Colony health checks frequently misdiagnose common integumentary lesions — ringtail, barbering, fight wounds, and ulcerative dermatitis — leading to inappropriate or delayed treatment.

Identify and treat by lesion type: 1) Ringtail (concentric hyperkeratotic constriction rings on the tail) is linked to low ambient humidity; correct by raising room humidity rather than treating the tail directly. 2) Barbering (patchy fur/whisker loss from overgrooming by a cage-mate) needs no treatment unless skin is ulcerated; reduce recurrence with added environmental enrichment. 3) Fight wounds are common in co-housed males of BALB/c, SJL, and FVB strains; remove the aggressor, treat with systemic/topical antibiotics and analgesics, and prevent recurrence by housing littermates only or single-housing aggressive strains. 4) Ulcerative dermatitis, common in C57BL/6 mice, responds to systemic/topical antibacterial treatment aimed at the secondary skin infection driving the lesion.