Pathologic copulatory lock in a genetically engineered laboratory mouse breeding pair

Area of Science:

• Veterinary Medicine
• Reproductive Biology
• Rodent Research

Background:

• Copulatory locks (coital ties) and copulatory plugs are documented in some rodent species.
• These phenomena have not been previously reported in laboratory mice (Mus musculus).

Purpose of the Study:

• To report a novel case of copulatory lock in laboratory mice.
• To investigate the potential cause and consequences of this event.

Main Methods:

• Observation of a breeding pair of genetically engineered laboratory mice in apparent copulatory lock.
• Gentle separation of the pair under anesthesia.
• Physical examination and histopathological analysis of affected tissues (penis, vagina).

Main Results:

• A vaginal prolapse was noted in the female; the male exhibited penile necrosis and a distended bladder, leading to euthanasia.
• Histopathology confirmed coagulative necrosis of the distal penis.
• A firm, cylindrical mass consistent with a copulatory plug adhered to the glans penis.

Conclusions:

• This is the first reported instance of copulatory lock and associated penile necrosis in laboratory mice.
• The adherence of a copulatory plug to both the penis and vagina is hypothesized to have caused the lock and subsequent ischemic necrosis.
• This case highlights a potential reproductive complication in laboratory mice.