No Bored Bunnies: Environmental Enrichment for Rabbits in Research

The following email discussion took place on the Laboratory Animal Refinement & Enrichment Forum in February 2016. Submissions by Carey Allen, Evelyn Skoumbourdis, Jacqueline Schwartz, Jennie Lofgren, Jennifer Defosses, Kristina Carter, Leslie Jenkins, Lorraine Bell, Marcie Donnelly, Marloes Hentzen, Michele Cunneen, Reneé Gainer, Sarah Thurston, Stacie Havens, and Tom Ferrell.

What are practical and effective options for enriching the cages of single- or pair-housed rabbits?

Any toy the rabbits can manipulate works well; this includes bird toys that you can attach to the cages. I’ve also found that canning jar lids—with the rubber part discarded—are a big hit. Get the smaller size (70 mm diameter) to avoid having the rabbits push the lid’s band over their noses and get them stuck. Regular access to a play pen, furnished with toys such as tubes or suspended hay baskets, offers great enrichment for caged rabbits. We use “puppy play pen” segments that you can purchase at any pet supply store. They are easy to set up and fit into available space. (Lorraine)

To provide foraging enrichment for our rabbits, I put some veggie bites or fruit gems on the bottom of empty glove or mask boxes and stuff a thick layer of hay over it. Empty paper towel rolls stuffed with hay also keep our rabbits busy foraging for a considerable amount of time. (Carey)

Our rabbits get small hard plastic toys (e.g., barbells) that they chew on and knock around. We also give them suspended rattles for noise-making; they seem to enjoy making a racket with them. They also have huts or little raised platforms under which they take siestas or onto which they hop to get a good lookout. Plastic tubes tightly stuffed with hay provide the rabbits with a very attractive opportunity to forage and also to play: After all the hay has been retrieved, the rabbits push the tunnels around with great vigor creating quite a noise, knocking the hard plastic material on the cage walls over and over again. (Marcie)

I have found that hanging a NutraBlock (purchased from Bio-Serv) by a stainless steel chain at the top of the cages of our rabbits provides effective enrichment. The animals have to stretch up on their hindquarters to reach the block and nibble and gnaw at it. After a few days the block will have been eaten. I leave the empty chains, as the rabbits like to chew on them. Each rabbit gets a new block attached to the chain once every week. I use the NutraBlocks because they are low in sugar and have not interfered with any studies. The rabbits also love to play with the hard plastic barbells. (Stacie)

We put a rat cage turned upside down in each of our rabbit cages so the animals can get on top and, typically, stretch out on them. Each cage is also equipped with a spiral hay feeder and a canning jar lid; the rabbits love throwing these lids around. They also have a sturdy pet toy hanging on the door of the cage. (Renée)

The caged rabbits in my care enjoy a variety of enrichment options: Cardboard boxes to sit on and/or tear apart, autoclaved hay as a daily treat, autoclaved non-sprayed apple tree branches for gnawing, baby rattles and hard plastic key sets for making noise. They also get papaya pills, which they love to eat. The pills entice the rabbits to come up to the front of the cage, thereby making health checks easier, and they prevent the development of fur balls. (Michele)

Each of our rabbits has a block of pine wood for gnawing and access to a daily replenished hay rack that is attached to the front of the cage. (Marloes)

Our rabbits always have one hard plastic toy to toss and a block of wood to chew. I also hang “Bunny Blocks” on a chain in their cages. The blocks are sweet treats with a hard texture, so the rabbits can engage in a lot of gnawing. They receive hay daily in a large paper tube and/or an empty glove box. For holidays and other special occasions, I will add dried apple pieces, shredded wheat, or banana chips to the hay. I have found the ultimate bunny goodie is bite-sized unsweetened shredded wheat. When I visit my rabbits and shake the shredded wheat in the bag, everyone gets excited and comes running to the cage fronts to get a treat. It’s a riot! (Evelyn)

The rabbits I care for go crazy for plain Cheerios! They will run to the front of the cage, all of them banging their toys until you get to them and hand them those treats. (Marcie)

We have fantastic animal care technicians who love their rabbits and do everything in their power to optimize their living conditions: They get a rotation of rattles, little balls, little wood blocks and dumbbells, daily free hay or hay stuffed into empty cardboard glove boxes, paper towel cardboard tubes, or paper bags. The technicians groom the rabbits regularly with brushes; they also offer them special food treats, such as carrots or frozen fruit. (Jennie)

How do caged rabbits react to music as a potential enrichment option?

The rabbits in my care are much calmer when radio music is playing in their rooms. They don’t startle as easily and are less skittish. (Jennifer)

We’ve also noticed a calming effect of low-volume instrumental music, especially on Dutch belted rabbits. (Tom)

It’s my experience that low-volume instrumental music has a positive impact on New Zealand whites; they get noticeably calm and less startled by noise when the music is playing. When I first started trying music as an enrichment option for our rabbits, I would just use my phone to play Pandora classical stations; this worked great until the commercials would come on and the entire room of rabbits would instantaneously freak out! Rabbits probably get scared when they hear unfamiliar human voices. (Sarah)

We have a large room of caged female rabbits at our lab. Earlier this year, noisy construction was going on close to the animals’ room. The rabbits became very restless and engaged in a lot in stomping. Many of them showed the behavioral pathology of fur-pulling/eating, which is an alarming sign of intense distress. The rabbits were used to listening to “top 40” type music at that time. When I noticed the impact of the construction noise on the animals, I switched to soft spa and classical music. The effect was amazing: The rabbits became much more relaxed and less startled, and their behavior became normal again. (Carey)

I am a bit hesitant to give our New Zealand white rabbits hay stuffed in some sort of cardboard or paper bag because they are on cholesterol studies. Is there any safe, digestible cardboard? Has anyone encountered negative effects giving cardboard to their rabbits? (Kristina)

We have been using autoclaved cardboard boxes and paper bags filled with hay for several years with our New Zealand whites and have never had digestive issues. The rabbits shred the paper material; I never saw them eating it. (Sarah)

We give cardboard boxes regularly to our rabbits (NZWs) and have encountered no issues. (Jacqueline)

We’ve had a number of bunnies on cholesterol studies here. I’ve given them empty glove boxes, cardboard tubes, or paper lunch sacks on almost a daily basis. We haven’t had a single digestion problem and there was no indication that access to the paper material affected the rabbits’ cholesterol levels. (Evelyn)

Based on your own experience, would you agree that your presence and friendly interaction with the caged rabbits in your charge provide an effective (entertainment for the animals and for yourself) and useful (stress-buffer during handling procedures) strategy for environmental enrichment?

Definitely yes! Years ago, I was assigned a group of rabbit rooms where the animals hadn’t been given any sort of enrichment—except hay, which I don’t consider to be enrichment but rather a necessity for rabbits. Quite a number of these nearly 150 rabbits were stompers and growlers any time you opened the cage door. Those who weren’t aggressive were very fearful. I got permission to try some enrichment items with them and purchased canning jar lids, which I placed in their cages. Each day, as I went about the normal husbandry duties in the rooms, I would interact with each rabbit, picking up and “tinging” the lid, offering timothy hay by hand, or just speaking to the animal. In a relatively short time I was left with only one rabbit who remained intractable; all the others had become relatively docile and easy to work with. (Lorraine)

I would also say, resoundingly, yes: frequent friendly interaction with rabbits is very useful. We make it a point to visit our rabbits often and gently touch them so that they have no reason to get distressed when we need to manipulate them for experimental procedures. (Leslie)

Yes, to all! If they are used to friendly interaction, rabbits are less afraid of humans, which makes husbandry and research-related procedures less stressful for them and for the person who is handling them. It’s my experience that caged rabbits will actually seek human attention and human contact if they have been given the chance to get well socialized with humans and gain trust in them. (Jacqueline)