Retrospective Evaluation of Nail Trimming as a Conservative Treatment for Ulcerative Dermatitis in Laboratory Mice

Abstract

Ulcerative dermatitis (UD) is an idiopathic disease that affects C57BL/6 mice and those having a B6 background. The hallmark of UD is pruritus, which leads to self-mutilation and epidermal ulceration typically in the intrascapular region. Although several treatments for UD have been published, some involve the use of pharmacologic agents that might confound research results. In this retrospective study, we evaluated nail trimming to determine whether this conservative treatment approach improved the resolution rate of UD at our institution compared with that of untreated mice or those that received oral or topical antibiotics. Our findings show that the incidence of resolution of UD was significantly greater and that the time to resolution was shorter in mice treated with nail trimming compared with other groups. These findings support the use of nail trimming as an effective conservative treatment option for UD in B6 mice.

Figure 1.

Technique used for nail trimming. (A) Materials used include a pet nail trimmer and a 50-mL conical tube. Note the air holes at the end of the tube. (B) Mouse is placed head first into the conical tube, to permit easy access to the rear toenails. (C) Once the mouse is restrained within the conical tube, the dominant hand can be used to carefully trim the sharp point of each nail.

Figure 2.

Kaplan–Meier estimates of resolution of ulcerative dermatitis in mice treated by using 1 of 4 methods: nail trim (n = 125), observation (n = 74), oral antibiotic (n = 23), and topical antibiotic (n = 12). Censored subjects are indicated on each curve by using the corresponding tick mark. Time to resolution (log-rank test) was significantly greater in the nail trim treatment group when compared with observed cases (×, P < 0.0001), oral antibiotics (+, P = 0.0003), and topical antibiotic (#, P = 0.0018).

Figure 3.

Resolution of ulcerative dermatitis in a C57BL/6 mouse treated with nail triming. All images are of the same mouse. On day 1, the mouse presented with a pruritic, ulcerated intrascapular lesion; hindlimb nail trimming was performed. By day 4, the mouse was no longer pruritic, and the skin showed signs of healing. By day 7, the ulcerated skin appeared to be healed, and hair regrowth was noticeable. On day 16, hair regrowth was nearly complete.