A large pen widens a rabbit's bones but does not make them stronger
Published by Planète Pets · managing editor: Clément Lacaille · how our guides are written
Skeletal strength is often invoked to justify a large pen. The intention is good, the argument is wrong — and a far more decisive factor was measured in the very same work. Our habitat guidance is gathered in the rabbit bedding and habitat section.
Contents · 5 sections
A wider bone, not a stronger one
Buijs, Van Poucke, Van Dongen, Lens and Tuyttens compared, in 2012 in the Journal of Animal Science, groups of eight rabbits housed in cages of 0.40 to 1.60 m² — the number of animals staying constant, so what varied was density, from 0.05 to 0.20 m² per rabbit (see the study).
- The tibiofibula diameter increases with floor area (P = 0.008), and fluctuating asymmetry — an indicator of developmental stress — decreases (P = 0.010).
- But bone length and strength do not change (P > 0.1).
- The authors draw the conclusion that matters themselves: the absence of any change in bone strength makes a drop in fracture incidence unlikely.
- Cage enrichment, for its part, changed nothing in fluctuating asymmetry — contrary to what the authors expected.
The factor that really weighs: the floor surface
Buijs, Hermans, Maertens, Van Caelenberg and Tuyttens published in 2014, in Animal, a comparison of housing systems for does (see the study). Tibial cortex thickness there separates individual housing (1.38 mm) from semi-group housing (1.45 and 1.46 mm depending on floor, P = 0.045): the gap therefore lies between housing systems, not between floor types. The authors decline to read it as a benefit, writing that the extra activity may come from locomotion or from fleeing aggressive pen mates.
The clearest result of that study lies elsewhere, and it is striking: 65% and 68% plantar hyperkeratosis on wire flooring, against 5% on solid plastic slats (P < 0.0001) — and that despite a 1,000 cm² plastic footrest fitted on the wire floors. Space changes nothing in that figure; the floor surface changes everything.
What these studies do not show
These are farmed rabbits: growing fattening animals in the 2012 study, breeding does of a single strain in 2014. Neither follows an adult pet rabbit, neither compares "cage" with "supervised free range in a flat", and even the largest cage tested offered only 0.20 m² per animal. The cortex gap, 0.07 to 0.08 mm, has no known clinical meaning — the authors call for further work. Above all: none of these publications measures an actual fracture rate, whether during handling or after a fall.
What to take away
- Keep providing space, but for the right reasons: activity, behaviour, foot health — see our guide to minimum pen area.
- Remove any wire flooring. It is the most quantified and most directly transferable action in this file, and the footrest was not enough to compensate: see wire or solid flooring.
- Fracture prevention remains a matter of handling, not square metres: it is all in our article on how to hold and carry a rabbit safely.
Frequently asked questions
Does a free-range rabbit have better bones?
Nobody has measured it. The available work compares cages with each other, never a cage with free housing.
Is a fabric mat enough on a wire floor?
A rigid 1,000 cm² footrest was not enough in the 2014 study. A solid floor across the whole area is better.
Should rabbits be group-housed for their bones?
The authors themselves do not rule out that the extra activity comes from conflict between animals. That is not a sufficient argument. Find all our guides on the rabbit hub.
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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.
