Does hay really wear a rabbit's teeth down? What millimetre-level measurement shows
Published by Planète Pets · managing editor: Clément Lacaille · how our guides are written
"A rabbit's teeth grow continuously, so they must be worn down": the line is everywhere and it reverses the causality. A Zurich team led by Müller and Clauss fed sixteen rabbits four pellets of increasing abrasiveness plus whole hay, two weeks per diet, and published their measurements in 2014 in the Journal of Experimental Zoology (see the study). Our other feeding guides sit in the rabbit food section.
Contents · 4 sections
Growth follows wear, not the reverse
Cheek teeth grew by 1.4 to 3.2 mm a week depending on diet, higher rates than previously reported. Wyss and colleagues refined the measurement in 2016 in the Journal of Veterinary Dentistry using fluorescent markers: 0.93 mm a week for premolars on hay against 2.14 mm on an abrasive diet (see the study). A tooth does not grow at a fixed rate waiting to be filed down: it speeds up when it wears more and slows when it wears less. The balance regulates itself in a healthy rabbit.
What actually wears: phytoliths, not hardness
Abrasion comes from two sources. Internal abrasives are phytoliths, the silica microparticles in grasses and absent from alfalfa; external abrasives are the dust and grit clinging to forage. Martin and colleagues compared pelleted and extruded diets with or without added fine sand in fourteen rabbits, in a 2022 paper in the Journal of Animal Physiology and Animal Nutrition, and conclude that food hardness is a poor predictor of wear (see the study). A practical finding too: rabbits actively avoided the sanded ration in preference tests. And in Müller's work, it was the sand diet that produced the most marked dental abnormalities.
What must not be concluded from this
Nothing here licenses adding an abrasive to the ration: the authors say the opposite. Nothing licenses cutting hay either, whose digestive justification stands intact and rests on other work. These trials are short — two weeks per diet — cover thirteen to sixteen laboratory rabbits in cages, and measure heights and growth rates, not malocclusion diagnoses or clinical follow-up. What they shift is the argument: hay is given for gut transit and chewing time, not to "file" teeth that adjust their own growth. Our article on rabbit teeth, muesli and pellets covers the other side of the problem, selective feeding, and choosing hay also turns on factors other than abrasiveness.
- 0.93 mm/week on hay against 2.14 mm on an abrasive diet, for premolars.
- 1.4 to 3.2 mm/week: the range of cheek tooth growth across diets.
- Most marked dental abnormalities on the sand-containing diet.
- Two weeks per diet, 13 to 16 rabbits: short trials, on laboratory animals.
The right question is therefore not "is my rabbit wearing its teeth down enough?" but "is it eating enough long fibre, for long enough, every day?" — the first regulates itself, the second depends entirely on you.
Frequently asked questions
If growth adapts to wear, is unlimited hay still necessary?
Yes, but for other reasons: gut transit and chewing time. The filing argument is the wrong one, the fibre argument is the right one.
Does a gnawing stick or mineral block wear the molars?
Those objects mostly work the incisors. Cheek tooth wear depends on chewed forage and the phytoliths it contains, not on an object gnawed now and then.
Do extruded pellets wear teeth less than standard pellets?
The 2022 comparison shows food hardness predicts wear poorly: abrasive content, not the manufacturing process, is what weighs in.
See it in the Planète Pets shop: Wooden hay rack with tray for rabbit, guinea pig and chinchilla (€21.90) · the whole shop
This guide is part of Planète Pets’s Rabbits universe. Our advice is general in nature: for any health concern, your veterinarian remains the only reference.
