Choosing The Right Main Substrate: Often being presented with so many substrate options along with many often conflicting opinions as to what substrate is best can be pretty daunting, especially to new keepers. Today we’ll go over the basics of what you want in a substrate, which will hopefully make that choice an easier one to make.
Substrates to avoid as the main substrate
Substrates like corncob, sand, coconut fibre (or similarly, peat moss and similar soil substrates), kaytee soft granules, etc are all safe substrates to offer to your hamster. However, should not be used as the main substrate for a variety of reasons, most notably being that these types of substrates offer very poor burrow stability which, given the burrowing nature of hamsters, do not make them optimum main substrate choices.
Some of these substrates are hard & can mould easily (i.e. corncob) and so are best being kept offered in a smaller section where they are easier to monitor & change as required. Soil substrates are generally not recommended to be the main substrate as they dry out very quickly, and can be difficult to maintain in larger areas. Again, all these substrates are fine to offer in smaller, contained areas where they can be easily monitored - just not as the main substrate of the enclosure.
What makes a quality main substrate
A quality main substrate should be: Low dust. No added scents, these are highly concentrated than say, sprinkling flowers & herbs throughout the enclosure, and can be very overpowering to your hamsters respiratory system. Offer good burrow stability (mixing hay in-between layers is also advisable, as this offers even more stability acting similarly how roots would in the wild).
If using wood based substrate, it should ideally be small flakes, and not very large ones. Larger flaked shavings are often very poor at offering burrow stability. Offer appropriate absorption + odour control. (simply using shredded tissues or newspapers will not offer appropriate absorption).
Examples of safe substrate types
- Aspen wood shavings, smaller flakes if possible.
- Birch wood shavings.
- Non-scented paper based substrates (i.e. uber, boxo, kaytee). Use CareFresh with caution as there appears to be poor quality control, with many batches being too dusty for safe use.
- Hemp (this can be not so great at holding burrows).
- Spruce wood shavings such as Allspan for reasons we will discuss why on the following slides.
Out of all brands mentioned, Allspan is arguably the best substrate for burrow stability. Wait, spruce? That’s a softwood. Isn't all softwood terrible for hamsters?!
Softwood shavings have been repeatedly claimed to be dangerous due to phenols that are present in softwood shavings being a known respiratory irritant. But there is nuance: different species of softwood have varying phenol levels. Spruce has exceptionally low phenol levels, comparable to hardwoods like aspen, according to research on substrate phenol content.
A study demonstrated that barbiturate sleep times for mice kept on hardwood, pine, spruce & cedar substrates showed that spruce had phenol levels that are so low as to be comparable to hardwoods. This suggests spruce is unlikely to cause respiratory issues at typical exposure levels. Fir/spruce mixes may dilute phenol levels further, making them potentially safe depending on composition. Allspan being 100% spruce is considered absolutely safe for small animals in the context of typical home use, though occasional individual sensitivity can occur with any bedding type.
Phenols are a respiratory irritant at high concentrations. There is no 100% dust- or phenol-free substrate. The dose makes the poison, and phenols have been shown to be a concern mainly in high concentrations. Abietic acid, a resin component found in some coniferous woods, is also a respiratory irritant in certain exposure scenarios, particularly in industrial settings with heavy exposure. However, traces in bedding are typically limited and often reduced during manufacturing.
In practice, a safe approach is to choose spruce or spruce/fir mixes with a majority spruce content, monitor for respiratory signs, and provide deep bedding that supports burrowing while avoiding overly dusty products. Updates from manufacturers (e.g., Chipsi indicating 70-75% spruce content) support the safety of these products when used as directed. Always observe your individual hamster for signs of allergy or distress and be ready to switch substrates if needed.
Practical considerations and caveats
No draughts or damp - make sure they aren't exposed to draughty or damp conditions. Predictable light - hamsters need to be kept in a room where the lights go off at more or less the same time each night. Try to avoid erratic hours of lighting. No ultrasound - hamsters should be housed away from household objects that can generate ultrasound, such as televisions, computer screens, vacuum cleaners or sources of running water.
A suitable home cage - wild hamsters live in deep burrows and naturally build nests. Always provide your hamster with a suitable home-cage which allows for a thick layer of appropriate bedding and nesting material. The cage should be safe from hazards and secure. Plastic cages are better than metal, but wooden cages shouldn’t be used. A cage with stainless steel bars or mesh sides is preferable to one with solid sides, and it should have a raised lid. The cage floor should be solid to allow for bedding material to be provided, to absorb the relatively small quantities of urine hamsters produce. Avoid wire mesh floors as they can lead to foot problems.
Don’t use nesting materials that can separate into thin strands such as cotton wool or similar ‘fluffy’ bedding products, as they pose a serious risk to the health and welfare of your pet. The thin strands can be difficult to break, potentially leading to a hamster becoming tangled up in their bedding or other injuries.
Shelters, cage cleaning, and bedding depth
Shelters - Always provide your hamster with a suitable place to hide. For hamsters housed in pairs the number of hiding spaces should exceed the number of animals by one. In addition, provide a nesting box which is sufficiently large for your hamsters to set up a larder, to sleep and to comfortably move around. This shelter should be dark inside and may have an angled entrance to prevent light entering it. Place the nesting box near food and nesting material, but away from water to avoid flooding from leaks. A floorless nesting box helps you check on your hamsters more easily.
Cage cleaning - Make sure your hamsters’ cage is clean with dry bedding and nesting material. Deep clean once or twice a month is typical, with spot cleaning every few days to remove soiled bedding, uneaten food, and faeces. Clean out when the hamsters are awake to minimize stress. Do not let bedding become damp or smelly. Transfer a small amount of old unsoiled bedding during cleaning to maintain scent markers. Replace soiled objects to avoid triggering fighting. Bedding depth supports natural burrowing behavior; studies show deeper bedding encourages burrowing and related activity, contributing to a happier, less stressed hamster.
Bedding recommendations and options - Paper-based bedding is generally considered among the safest options. CareFresh and similar products hold burrow structures well. Aspen can provide good absorbency and odor control but may not hold burrows well on its own; combine with paper bedding for tunnel stability. Spruce bedding is safe due to low phenol levels; Chipsi Classic is a spruce/fir mix with around 70-75% spruce content, kiln-dried to dilute phenols. Some hamsters may be allergic to wood in general, so monitor for respiratory signs, skin irritation, or fur loss. Hay can be layered to help hold burrow structures. Soil can add a natural environment; coco soil from pet shops is common and safe when placed in a designated dig area. Sawdust is strongly discouraged due to fine dust that can cause respiratory infections; cedar contains plicatic acid and is toxic in many contexts; pine and cedar can cause respiratory issues in hamsters. Scented bedding and fluffy materials can cause irritation or ingestion hazards; avoid nesting materials that separate into threads or fluff. Corn cob bedding should be avoided as it molds easily, can lead to obesity if eaten, and is not ideal for burrow stability.
Summary of practical recommendations
Choose a substrate with low dust, good burrow stability, and effective absorption/odor control. Spruce-based or spruce/fir mixes with predominantly spruce content are generally safe, with Allspan (100% spruce) highlighted as particularly stable for burrows. Avoid substrates that mold easily, are overly dusty, or contain added scents. Maintain a deep bedding layer to encourage natural burrowing, provide safe nesting options, and conduct regular, gentle cage cleaning to minimize stress while preserving natural behaviors.
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Table: Substrate types at a glance
| Substrate | Burrow Stability | Dust/Dustiness | Phenol Level | Notes |
|---|---|---|---|---|
| Aspen shavings (small flakes) | Good with depth | Low | Low | Widely recommended; combine with paper bedding for structure |
| Birch shavings | Good | Low | Low | Safe option |
| Spruce shavings (Allspan) | Very good | Low | Low | Arguably best for burrow stability |
| Spruce/Fir mix | Good to excellent | Moderate | Low to moderate | Detrimental largely if high fir content; risk diluted with spruce |
| CareFresh/paper-based | Moderate to good | Low to moderate | Low | Good for burrows when layered correctly |
| Corn cob | Poor | Low to moderate | Low | Molds easily; not ideal as main substrate |
| Sawdust | Poor | High | Variable | Not recommended due to respiratory risk |
Note: While research and field reports support the general safety of spruce and spruce/fir mixes, there remains individual variation in hamster responses. Always observe for signs of respiratory distress, skin irritation, or fur loss, and be ready to switch substrates if adverse signs appear. Abietic acid is primarily a concern in occupational or high-exposure contexts; typical household bedding residues are typically within safe ranges, but monitoring remains prudent.