Rat Enrichment: It Is the Number of Types That Matters

Rats have more enrichment research behind them than almost any other pet species, and the most useful finding for a pet keeper is not about any particular product.

What the Research Says

The deep background is a 2022 systematic review in Frontiers in Veterinary Science covering environmental enrichment for laboratory rats and mice. It found both benefit similarly from enriched living environments, with no evidence that housing conditions affect the welfare of different strains differently.

The more directly useful paper is an exploratory study of pet rats and their husbandry conditions. It found that a greater total number of enrichment types, listed as nesting material, digging substrate, foraging device, climbing structure, tube, hideaway and suspended area, was associated with more frequent digging, nesting and climbing, all natural behaviors.

The Seven Categories

Work through them rather than buying more of what you already have.

Nesting material. Paper, fleece strips, tissue. Rats build, and material to build with is one of the highest-value cheap items in rodent welfare generally.

Digging substrate. A tub or a deep corner of loose material they can excavate.

Foraging device. Something food has to be worked out of. A wooden foraging puzzle solves a lid, a snuffle mat makes it scent-led searching instead, and scatter feeding does a version of the same job for free.

Climbing structure. Ropes, ladders, branches. Rats climb constantly and a cage with only floors is half a cage.

Tube. Connected cover that lets a prey animal cross open space.

Hideaway. Enclosed sleeping spots, more than one, so a group is not competing for the only dark place.

Suspended area. Hammocks and platforms. Rats sleep off the ground given the option.

Social Housing Comes Before All Seven

None of the above substitutes for another rat. These are intensely social animals and single housing is a welfare problem that enrichment does not solve. Two is the minimum, a small same-sex group is better, and a cage that fits a group is the first purchase: the minimum floor size and the bar spacing that keeps a rat inside it are what to check before buying. A multi-level rat cage gives them the floors.

Training, Which Rats Are Unusually Good At

Rats learn target training, recall and short trick sequences quickly, and a clicker and target stick is the whole kit. A few minutes daily is cognitive enrichment, exercise and relationship-building at once, and it is free. This is a species where the interaction genuinely is enrichment and not a stressor, which is not true of most small pets, mice included.

The Wheel, in Proportion

A correctly sized solid-surface wheel is a fine addition. Solid surface, never wire or mesh, which injures feet, and large enough that the back stays flat. It is one category of seven, not the centrepiece.

Priority Order

1. Companions, before anything else
2. A cage large enough for a group with multiple levels
3. Coverage across all seven enrichment categories, not depth in one
4. Scatter feeding instead of a bowl
5. Daily out-of-cage time and training
6. A correctly sized solid wheel
7. Rotation and novelty, ongoing instead of last

What Not to Do

Do not keep a single rat. Do not buy a better version of a category you already cover while leaving three uncovered, since the study measured breadth. Do not use a wire or mesh wheel, or one small enough to arch the spine. Do not use cedar or pine shavings, which cause respiratory problems in a species already prone to them. And do not treat scatter feeding as a substitute for a proper ration.

Sources & Further Reading