Spontaneous corneal opacities in laboratory mice

Area of Science:

• Veterinary Ophthalmology
• Laboratory Animal Science
• Toxicology

Background:

• Corneal opacities are inflammatory lesions affecting the cornea in laboratory mice.
• These lesions include ulcers, keratitis, neovascularization, and basement membrane mineralization.
• Incidence varies significantly across mouse strains and microbiological environments.

Purpose of the Study:

• To characterize corneal opacities in laboratory mice (Mus musculus).
• To investigate the incidence of corneal opacities in different mouse strains and housing conditions.
• To identify potential etiological factors and preventive measures for spontaneous corneal opacities.

Main Methods:

• Observation and characterization of corneal lesions in various mouse strains.
• Incidence assessment in barrier-reared, axenic, and gnotobiotic mice.
• Experimental manipulation of cage cleaning frequency to evaluate its impact on opacity development.

Main Results:

• High incidence of corneal opacities observed in DBA/2, C3H, CF1, and BALB/c strains.
• Lower incidence noted in CD-1 and C57BL/6 strains.
• Axenic and gnotobiotic mice exhibited very low incidence (1.6%).
• Twice-weekly cage cleaning drastically reduced opacity incidence.
• Ammonia is proposed as a significant pathogenic factor.

Conclusions:

• Corneal opacities are a common issue in specific laboratory mouse strains.
• Environmental factors, particularly cage hygiene, play a critical role in their pathogenesis.
• Ammonia, a bacterial product, is implicated as a key contributor to spontaneous corneal opacities.