Cages and all facilities used to secure rats must be constructed and maintained to reduce the risk of injury and attack by predators.
Rats are typically kept in intensive conditions provided the following conditions are met:
- A minimum floor space of 400cm2 should be provided per animal for animals under 450g
- A minimum floor space of 800 cm2 should be provided per animal for animals above 450g
- Minimum height of cage must be 25 cm
- The diet composition and quantities of feed must be recorded
- A nesting and hiding area must be provided
- A high level of hygiene and cleanliness must be kept at all times
- Environmental enrichment must be provided to enable natural behaviours
- Faeces and urine accumulations must be removed twice a week
- Normal diurnal pattern of lighting must be provided with periods of dark
- Opportunities for appropriate exercise must be provided
- Air must be of acceptable quality with respect to dust, chemicals and smells
- All rats must be observed standing and moving during daily inspections.
The environmental requirements of small mammals including rats are complex and must be considered carefully when providing them with a suitable living environment. Rats should never be housed with other species and their cage or nesting place should be regarded as the animals’ home or domain. Rats should never be housed in the same room as potential predators as they will sense their presence.
Movement and Exercise
Caged rats will spontaneously participate in exercise by playing with cage mates, foraging for food, climbing on objects in the cage or using exercise equipment, if provided. However it has been found that rats do not rely on exercise to maintain muscle tone or to work off reserve fat. If exercise equipment is provided for rats, it will usually only be used by young rats and adult females during oestrus. Elevated boxes and tubes made of cardboard or polycarbonate make excellent exercise opportunities for rats.
Natural lighting is always preferred however artificial light with the full range of spectral colors, 45–60 lux is acceptable. Cages should be kept out of direct sunlight. Shelter should also be provided within the cage to allow the rats to avoid light. Students should be able to observe that rats will seek darkness if it is available to them. There should be 12-hour periods of both light and darkness.
As Albino rats are sensitive to light, they should be kept under low light intensity except when being examined. Rats with dark pigmented eyes are more suitable for the classroom.
Bedding used in the rat’s cage should always be highly absorbent dust free, splinter-free, non-toxic, non-edible and not contaminated with pesticides or chemicals. Suggested bedding is sawdust, wood shavings, clean shredded paper, soft cardboard, rice hulls or absorbent paper pellets.
Preferred temperature is 18–22°C. Large fluctuations in temperature should be avoided.
Ensure that there is always good natural ventilation provided for rats.
Rats must always be housed indoors.
Cages should be cleaned regularly, at least twice weekly, then washed in disinfectant and thoroughly dried. New bedding should be supplied and old bedding disposed of in a suitable manner.
Easily shredded materials should be provided. Shredded paper, straw, soft cardboard, paper towels or cotton fibre are suitable. Cotton wool should not be used as it can wrap around the legs of young rats and cause injury. Shredded paper can also cause fine paper cuts in very young un-haired pups.