Rectal prolapse in mice is most commonly associated with infection by which genus?

• A. Mycobacterium
• B. Pasturella
• C. Helicobacter
• D. Bordetella

Answer: (C)

Rectal prolapse in mice is most strongly linked to infection with Helicobacter species, especially Helicobacter hepaticus. This genus colonizes the lower gastrointestinal tract and triggers chronic active colitis and typhlitis, causing diarrhea and straining that can lead to the rectum protruding. In laboratory colonies, this association is a classic finding when Helicobacter infection is present, often in aging or immunocompromised animals. Other organisms listed tend to cause disease in different systems—mycobacteria produce granulomatous disease, while Pasteurella and Bordetella are primarily associated with respiratory infections—so they are less likely to be linked to prolapse. Prevention and control rely on surveillance for Helicobacter, confirmation by histology or PCR, and colony-wide management to eradicate or limit infection rather than relying on treatment of individual animals.