A mouse having its nails trimmed. Photo credit: Sean Adams
Many of us can attest to the rejuvenating effects of a manicure or a pedicure. The same applies to mice, as recently determined by Stanford University School of Medicine researchers. The investigators report that a simple pedicure can treat ulcerative dermatitis, a ubiquitous and often fatal condition among laboratory mice.
UD affects up to 21 percent of lab mice. Its specific cause remains unknown, although strong evidence suggests that it is behavior-related. Deep, itchy lesions often appear first on the neck. These lesions spread as the mouse scratches itself. UD is currently the most common cause of unplanned euthanasia among lab mice.
In a PLoS ONE paper, Sean Adams’ group described nail trimming as an alternative to the laborious and ineffective application of daily ointment to treat UD. This method was the first of several anecdotally-reported strategies that the researchers planned to explore. A pedicure, they found, reduces animal suffering, saves time and money, and boosts the integrity of mouse studies by reducing the need for medical intervention. Fewer euthanized mice means fewer mice needed per study.
A device used to restrain mice while their nails are trimmed. Photo credit: Sean Adams
The investigators then carried out a study. In one 14-day trial, 93.3 percent of mice were cured of UD with a pedicure compared with 25.4 percent of mice treated with daily ointment. The nail-trimmed mice received a one-time dose of topical treatment to prevent bacterial growth and soothe inflammation. These mice resisted scratching even after their nails grew back. “By intervening in the itch-scratch cycle, we are giving the animals the time that they need to recover, and also perhaps for that behavior to ramp down,” says Joseph Garner at Stanford University, a coauthor on the study.
The researchers later devised a plastic restraint, a modified conical tube, to keep the mice still while their nails are trimmed. With training, this process can take as little as 30 seconds. The researchers have been distributing these tubes when they present their findings at conferences, hoping to encourage more labs to adopt this humane and economical practice.
“There was a lot of serendipity and luck involved,” says Garner. “We never expected that we would find a solution that works in such a high percentage of mice, that it would be so simple, or that we would find it on the first try.”
Alexandra Taylor (ataylor@asbmb.org) is a staff science writer at ASBMB and a master’s candidate in science and medical writing at Johns Hopkins University.