How Much Hay Do Rabbits, Guinea Pigs and Chinchillas Need?

By Dr Duncan Houston

A full pellet bowl can make a small pet look well fed while the hay beside it stays untouched. For rabbits, guinea pigs and chinchillas, that matters: eating hay supports digestion, provides sustained chewing and gives them something natural to do.

The useful question is how much your animal actually eats, not simply whether hay is present. This article explains how to choose and offer it, and when avoiding hay needs a veterinary check.

Quick Answer

Rabbits, guinea pigs and chinchillas need constant access to good-quality grass hay as a major part of their diet. Its fibre supports digestive function, chewing helps wear their continuously growing teeth, and searching through it encourages natural foraging. Hay complements a species-appropriate feeding plan; it does not replace guinea pigs' need for dietary vitamin C or prevent every dental problem. If eating or droppings decrease, contact a vet promptly rather than trying to solve the problem by changing hay alone.

How does hay support digestion?

These animals depend on a fibre-rich diet and the microorganisms in their digestive tract. Hay provides fibre that supports normal gut function. Filling up on concentrated foods can displace that essential intake.

In rabbits, inadequate fibre is one contributor to gastrointestinal stasis, where gut movement slows and food stops moving normally. Pain, stress and other illness can also trigger it. Hay helps reduce dietary risk, but adding hay cannot treat an animal that has stopped eating. See Kansas State University's explanation of rabbit gut stasis.

Guinea pigs and chinchillas also need close monitoring of food intake and droppings. A smaller pile of droppings may mean less food is going in, a digestive problem, or both. It is not enough to assume they are simply constipated.

Why is chewing hay important for teeth?

In rabbits, guinea pigs and chinchillas, the front and cheek teeth continue growing. Eating fibrous forage encourages the repeated grinding needed for normal wear. A chew toy cannot provide the same feeding pattern or replace hay.

However, tooth alignment, injury and established dental disease also matter. A pet can have painful cheek teeth even when the front teeth look reasonable. Drooling, dropping food, choosing easier foods and losing weight warrant examination, especially when hay intake falls. Tai Wai Exotic's guinea pig dental guidance explains why hay avoidance can be a pain signal.

Chinchillas can continue eating despite significant dental disease. Their vet may need a detailed mouth examination under anaesthesia and dental imaging to assess problems that are hidden during an awake examination. Hay remains important, but cannot reverse advanced tooth disease. See the MSD Veterinary Manual's chinchilla dental and digestive guidance.

Do all three species need the same diet?

Rabbits: hay and suitable grass should form the bulk of the diet, alongside appropriate leafy greens and a small measured pellet portion. Avoid suddenly changing the whole menu. The RSPCA's rabbit feeding guidance recommends keeping hay or grass available continuously.
Guinea pigs: offer unlimited grass hay, guinea pig pellets and suitable fresh vegetables. They cannot make their own vitamin C, so hay alone is not a complete diet. Their vitamin C intake needs to come from appropriate food or a supplement advised by their vet. See VCA's guinea pig feeding advice.
Chinchillas: base feeding on grass hay with a measured portion of chinchilla pellets. Do not copy a rabbit's vegetable menu into their enclosure. Keep extras limited and ask a chinchilla-experienced vet about suitable choices. PDSA's chinchilla diet advice also warns that excess pellets can reduce hay eating.

Growing, pregnant, nursing, underweight or chronically ill animals may need a different balance. Get an individual feeding plan before restricting food or changing to a richer hay. The advice here applies to these three herbivorous species, not automatically to every animal sold as a small pet.

Which hay should you choose?

Good-quality timothy, orchard grass or meadow hay can provide an appropriate grass-hay base. A different texture may encourage interest, but there is no need to rotate varieties on a fixed schedule. Introduce a new option alongside familiar hay and watch actual intake.

Alfalfa, also called lucerne, is a legume hay with more protein and calcium than typical grass hays. It is not the default main hay for a healthy adult. Growing animals or those with additional nutritional needs may have a reason to receive it, with species-specific advice. Singapore's Animal and Veterinary Service rabbit guidance distinguishes adult grass-hay diets from the needs of younger rabbits.

Choose hay that smells fresh and is dry, clean and low in dust. Reject mouldy, musty or damp hay. Keep stored hay dry and well ventilated, and remove soiled portions from the enclosure. The MSD Veterinary Manual's hay storage advice supports offering fresh hay daily.

How does hay provide mental enrichment?

Hay takes time to investigate, select and chew. This gives feeding a role beyond filling the stomach. Foraging is a useful way to encourage natural behaviour, but hay alone does not meet every welfare need.

Offer more than one hay area so companions can feed without crowding.
For rabbits, try a clean hay area near their litter tray or an easy-to-reach feeder.
For guinea pigs, offer clean hay piles to explore and hide in, while keeping fresh feeding hay available.
Hide a few pellets from the normal daily allowance among hay, rather than adding extra treats.
Keep some hay freely accessible even when offering a foraging activity.

Supervise new arrangements and check that feeders cannot trap a head or limb. Add variety gradually while keeping familiar resting areas and routines. The RSPCA's rabbit dietary enrichment ideas and guinea pig housing guidance explain how feeding, hiding and exercise opportunities work together.

When does avoiding hay need a vet?

What you notice	What it could mean	What to do
Rejects one new batch but eats familiar hay normally, with usual droppings and activity	A difference in hay quality, smell or texture	Offer fresh familiar hay now, inspect the rejected batch and keep checking intake.
Eats little hay, prefers easier foods, drools or drops food	Dental pain or another feeding problem	Call a vet today for assessment. Escalate immediately if total intake or droppings decrease.
Eating less overall, fewer or smaller droppings, or unusual quietness	Illness, pain or slowing gut function	Call a vet now for urgent advice. Do not wait overnight to see whether a new hay helps.
Stops eating, stops passing droppings, has a swollen painful abdomen, collapses or struggles to breathe	A potentially serious emergency	Contact an emergency veterinary clinic immediately and arrange assessment.

Appetite changes can follow excess pellets, inaccessible hay, stress or dental disease. Other causes include pain elsewhere, infection and, particularly in a suddenly unwell rabbit, an intestinal obstruction. The signs overlap, so owners cannot reliably diagnose stasis at home. VCA's rabbit stasis guidance describes the need to identify an underlying cause, while PDSA's guinea pig health advice highlights the seriousness of reduced eating and digestive changes.

What should you do in an emergency?

A rabbit, guinea pig or chinchilla that has stopped eating needs urgent veterinary assessment. Call ahead and describe when they last ate normally, whether droppings are passing and any pain or swelling. Keep handling calm while arranging transport.

Do not start syringe feeding, give gut-movement medicine or use human painkillers without veterinary instructions. An obstruction or difficulty swallowing can change what is safe. The Rabbit Welfare Association & Fund's syringe-feeding guide stresses getting veterinary advice first to exclude a blockage. Offer familiar hay and water for voluntary intake while following the clinic's advice; do not let attempts at home feeding delay care.

A practical daily hay plan

Check the supply: keep edible hay available day and night, replacing wet or dirty material and replenishing before it runs out.
Watch each animal eat: a shared hay pile can hide one companion's poor intake. Notice chewing, dropped food and whether each animal reaches the feeder comfortably.
Check water and droppings: make sure water is available and bottles work. Compare droppings with that individual's normal pattern.
Review the whole diet: measure pellets and keep a brief food record if hay intake is poor. Discuss adjustments with the vet instead of abruptly withholding familiar food.
Support movement and confidence: provide suitable exercise space, hiding places, compatible companionship and predictable routines. Introduce new foraging activities gently.

If a healthy animal's feeding routine needs improvement, gradual changes and better access can help. If eating has changed because of pain or illness, the outcome depends on identifying and treating that cause.

Common mistakes to avoid

Assuming a full hay rack proves every animal is eating enough.
Continually topping up pellets so hay becomes the least attractive option.
Calling a sudden preference for soft food fussiness without checking for dental pain.
Trying to make an animal eat hay by taking away all other familiar food.
Using hay changes, treats or home remedies to delay care when appetite or droppings fall.

Frequently asked questions

Can pellets replace hay?

For a healthy rabbit, guinea pig or chinchilla, pellets complement a forage-based diet. They should not routinely replace hay. An animal unable to chew needs a veterinary feeding plan.

Can my pet eat only hay?

Do not assume hay alone supplies everything needed. The rest of the diet must suit the species and life stage. Guinea pigs especially need a reliable source of vitamin C.

Is softer hay better for a pet with dental problems?

A softer grass hay may be easier for some animals to manage, but it does not fix painful teeth. Ask the treating vet how to maintain intake while the dental problem is addressed.

Can rabbits and guinea pigs eat fresh grass?

Yes, suitable clean grass can be part of their diet. Introduce it gradually, avoid chemically treated or contaminated areas and never offer lawnmower clippings. See the RSPCA's guinea pig grass and hay guidance.

Make hay eating part of the health check

Fresh hay supports teeth, digestion and natural behaviour, but the benefit depends on eating it. Build a routine that makes hay easy to reach and appealing, and take a drop in appetite or droppings seriously. Early assessment gives your vet the best chance to address the cause before the animal becomes more unwell.

For more owner-focused animal care information, visit ASK A VET™. If your rabbit, guinea pig or chinchilla is eating less or seems unwell, contact a veterinary clinic directly for advice and examination.