"The use of hoppers [feeding devices] reduces the fouling of food and cuts wastage due to scattering and they are easy to refill ... Where removable hoppers are used the metal at the edge of the hole it rests in is apt to supply exercise for the teeth of the mice unless it is either reinforced or the whole cage is made of sufficiently stout material"
UFAW (1957), pp. 256–7.

Metal_Back_1

We had all these mice in these great big heavy metal cages. So when you’re handling a lot of those it is quite heavy work, and they’d be full of wood shavings and things like that. It was also extremely noisy, which wasn’t good for the mice. So that was one thing I was concerned about straight away, that the actual cleaning was extremely stressful because of the noise generated by these metal cages, metal scraper scraping them out and everything. \[...] We progressed to aluminium from galvanised zinc, which was much, much lighter, much kinder, and I think a warmer metal for the animals as well.

Metal_Bottom_1

The appeal of mice to biomedical researchers was in the ability to standardise their genetics. Long process of inbreeding made the animals in the same strain nearly uniform, and often very different from the familiar domestic mice. Just like mouse genetics was being standardised in the first half of the twentieth century, so were animal facilities – handbooks, new societies and journals shared best practices, and commercial caging solutions were becoming available. As metal mouse caging took over in the middle of the twentieth century, it offered some clear advantages – mainly the ease of cleaning and disinfecting, and by effectively preventing mice from escaping. At the same time, metal cages were heavy, noisy, opaque, and gave facilities an industrial feeling.

Metal_Front_1

As animal experimentation was being scaled up in the 1910s, this early metal design was promoted on the grounds that "not only might the animals be  cared for conveniently, but the cages be easily cleaned and completely sterilized and the spread of infection prevented."
Lane (1916).

Metal_Left_1

"Taking a detached look at the typical animal house, one is impressed by the amount of time employed by emptying trays and cleaning cages. It is as though one were to retain chamber maids to empty chamber pots in the days of the flush toilet. Why not bring the flush toilet into the animal house? We have done achieved this at very little cost with much saving of time in this most unpleasant of duties"
Lack et al. (1958)

Metal_Right_1

"Many laboratories employ large single mouse cases to hold animals prior to and during experimental use. For many experiments the numbers of animals employed are too small or too large for the small, typical shoe-box cage. Efficient use of space is lost in the first instance. More time is required for animal care by the animal technician in the latter situation. By making several modifications in the large cage frequently used by investigators we have arrived at a mouse cage design which may be used in a variety of ways ..."
Easterday and Schlosser (1958), p. 84.

Metal Housing

How did the animal environment become standardised?