A rabbit's diet should be built on hay — not as a side dish or a top-up, but as the main event. Every rescue centre and rabbit-savvy vet repeats the same message because it is true: unlimited fresh hay, available every hour of every day, is the single most important thing you can offer your rabbit. Get hay right and you have gone a long way towards preventing the two problems we see most often in rescue rabbits — dental disease and gut stasis.

Why hay sits at the heart of the diet

Around 80 to 90 per cent of an adult rabbit's daily intake should be hay or dried grass. Pellets and leafy greens matter, but they are supporting acts. A rabbit that fills up on pellets and then picks at hay is a rabbit heading for trouble, however good those pellets are.

The reason is simple. Rabbits are grazers, designed to eat little and often throughout the day and night. Their whole digestive system is built around a steady trickle of fibrous food, and hay provides that fibre in exactly the form they can use. It is not a filler to stop them feeling hungry — it is the fuel that keeps their body working properly.

Keeping the gut moving

Rabbits are hindgut fermenters. Food passes through the stomach and small intestine before reaching the caecum, a large pouch where bacteria break down fibre. Long strands of hay are essential here. They keep the contents of the gut moving in the right direction and feed the beneficial bacteria that live there.

Without enough long-strand fibre, gut movement slows, the bacterial balance in the caecum shifts, and a rabbit can develop gut stasis — a painful and potentially fatal condition in which the gut simply stops working. Once a rabbit stops eating, the problem snowballs quickly, because an empty gut is an unhappy gut.

Warning signs to take seriously include:

• Droppings that are smaller, fewer, or misshapen
• Refusing food, or turning up their nose at hay in particular
• Sitting hunched, grinding their teeth, or pressing the belly to the floor
• No droppings at all for several hours

These are emergencies. Ring your vet straight away rather than waiting to see whether things improve on their own.

Wearing down teeth naturally

A rabbit's teeth grow continuously, roughly two to three millimetres a week. That growth never stops, so it has to be worn down. The side-to-side grinding motion of chewing hay wears the cheek teeth evenly and keeps the incisors in check. Soft food and pellets simply do not require that action.

When a rabbit does not eat enough hay, the cheek teeth develop sharp spurs that cut into the tongue and cheeks. Watch for drooling, a wet chin, dropping food while eating, weepy eyes, weight loss or a reluctance to eat hard food. Dental problems are painful and often go unnoticed until a rabbit is already struggling, which is another reason hay should never be rationed.

Hay as enrichment, not just food

Hay is also the cheapest enrichment you will ever buy. Foraging is a natural behaviour, and a rabbit with hay to rummage through has something meaningful to do with their time. A bored rabbit will chew cage bars, dig at flooring, or pull at their own fur instead.

You can make hay work harder by:

• Packing it into a cardboard tube or a paper bag so it has to be dug out
• Scattering a handful across a clean floor area for grazing
• Using a hay rack at nose height so hay stays clean and off the floor
• Storing hay in a lidded box and letting your rabbit forage through the box itself, under supervision

Rotate the ideas rather than using the same one every day. Novelty keeps a rabbit interested, and an interested rabbit eats more hay.

Choosing and storing hay

Quality matters more than brand. Good hay smells sweet and grassy, looks green rather than brown, and is not excessively dusty. Musty, damp or mouldy hay should never be offered — it can cause serious respiratory and digestive illness.

Meadow hay makes a good everyday choice, while timothy, orchard grass, oat and ryegrass hays can all be offered for variety. Oat and other cereal hays are slightly sweeter and are useful for tempting a fussy eater. Mix two or three types in the same rack if you can.

Buy in manageable batches and store hay in a cool, dry spot in a breathable bag or a plain cardboard box. Sealed plastic traps moisture and encourages mould, so avoid it. Topping up a small amount every day keeps the rack appealing and lets you check what your rabbit is actually eating.

Getting enough hay into a fussy rabbit

Offer hay in unlimited quantities, refreshed at least twice a day, and remove any that has been trampled, soiled or rained on. If your rabbit is not keen, cut back on pellets to roughly an eggcupful a day for an average adult, and hide that small portion in the hay so every pellet has to be found among the strands.

Change gradually if a rabbit has never had much hay before — sudden swaps can upset sensitive guts. Mix the new hay with the old for a week or two and let them adjust. With a little patience, most rabbits come round, and the difference in their condition, teeth and general contentment is usually plain to see within a month.