Short answer: Rabbit and guinea pig teeth are open-rooted: they grow continuously, throughout life, and stay the right length only because chewing wears them down. Hay, or grass, does most of that work and should make up at least 80% of what a rabbit eats. When the balance fails, teeth can overgrow, form sharp spurs or stop meeting properly, which needs a rabbit-savvy vet. Never use dog or cat dental products on rabbits or guinea pigs.
Teeth that grow for life
A dog's or cat's teeth stop growing once they are fully formed. A rabbit's never do. Rabbits and guinea pigs have open-rooted teeth (vets call them elodont): the incisors at the front and the cheek teeth at the back keep growing, continuously, throughout life. Chinchillas and degus are the same.
That growth is normal and healthy, as long as it is matched by wear. Fibrous food is ground between the upper and lower cheek teeth with a side-to-side chewing action, and the front teeth wear against each other as they crop. While growth and wear stay in balance, the teeth keep the right length and shape.
Rabbits also have a second, tiny pair of upper incisors, the "peg teeth", tucked just behind the front pair. If you spot them, that is normal.
Hay does the work
What keeps the balance is diet, above all hay. Long strands of grass hay take a great deal of chewing, and that grinding is what wears the cheek teeth evenly. Hay, or fresh grass, should make up at least 80% of a rabbit's diet, with clean hay available all day, every day.
The rest is a supporting cast: a variety of fresh leafy greens and a small, measured portion of pellets. Pellets and cereal-based mixes are eaten quickly, with far less chewing, so a diet that leans on them wears the teeth less. Gnawing blocks help the front teeth a little, but they cannot do for the cheek teeth what hay does.
Guinea pigs need the same hay-first diet. They also need vitamin C every day from their food, because they cannot make their own; ask your vet how best to provide it. Make any change to a rabbit's or guinea pig's diet gradually.
What vets look for
When wear and growth fall out of balance, a rabbit-savvy vet looks for:
- Overgrowth. Front teeth that are too long, curve or grow past each other, sometimes into the lips or gums.
- Spurs. Sharp points on the edges of the cheek teeth that can cut into the tongue or cheeks.
- Malocclusion. Teeth that no longer meet properly, so they cannot wear each other down. Some rabbits are born with jaws that do not line up; in others it develops over time.
- Root changes. Roots that grow deeper into the jaw, which can show as a runny eye or a swelling along the jaw.
The cheek teeth sit far back in a long, narrow mouth. A vet can see some of them in an awake rabbit with an instrument, but a full examination often needs sedation or an anaesthetic, and X-rays.
At home the signs tend to be indirect: eating less or picking only soft foods, dropping food, a wet chin or drooling, weight loss, smaller or fewer droppings, a runny eye, a swelling along the jaw, loud tooth grinding, or a dirty bottom from being unable to groom.
Why dog and cat dental products are not for rabbits
Petdentist® makes oral-care products for dogs and cats. None of them should be used on rabbits, guinea pigs or other small mammals, for three reasons.
- The problem is different. In dogs and cats, home care is about plaque at the gumline. In rabbits and guinea pigs it is about the length, shape and wear of teeth that never stop growing. Toothpaste, brushing and plaque-focused products are not part of rabbit care.
- The gut is different. Rabbits and guinea pigs are herbivores whose digestion depends on a constant flow of fibre and a delicate balance of gut bacteria. Rabbits cannot vomit, so whatever goes into the mouth goes all the way through. Powders, probiotics, pastes and water additives made for dogs and cats have not been assessed for them, and anything that changes the taste of water can put a small herbivore off drinking.
- Evidence does not transfer. We never apply dog evidence to cats, and we certainly do not apply it to rabbits. A product designed and tested for one species says nothing about its safety in another.
Petdentist® sells no products for rabbits or guinea pigs, and this article is education only. If something is not labelled for rabbits, do not give it to a rabbit, and ask your vet before adding anything to the diet or water.
How to check your rabbit's front teeth safely
You cannot see the cheek teeth at home, but you can keep an eye on the front ones. Once a week:
- Stay low and calm. Sit on the floor with your rabbit on a non-slip mat or on your lap. If you need to lift them, support the chest and the hindquarters, and never lift by the ears or the scruff.
- Stroke first. Let your rabbit settle with a gentle stroke along the face and cheeks.
- Part the lips gently. With a thumb, lift the upper lip at the front, just enough to see the incisors. Do not try to open the mouth.
- Look. The upper front teeth should sit just in front of the lower ones, with even, smooth edges, neither too long nor curving, and no chips, blood or swelling.
- Check around the mouth. Feel along the jaw for lumps, look for a wet chin or a runny eye, and note whether droppings are their usual size and number.
- Weigh regularly. Weight loss is often an early sign, and kitchen scales work for most rabbits and guinea pigs.
Stop if your rabbit struggles: rabbits can injure their backs by kicking out when they feel insecure. Never try to clip or file teeth at home. Clipping can split or crack teeth and leave sharp edges, and trimming is a job for your vet.
When to see a rabbit-savvy vet
In veterinary terms, rabbits and guinea pigs are "exotic" species, and dental work in them needs particular experience and equipment. When you choose a practice, ask whether a vet there has a special interest in rabbits or small mammals.
- The same day: a rabbit or guinea pig that stops eating, or stops passing droppings. Do not wait overnight.
- Promptly: overgrown or broken front teeth, drooling or a wet chin, dropping food, eating less, weight loss, a runny eye, or a swelling on the face or jaw.
- Routinely: a dental check at least once a year, or as often as your vet advises. Rabbits that have had dental problems often need checks more frequently.
When to see your vet
If you notice loose or wobbly teeth, swelling, discharge, bleeding that does not settle, reluctance to eat, dropping food, drooling, pawing at the mouth or any change in behaviour, please contact your veterinary surgeon promptly. Home care supports professional care — it never replaces it.