Lanolin as a treatment option for ringtail in transgenic rats.

Ringtail is a condition characterized by dry skin and annular constrictions that sometimes result in loss of portions of the tail. This condition most commonly affects preweanling rats, and low relative humidity is thought to be a principal cause. The use of transgenic rats in our facility has been increasing since 2002, and we recently diagnosed several litters from transgenic Fischer 344 rats (Rattus norvegicus) with ringtail. Treatment was necessary to maintain the health and integrity of the tails to allow genotyping. Lanolin ointment was chosen because it is a nontoxic, inexpensive, effective moisturizer used for treating human skin conditions. We examined 5 litters comprising 37 pups total, ranging in age from 7 to 17 days at the time of presentation. Animals in 3 litters were randomly assigned to a treatment or nontreatment group, and all animals in the remaining 2 litters were treated. Lanolin was applied to the tails of treatment groups once daily for 6 d. Treatment was tolerated well by pups and no animals were rejected by the dams. After treatment, tail condition was scored from 0 to 3, with 0 representing a tail normal in appearance, and 3 representing severe disease. Chi square testing showed marginal statistical significance, with a trend for a higher percentage of treated rats having healthier tails on day 7 compared to untreated pups. The Pearson correlation between treatment and tail condition scores was significant. Results indicate that lanolin was an efficacious treatment option for ringtail.