SummaryA series of studies of coprophagy in mice has been conducted from the viewpoints of behaviour and nutrition. Since it was necessary to prevent coprophagy to investigate its significance, an attempt was made to devise a restrainer.A polyethylene bottle was cut and fixed to the mouse so as to prevent its head from reaching its anus when faeces were excreted. The animals were also housed in cages with floors of larger mesh size in order to let the faeces fall through.
Keywords: Mice; CoprophagyCoprophagy is considered a normal habit in rabbits (Kulwich, Struglia & Person, 1953;Jilge, 1982) and rats (Barnes, Fiala & Kwong, 1963; Daft et ai., 1963), and has been proved to contribute to the animal's nutrition. The significance of coprophagy could be demonstrated provided that nutritional deficiency was produced under conditions in which an animal was prevented from eating its faeces without severe restrictions.Well-established methods known to prevent coprophagy are neck collars for rabbits (Kulwich, Struglia & Person, 1953) and tail (anal) cups (Barnes, Fiala & Kwong, 1963), jackets (Armstrong & Softly, 1966), neck collars (Neale, 1984) or specially designed cages (Geiyer et al., 1947) for rats. We have studied coprophagy in the mouse (Takahashi et al., 1985;Ebino et al., 1986 Ebino et al., , 1987, but were unsuccessful in the application of a neck collar or a tail cup. In the case of the neck collar the head of the animal was always raised upward, and both natural posture and behaviour were
obstructed;When this was improved, the mouse could practise coprophagy. The tail cup often disturbed blood flow and produced ulceration in the tail at the fixation site. These changes were occasionally aggravated into necrosis or resulted in the severance of the tail at the ulcerated site.In this paper we describe a newly contrived restrainer that has been successful in preventing coprophagy in the mouse.
Materials and methods
Manufacture of the restrainerA polyethylene bottle of height 54 mm and diameter 27 mm was cut and used as the restrainer shown in Fig. 1. The diameter of the ring and the length and width of the restrainer were 13-15 mm, 50-55 mm and 20-30 mm respectively. A pair of holes about 1 mm in diameter were made in the posterior portion of the restrainer.
Attachment of the restrainer to the mouseThe ring of the restrainer was applied to the neck of the animal which had been anaesthetized with ether. The fit of the ring round the neck was carefully controlled (Fig. 2). When the ring did not fit well, it was replaced by anothor more appropriate one. A silk suture was used to sew the restrainer to the skin through the two holes, and the restrainer was attached to the subcutis so that it was centred on the animal's back (Fig. 3). In addition, a cyan acrylate binding agent for surgical operation was deposited near the sutured sites to reinforce the fixation. The disinfectant for the silk sutures and needles was 70% alcohol, and that for the skin was 0路2% acrinol.
