Why is My Rabbit So Fat? Controlling Your Small Animal’s Weight

Laurie Hess, DVM, DABVP
By Laurie Hess, DVM, DABVP on Aug. 30, 2016

By Laurie Hess, DVM, Dipl ABVP (Avian Practice)

Just like people, dogs, and cats, pet rabbits can get fat. We all love to eat, and so do they. Unlike their wild counterparts, however, pet rabbits don’t get the exercise they need to be able to munch away all day. Plus, they don’t have to seek out food the way wild bunnies do, so pet rabbits tend not only to hop less but also to gain more.

Recognizing that a rabbit is fat can be difficult, as female rabbits normally have a fold of skin – the dewlap – under their chins to store fat. In an overweight rabbit, it may be difficult to feel the spine under layers of fat along the back. Fat rabbits may also have extra folds of skin around their genital region, trapping urine and fecal pellets and leading to dermatitis (skin infection or inflammation) and matted fur from the accumulation of moisture and bacteria between skin folds that they are unable to reach back to groom.

Small animals that are overweight can develop many of the same problems that overweight people can, including arthritis and joint problems (which is especially common in guinea pigs), as well as sores or ulcers on the bottom of their feet from carrying around all those extra pounds. Overweight rabbits may also have trouble turning around to reach their hind ends to ingest their first morning stool – the cecotrophs – that contain essential nutrients and that are typically softer than normal fecal pellets. Added weight can also be taxing on a bunny’s heart, as it has to work extra hard to pump blood out to a larger than normal body.

It’s better for pet rabbits to eat right to prevent obesity rather than to try to put them on a weight loss plan once they have become accustomed to eating in a certain way. So, how can you help your rabbit (or other small, herbivorous mammal, such as a guinea pig or chinchilla) stay lean and healthy? Here are five tips to proper weight management in these species:

It’s All About the Hay

The staple of the diet for an adult rabbit, guinea pig or chinchilla should be hay. Hay is important not only to maintain a healthy population of bacteria in their gastrointestinal (GI) tracts to ferment and digest the food they eat, but also to wear down their continuously growing teeth. Wild rabbits chew on rough, fibrous grasses all day to keep their teeth in shape and their GI tracts happy. While we can’t replicate this diet exactly for our small and furry pets, hay provides the fiber pet rabbits need to keep them healthy, too.

Portion the Pellets

Pellets are predominantly carbohydrate, and who doesn’t love to eat carbs? The same is true for pet rabbits and too many carbohydrates can pack on the pounds and upset the pH of the rabbit’s GI tract, throwing off the normal balance of their intestinal bacteria and leading to gas production, discomfort and often, ultimately, to decreased appetite. Rabbits eating large amounts of crumbly pellets rather than fibrous hay also tend not to wear down the surfaces of their teeth properly, resulting in overgrowth and formation of sharp spurs on their continuously growing teeth that eventually cause pain on chewing, decreased appetite, a slow down of food passage through the GI tract and the development of a life-threatening condition commonly seen in rabbits called GI stasis. Typically, rabbits with GI stasis must be treated with GI motility-enhancing drugs, fluids and syringe feeding to recover. If left untreated, rabbits with GI stasis can die.

The rule of thumb for healthy pet rabbits is no more than a quarter of a cup of high fiber pellets per four to five pounds of bunny per day. If your rabbit weighs more than this, than he or she can get a little more, and if he or she is less than four pounds, he or she needs less. Limiting pellets can be hard, as most rabbits chose them over other foods. But in the end, your rabbit will be healthier and feel better if you cut the carbs.

Go for the Greens

Like hay, greens promote chewing and contain fiber. They are also low in calorie, so rabbits can generally munch on greens to their hearts’ content without gaining weight. Greens also have the added benefit of containing water – something herbivores need lots of for proper digestion. Fresh leafy greens keep bunnies and other small mammals hydrated and promote the normal movement of food through their GI tracts. Rabbits also have a tendency to absorb huge amounts of calcium from their food, which can settle out in the bladder like sand and can stick together to form bladder stones requiring surgery to remove. The water in greens helps flush out the bladder and lessens the likelihood of calcium forming this sediment in the bladder.

Two words of caution about greens, however. First, like some people, some rabbits can’t tolerate huge amounts of greens without developing diarrhea. Every rabbit is different in terms of how much water he or she can ingest without having loose stool. Second, while the water content of most greens actually helps keep calcium-based bladder sediment down, some greens – such as parsley, kale, and spinach – actually contain large amounts of calcium and should be fed just a few times per week.

Temper the Treats

We all love treats, especially sugary, fatty ones, as do rabbits. But high-sugar or high-fat treats like fruit (dried or fresh), seeds and nuts can alter the motility of a rabbit’s GI tract, interfere with digestion, and lead to weight gain. These foods are not normally part of a rabbit’s diets, and although they love them, rabbits should generally not be offered them. An occasional piece of high-fiber fruit, such as a pear or apple, is fine as a treat, but other sugary fruits, such as bananas and grapes, or high-fat seeds and nuts, have no place in a rabbit, guinea pig or chinchilla’s feeding plan.

Hop to It

Eating right is the key to weight loss in rabbits, guinea pigs and chinchillas, however, without exercise, it’s hard to maintain a proper weight. Many pet bunnies spend most of their days in small cages with little room or opportunity to exercise. To promote a healthy body weight, small mammals should have several hours of out-of-cage time daily and should be encouraged to move around. Providing your pet with a solid, non-slip surface to move around on and placing food bowls around the room force the rabbit (or other small mammal) to move around to eat and to burn calories on the way. Having small mammals hunt or forage for bits of food hidden under pieces of paper or buried in chewable cardboard boxes is another way to promote exercise while providing mental stimulation, as well.

Lean, well-muscled rabbits will likely live longer and feel better than their overweight counterparts, and following these proper weight-management tips can help your pet be well on its way to healthier living.

Dagmar Hijmans via Shutterstock 

Laurie Hess, DVM, DABVP


Laurie Hess, DVM, DABVP


Originally from New York City, Dr. Laurie Hess is one of approximately 150 board-certified avian (bird) specialists worldwide. After...

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