities to investigate surgical procedures at proportions close to the human situation. Therefore, in a feasibility study, we investigated urethral sphincter deficiency in German landrace gilts and Göttingen minipigs to develop a model of urinary incontinence as a basis for future preclinical studies of incontinence therapies. Urethral sphincter deficiency was induced surgically by transurethral electrocautery and balloon dilatation, and the deficiency was determined by urodynamics after injury and during follow-up. In cryosections, sphincter injury was visualized by histochemistry.

Sphincter deficiency was induced in two cohorts and groups of four female Göttingen minipigs each (total n = 20) by two different treatments. One cohort of minipigs showed an initially significant urethral sphincter deficiency (treatment 1; n = 16, p < 0.001). However, spontaneous sphincter regeneration was observed within one to two weeks. The other cohort of minipigs (treatment 2; n = 4) displayed a non-significant reduction of urethral sphincter pressure and an increase in muscle strength over time as well. In contrast, German landrace gilts presented immediately after treatment with significant sphincter deficiency (treatment 1; n = 6, 21%, p < 0.001) and suffered from significant loss of sphincter function for at least five weeks (67%, p < 0.01).

Göttingen minipigs inherit significantly superior sphincter regeneration capacities compared to landrace pigs. This difference may bias preclinical studies in urology and other fields and explain in part seemingly contradictory results from different animal studies.