Rectal prolapse in mice is commonly caused by which common bacterium?

• A. Mycobacterium bovis
• B. Pasturella multocida
• C. Helicobacter spp.
• D. Bordetella bronchiseptica

Answer: (C)

Rectal prolapse in mice is commonly linked to infection by Helicobacter species, which colonize the lower gastrointestinal tract and cause chronic inflammation of the colon and cecum (typhlitis/colitis). This inflammation leads to increased stooling and straining, which can result in the protrusion of the rectum. Among the bacteria listed, Helicobacter spp. is the one most consistently associated with this GI condition in mice, whereas the others tend to cause respiratory disease (Pasturella multocida, Bordetella bronchiseptica) or systemic infections not characteristically tied to this prolapse lesion. In colonies with suspected Helicobacter infection, addressing this organism is a key part of reducing rectal prolapse incidence.