A new analytical system for quantification scratching behaviour in mice

BACKGROUND: Scratching behaviour is an important component of human atopic dermatitis. The duration of scratching determines the extent of skin damage and thus the rash, but quantification of this is difficult. Establishment of a method for measuring the duration of scratching is important in order to make objective assessments of the factors that may cause the itch and also the efficacy of new antipruritic drugs. OBJECTIVES: A novel method for assessing the duration of scratching in mice was evaluated, based on the time course changes in the distance between the animal's hind limbs and the back of the neck during scratching behaviour. METHODS: Compound 48/80 was administered intradermally to the back of ICR mice and their scratching behaviour was recorded on digital videotape. The distance between the back and the hind limb was measured continuously using an image analysis system. RESULTS: Measurement of the frequency and duration when the mouse's hind limb came into contact with the back of the neck provided an accurate method of quantitating scratching behaviour. CONCLUSIONS: This system provides a new method of quantifying scratching behaviour in a mouse.