Stereotypy

Today in veterinary medicine stereotypy and obsessive-compulsive disorders are distinguished because they follow different patterns. Here only a summary can be given, in daily use both behaviours are called stereotypy, that’s why both are discussed together under the expression “stereotypy” in this text.
We call a motion a stereotypy when an animal moves in a special way which has no reference to its environment and when this motion is some kind of anankastic (compulsive behaviour). Often the animals are seen walking the same way again and again, digging in an edge or gnawing at cage bars for hours. The behaviour shown by red-eyed mice swaying their head is no stereotypy. It is the result of the slightly bad sight of these mice.
Stereotypies arise from too small cages. It differs from one species to another and also from one individual to another how long it takes the mice to develop stereotypical behaviour. Some show it already after some weeks, others after months.
The abnormal behaviour is initiated by an interference of the central nervous system.
The longer a mouse shows this behaviour the more difficult is it to get rid of it after improving the environment. Some individuals, who weren’t exposed to the cause of the stereotypy for a longer time stop showing this behaviour soon after moving to a bigger enclosure that meets their needs better. Others, who were exposed longer to the cause, may take more time until loosing this abnormal behaviour. The old pattern can be observed from time to time again and gets lost over a period of weeks or months.
If mice were kept in small, nondescript enclosures, they would probably never loose the abnormal behaviour completely. They may show the old patterns in bigger enclosures, for example there are mice coming from small tanks which pace around in the new enclosure on the length of their old prison even though there would be much more space to run around.
When you get a mouse you don’t know anything of its past, you can guess how it lived by having a look whether it shows signs of a stereotypy or not. If it does, you can suppose that it didn’t have a cage of proper size in its past. Otherwise, if it always lived in an enclosure of a proper size, it definitely won’t show signs of a stereotypy.
Digging in an edge or gnawing at the cage bars for hours are examples for a stereotypy.

Source
University of Gießen (Germany)

Translation
Angelus Noctis
Proofreading
Jedediah