Tunnels are a key feature for the tunnel method of refined mouse handling. They come in many materials like polycarbonate, ideal for biosecurity and autoclaving, and pulp paper tunnels that are more easily acquired. Considerations for acquiring tunnels, care and cleaning, and additional factors to consider when using tunnels are reviewed below.
*Clear polycarbonate is recommended as clear tunnels allow for easy visualization of mice within the tunnel.
high temp polycarbonate
30 x 50 mm, 3 mm wall thickness OR
00 x 50 mm ID 3 mm wall thickness
YES
Does your company sell tunnels but you don’t see your product listed here? Reach out to info@na3rsc.org to add your product.
Some facilities already house their mice with huts. If your facility has access to huts, this can be a practical and effective way to implement refined handling.
As with tunnels, huts come in a variety of designs, and your choice may be limited by what is already available in your facility. However, some hut designs are more suitable for handling than others.
When selecting a hut to support ease of handling, consider the following design features:
high-temp polycarbonate
4 1/4″ diameter x 2 1/4″ tall
with 3 openings – 1 1/4″ wide x 1 3/4″ tall
YES
high-temp polycarbonate
4-1/2″ x 4-1/2″ x 2″ high, 3 openings at the top and 1 at the bottom
NO
unprinted, uncoated white book publisher-grade paper
Length: 5.75″
Width: 3.25″,
Height: 2.5″
NO
Refined handling can also be compatible with high biosecurity laboratories and facilities. For highest biosecurity, home cage tunnels or huts and sanitizing gloves between cages is recommended. Often institutions will mimic similar biosecurity procedures as used for previous handling procedures. For example, if forceps and a forceps bath was used previously, they may use a hand bath instead. Recent evidence has shown that home cage tunnels and huts are preferred by mice from the outset, but habituation to a novel handling object is possible after just a few brief handling sessions (Bodnar et al., 2025).
A number of tips are listed below based on the successful implementation of this technique in current facilities:
* In Biohazard colonies where hands are not allowed to touch the animals, a tunnel or hut can be used instead and kept in the homecage (see below) or a sterile supply can be kept in the colony room.
Check out our refined handling course which contains more information about using refined handling while maintaining biosecurity, by clicking the link here.
How you clean your tunnels can vary based on the manufacturer’s recommendations (e.g., autoclaving vs cage washing). Typically, reusable tunnels are made of autoclave- and cage washing-safe material, like polycarbonate. Most tunnels are sanitized 1x/month.
For washing, tunnels are scrubbed as needed, placed in a single layer, and inspected for cleanliness. Excessively soiled tunnels can be soaked in plastic bins.
Many facilities will likely already have a protocol for washing huts. If not, they can easily be stacked (more easily compared to tunnels), and many can be autoclaved or cage-washed, depending on the brand.
An example of tunnel arrangement for autoclaving can be seen in the photo to the right.
Colored polycarbonate: colored tunnels & huts (e.g., red or yellow) allow for low-light shelter for your mice, while still allowing for health observation.
Cardboard/recycled paper: cardboard tunnels & huts are disposable (and therefore do not require additional cleaning/sanitation). They also provide mice with a source of sheltering, nesting, and gnawing enrichment, and can help reduce boredom or aggression. However, they can obstruct health observations by animal care staff and must be replaced much more frequently than reusable tunnels or huts.
Lifespan/replacement: Most tunnels & huts (plastic/polycarbonate) last about 3 years.
Tunnel size: you want to be sure your tunnels or huts are large enough to fit your mice, but small enough to fit in the cage and not get stuck.
Home cage tunnels & huts: home cage tunnels & huts are not necessary, but have many benefits, including:
Flooding concerns: Improperly placed tunnels or huts can cause automatic watering systems to run, therefore increasing the risk of flooded cages. However, valves can be replaced with a newer design to prevent floods, and properly placed tunnels or huts can reduce this risk.
