It depends on the type of pet because the bedding/litter usually contains some of the pet’s waste – poo and whatnot. It’s not recommended to compost the faeces of animals that eat meat (or fish), or that hunt or otherwise eat random bits of food because it is considerably more likely to contain dangerous organisms that aren’t broken down in the composting process. (It’s especially important not to compost that type of poo if you’ll be using your resulting compost on a veg bed or for other edibles.)

However, it’s ok to compost the waste of healthy vegetarian animals (such as rabbits and some pet rodents & birds) so assuming the bedding is made from natural products and 100% biodegradable (such as straw, shredded paper or wood shavings from a safe source), you can throw it all on the compost heap: the bedding, the poo, any bits of food that have been scattered about and any shed hair/fur.

Liners for the bottom of cages/hutches etc of vegetarian animals can be composted too if they’re made from paper or other natural materials. Don’t compost plastic ones unless they explicitly state they can be composted – biodegradable plastic is not the same thing: it will not become humus and may leave plastic remnants in your heap for a long time.

Well-rotted horse manure is a prized natural fertiliser amongst gardeners – as it’s a great soil conditioner and is usually freely available from stables or livery yards. Well-rotted horse droppings have the advantage over fresh ones because the nutrient levels in fresh can sometimes be a little “hot” (which can damage tender roots) and because the decomposition process makes seeds from grasses and weeds less likely to resprout.

Well-rotted horse manure is achieved by, well, leaving it to rot for a while – usually six months to a year. Some people stir it into their regular compost heap but because of the amount of “product” their horses generate, most horse owners have dedicated piles for the poop.

A pile of pure poo will take a lot longer to break down (and be smellier in the meantime) than one that is balanced in composting terms: manure needs to be balanced out with dry “browns” such as newspaper, cardboard – or, most conveniently, things like straw or woodshavings that are typically used as bedding in stables.

Whether it is wheat, barley or oat, straw will rot down quickly in a moist compost heap – the moisture can come from horse wee & poo (such as you’d get in their bedding) or if it’s a bit dry, from water (dregs from troughs is fine). The same applies to wood shavings, fibres and wooden pellets used for bedding.

A horse poo and bedding compost heap will benefit from turning during the composting process – once a month is ideal. This will help preserve airflow as well as making sure matter from the compost of the heap has some time in the warmer centre. (If you are unable to turn it, at least jab it with a garden fork or a stable/manure fork to help with aeration.)

As meat (and random stuff) eaters, cats’ faeces contain all sorts of nasty bugs and dangerous organisms that you don’t want mixed in with your compost – particularly if you’re going to be using it on your veg bed. Although it’s tempting to add wood-based or paper-based litters to the heap (since they do break down quickly), it’s best to avoid anything that has come into contact with that potentially problematic poop.

(Wee is not such a problem – healthy urine is typical sterile – but the clumped litter might have come into contact with faeces at some point.)

If you’d rather not send it to landfill and have the space, you may want to explore a dedicated pet poo bin: dug into the ground and treated regularly with proprietary product (some are harsh chemicals, some are kinder to the environment), they break down poo quickly and without stinking up the place. Make sure you pick a litter that is 100% natural material/biodegradable, and any litter tray liners are biodegradable too so that they will break down along with the poo.

(Hamsters & gerbils are naturally omnivores, supplementing their diet with small insects, but most pet hamsters eat a vegetarian diet – commercial gerbil/hamster food is almost always veggie and most people treat them with fruit, veg, seeds and nuts.)

The waste from vegetarian animals like rabbits and most pet hamsters does not pose a significant health risk (unlike cats and dogs) so assuming your hammies are healthy, it can be added to the compost heap.

Hamster & gerbil poop tends to get mixed in with their bedding – bedding that is straw, paper-based or woodshavings can be composted too and is, in fact, a great accompaniment to the poo: they complement each other in the decomposition process.

(Some new commercial bedding products include antibacterial agents – these may be more problematic for your compost heap since bacteria is vital to composting. You may want to dispose of these by other means.)

Droppings from unhealthy animals should not be composted, to avoid potential spread of their illness. For that reason, it is often advised not to compost rabbit droppings from wild animals in case they are ill.