Overweight and Underweight Rabbits


Slim and sleek. This is veterinarian and author Dr. Susan Brown’s description of what a healthy rabbit looks like, although lack of exercise, poor diet, and overfeeding can drastically change that appearance.

Increased weight interferes with normal activities and puts a rabbit at higher risk for many health problems. Dr. Brown, an exotic animal veterinarian with a special interest in rabbits for over fourty years, notes some of them: cardiovascular, joint, gastrointestinal, urogenital, and liver diseases. Should there be any reason for surgery, an obese rabbit is at greater risk as well. In addition, an obese rabbit who is unable to hop around loses out on so many things, including the fun of exploring and following that inquisitive nose.

Signs of Obesity

In addition to the visible change in a rabbit’s shape and agility, a caregiver may notice:

  • Soft cecotropes present around the anus and in the cage or litter box area
  • Difficulty grooming, resulting in a dull or stained coat
  • Interference with eating or drinking (large dewlap)
  • Urine scald; inability to posture correctly
  • Folds of skin around anal area, where cecotropes, feces, and urine collect
  • Locomotor problems, resulting in decreased activity levels (sedentary)

Note that the signs listed above are not exclusive to obesity and may indicate some other health problem.

Rabbit Size Infograhic courtest of RSPCA

Diagnosis, Treatment, and Prognosis for Recovery

A qualified veterinarian can determine whether additional health issues (e.g., arthritis, pododermatitis) are a concern. Determining the rabbit’s ideal weight and the length of time necessary to achieve that goal will help to establish a course of action that the caregiver can follow.

Inappropriate diet is the primary cause of weight gain; thus, diet becomes the focus for treatment. As noted in the “Home Care” section below, the best diet comprises grass hay, fed daily in unlimited quantities. Safe weight loss occurs when a rabbit is put on the appropriate diet and is eating large quantities of hay. For additional information, reference “Disorders of the Cecum” as well as diet-related articles on this website.         

Home Care of an Overweight Rabbit

If an obese rabbit is put on an inappropriate diet and loses weight too rapidly, the rabbit can become ill very quickly and be at risk for hepatic lipidosis. In this condition, fat cells replace liver cells, resulting in a severely damaged liver. If a rabbit becomes anorexic (loses his appetite) for any reason, the condition should be considered an emergency and treated before hepatic lipidosis becomes a threat.

Dr. Tomáš Chlebeček, who regularly treats rabbits at his clinic, stresses the importance of an appropriate diet:

To achieve and sustain safe weight loss, it’s important that a rabbit consume a healthful diet. Most important is free access to grass hay. When a variety of grass hays are available, I recommend offering a mix, though caregivers should be aware that alfalfa is often in with orchard grass. I seldom recommend alfalfa for companion rabbits and never for overweight rabbits.

Straw is never a substitute for grass hay, regardless of how obese a rabbit may be. Though fibrous, it is devoid of good nutritional value: it’s too low in both calories and protein, and it lacks valuable trace minerals. Feeding an obese rabbit a diet of straw is potentially dangerous and can lead to fatal hepatic lipidosis. Even if the diet were supplemented with some pellets and leafy greens, the rabbit would likely suffer muscle problems and weakness. The rabbit would suffer in other ways too – he would not be a happy, content bunny.

When a rabbit is obese, food pellets are usually part of the reason and their reduction must be accomplished slowly, especially if the rabbit is not eating the proper amount of grass hay on a daily basis. If the pellets are alfalfa-based, I recommend a gradual change to a timothy-grass-based food. Mixing the two foods allows for gradual introduction of the new pellet.

Free-feeding of pellets must be discontinued for the health of the rabbit. I suggest that caregivers divide a measured amount of pellets into two feedings (e.g., morning, evening), which often has the added benefit of encouraging the rabbit to browse hay between feedings. If a pellet mix contains morsels such as dried legumes or corn, grains of any kind, or high-carbohydrate foods, those items should be discarded.

Fatty foods (e.g., seeds) and high-starch/high-sugar foods can lead to serious problems and should not be fed, even as treats.

Dr. Brown comments further:

Although leafy green vegetables can be a part of a healthy rabbit’s diet, feeding them in excess can cause a rabbit to lose weight too quickly and be unable to maintain proper weight over time. This is because fresh foods are less calorie-dense than hay due to the high water content. In addition, feeding too many greens will fill up a rabbit, making him less likely to eat hay, the most important part of the diet. It is preferred to discontinue leafy greens during a serious weight-loss program.

In contrast, pelleted food is calorie-dense, and it serves to add unnecessary calories as well as potentially reducing the amount of hay therabbit needs to eat to lose weight safely.

The most rapid way to accomplish healthy weight loss is to feed a diet of quality grass hay only. There are, however, two very important considerations with this: the rabbit must be freely grazing hay throughout the day, and the hay must be of good quality. If either of those conditions is not met, then a rabbit must be fed pellets to ensure proper nutrition and prevention of hepatic lipidosis; this has already been addressed.

Quality hay is not always available locally or throughout the year, and quality can vary for various reasons, such as climate, soil, and the way the hay is handled and stored. One very general guideline is to feed the same hay as is fed to horses, not the pasture grass that is fed to ruminants (e.g., cattle, sheep). When there is difficulty locating a good source for quality hay, the local or regional rabbit rescue group can often provide assistance.

If your rabbit refuses grass hay, don’t become discouraged. One way to entice a hesitant rabbit is by offering the hay as part of a homemade cardboard toy. For example, stuff an empty plastic-wrap tube with hay. Eventually most bunnies will begin eating hay in the proper amounts. This can sometimes be more easily accomplished when the overweight rabbit is in the company of other rabbits. It may be necessary, however, to separate the overweight rabbit from his bunny pal(s) during feeding time, especially when the other rabbit is fed pellets. Entice the overweight rabbit to a different area by offering just a few little pieces of greens, keeping Dr. Brown’s comments above in mind. Even after weight loss is accomplished and the rabbit is on a maintenance diet, the bunnies may have to be separated during feeding time to ensure that the once-overweight rabbit does not overeat. Separating the rabbits also allows each to eat at his or her own pace.

In addition, after weight loss the rabbit’s maintenance diet can also include more leafy green vegetables. However, measuring the amount of vitamin-rich greens remains important, and they should be restricted if they make the rabbit less likely to eat hay. It is also recommended that caregivers base the pellet amount on the individual needs of a rabbit (e.g., health, age, weight, activity level); the amount fed one rabbit may not be appropriate for another. Supervising the kind and amount of treats is another consideration. Perhaps include some non-food “treats” in order to keep the emphasis on grass hay, the single most important part of the diet. Reference the various diet-related articles on this website for further discussion.

Monitoring the rabbit’s environment – for example, protecting against high temperatures that can quickly lead to heat stroke – will help prevent other health problems. Giving an overweight rabbit plenty of opportunity for exercise and playtime is important. If the rabbit has a buddy (of any species), social time will become more enjoyable when the overweight rabbit is able to move more easily.

When a rabbit is obese, gentle touch can help comfort and also reduce stress. In the article “Deepening the Bond: How to Connect with Your Rabbit through Massage,” licensed massage therapist Chandra Beal advises that “laying on of hands or light fur strokes would be appropriate for showing affection and reducing stress while the bunny is dieting.” Tellington TTouch® is another form of bodywork that can benefit your rabbit. Providing extra attention will help turn the rabbit’s focus from food to more enjoyable forms of interaction.


There are many reasons a rabbit may be underweight. Some rabbits suffer from malnourishment early in their life; parasites can result in weight loss. But the primary reasons are the ones discussed by Dr. Susan Brown:

The most common reason for weight loss is decreased appetite and, thus, a reduced intake of calories. This is generally due to disease, including dental, gastrointestinal, cardiovascular, musculoskeletal (arthritis of joints or the spine), metabolic (liver, pancreas, or kidney), and cancer. Most of these involve either pain that will make it difficult for the rabbit to eat or a build up of toxins in the body that affect the brain and other organs, making the rabbit feel either nauseated or not hungry. Infectious disease, particularly upper respiratory, may make it difficult for a rabbit to smell food and thus will reduce appetite.

In addition, a diet that is primarily composed of fresh vegetable greens instead of grass hay can be very dangerous because the greens have fewer calories, due to high water content. This will lead to unhealthy weight loss. Rabbits should always be fed a diet that is primarily grass hay, offered in unlimited amounts. Inadequate availability of fresh water may reduce food intake as well.

There are other considerations. If the rabbit becomes anxious because of activity near the feeding area, such as a barking dog, active children, or other loud noises, the rabbit may not want to eat. When there is more than one rabbit, a dominant one may guard the food and prevent other rabbits from having access to it. This is one reason that I recommend that grass hay be available in several widely spaced locations.

Elderly rabbits sometimes present challenges, as reduced activity – perhaps due to painful arthritis – causes them to lose muscle mass. Building muscle mass becomes the goal and, in the case of an arthritic bunny, non-steroidal anti-inflammatory drugs (NSAIDs), physical therapy, and alternative pain management (e.g., acupuncture) can help. Dietary considerations are addressed in the “Home Care” section below.

Signs of Underweight in Rabbits

Depending upon the reason for the weight loss, a caregiver may notice:

  • Emaciated appearance (e.g., prominent backbone, pelvis, and ribs)
  • Abdomen “caved in” rather than smooth at the area bordered by the last rib, the thigh, and the spine (sort of a triangle)
  • Dull, rough coat
  • Lethargy
  • Fewer fecal pellets, perhaps smaller, drier, and misshapen
  • Unusual activity level, signaling a search for water or for food (due to inappropriate diet)
  • Pain (e.g., hunched appearance, inability to stretch out; reluctance to move; grinding or chattering of teeth; partially closed eyes)
  • Dropping of uneaten food

Being alert to potential weight loss can help prevent serious problems. If a rabbit refuses food for an extended period of time, such as twenty-four hours, caregivers should be concerned because rabbits cannot fast, not even when ill or injured. A sudden cessation of eating or a decreased amount of feces signals a problem as well. Continued inappetence can quickly result in a life-threatening condition. Without intervention, gastrointestinal hypomotility (slowdown of transit times in the digestive system) can lead to GI stasis (shutdown). Hepatic lipidosis also becomes a threat.

Diagnosis, Treatment, and Prognosis for Recovery

Dr. Jason Hutcheson, whose practice is devoted solely to rabbits and other exotic animals, indicates various steps in making a diagnosis:

If the cause cannot be determined by a physical exam, we proceed to a full work-up, which includes a complete blood count, serum chemistries, urinalysis, and radiographs. These diagnostics often pinpoint diseases such as renal failure (kidney disease), dental disease, liver disease, certain cancers, or chronic infection.

Sometimes lifestyle, not disease, is the causative factor in weight loss. Poor diet can result in weight loss as well as weight gain, and so I always discuss the importance of the appropriate diet. Factors such as age, agility, and exercise options are also part of my discussion with the rabbit’s caregiver.

In addition, it’s helpful to hear about the rabbit’s life, including house location and other animal companions or children the rabbit lives with. For example, it may be that the rabbit’s area is too warm, another pet appears threatening, the rabbit is in a high-traffic area or, conversely, isolated away from the family, or perhaps children inadvertently mishandle the rabbit. Such stressors may inhibit a rabbit from eating and drinking as he should.

Dr. Tomáš Chlebeček discusses the impact of pain on weight loss:

If the rabbit is exhibiting pain, the cause must be determined and addressed or the rabbit will rapidly decline. Blood work can often help pinpoint the problem. A common cause of pain, especially in rabbits who don’t eat enough hay, are molar points (spurs). These razor-sharp lateral projections are caused by abnormal molar wear. They cut the tongue and cheek, creating a painful condition that prevents the rabbit from eating. A less obvious source of pain can be caused by elongated tooth roots, with or without abscesses, also caused by lack of eating hay; this can only be diagnosed with a lateral-lateral skull X-ray. Of course, other dental disorders cause hyporexia [diminished appetite], such as maloccluded incisors.

Rabbits do not have much of an energy reserve. It is critical to syringe-feed anorexic rabbits until they can eat on their own. Because it’s specially formulated for ailing rabbits, I recommend Critical Care™ but a mashed pellet slurry can also be fed.

There are some additional considerations, as noted by Dr. Brown:

Since pain is a common cause of weight loss, pain management is often one of the treatments. In cases such as arthritis of the joints or spine, the treatment may be for the lifetime of the rabbit. In cases such as infectious or metabolic disease, the appetite may return after the condition is addressed. There are many factors to consider when treating a rabbit for weight loss. It’s important to realize that treatment is not simply a matter of increasing caloric intake.

Note: Rabbits’ teeth have an apex instead of a true “root,” but the word “root” is used in this article.

Home Care of an Underweight Rabbit

If a rabbit is ill or injured, a home-care plan will be prescribed by the veterinarian. Eliminating stress to the extent possible is important for every bunny and especially for the underweight rabbit. A proper diet and other considerations are also important, as Dr. Chlebečekexplains:

It’s not necessarily a good idea to increase the amount of processed pellets in an underweight rabbit’s diet. Determining the cause for underweight guides my recommendations for diet.

In many cases, an underweight rabbit will benefit from increased consumption of fiber-laden foods, especially grass hay and, to a much lesser extent, leafy greens. (However, too many greens can lead to weight loss instead of weight gain.) A high-fiber diet reduces dental and other health problems. In addition to any underlying health issues, it’s important to look at all the factors that might be contributing to the rabbit’s eating behavior. For example, if an underweight bunny eats slowly, it may be necessary to give him uninterrupted feeding time away from the company of other animals and children.

Sometimes an ill or elderly rabbit may require special dietary attention, perhaps needing a measured amount of quality pellets or homemade ground-pellet mush, but the rabbit should also be encouraged to eat grass hay.

Although it’s logical to assume that a less-active rabbit will gain weight, the opposite is sometimes the case. Weight loss can result from a reduction in muscle mass, often due to inadequate exercise caused by decreased mobility, lethargy, pain when moving, or because the rabbit is caged too much of the time. Extended time outside of the cage is important. Placing hay bins and litter boxes in several locations may also stimulate more activity. Rabbits will often have greater ease of movement if a rug or other heavy material is placed on smooth floors (e.g., wood or tile). When a rabbit has a buddy, one of them often leads the other on excursions, facilitating increased exercise.

When there are two or more rabbits, caregivers should also be mindful of social issues. Observing actions surrounding the food – such as one rabbit guarding the food area or thwarting the others’ attempts to get at food or water – will enable the caregiver to make necessary changes for the benefit of all the rabbits. For example, grass hay can be made available in several locations, spaced apart.


Several articles posted on this website were referred to in this two-part article or may otherwise be of interest:

Caregivers may want to consider supplementing their rabbit’s care with alternative therapies, some of which are addressed in separate articles posted on this website. There are times when combining the expertise of both standard and alternative treatments offers the best supportive care. When researching complementary treatments, be aware of training and qualification requirements and give careful consideration to the health, nature, and needs of your rabbit. Be clear and realistic about your expectations and goals for treatment, which should prioritize your rabbit’s comfort and quality of life.


My sincere thanks to the veterinarians named in this article for sharing their expertise during personal interviews and in subsequent feedback. In addition to House Rabbit Handbook: How to Live with an Urban Rabbit, the following list of publications, although by no means comprehensive, may assist those who desire additional research.

  • BSAVA Manual of Rabbit Medicine and Surgery. Anna Meredith and Paul Flecknell (Eds.)
  • Clinical Radiology of Exotic Companion Mammals. Vittorio Capello and Angela Lennox
  • Color Atlas of Small Animal Anatomy: The Essentials. Thomas O. McCracken and Robert A. Kainer with David Carlson
  • Exotic DVM (journal)
  • Exotic Pet Behavior: Birds, Reptiles, and Small Mammals. Teresa Bradley Bays, Teresa Lightfoot, and Jorg Mayer
  • Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery. Katherine E. Quesenberry and James W. Carpenter
  • The 5-Minute Veterinary Consult: Ferret and Rabbit. Barbara L. Oglesbee
  • Journal of Exotic Pet Medicine
  • Notes on Rabbit Internal Medicine. Richard A. Saunders and Ron Rees Davies
  • Rabbit and Rodent Dentistry Handbook. Vittorio Capello with Margherita Gracis
  • Rabbit Medicine & Surgery. Emma Keeble and Anna Meredith
  • Textbook of Rabbit Medicine. Frances Harcourt-Brown

© Copyright 2013 by Marie Mead. Used by permission. All rights reserved.

I wish to extend my sincere gratitude to Drs. Susan Brown, Tomáš Chlebeček, and Jason Hutcheson for sharing their expertise in this article and additionally to Dr. Brown for her overall review of the article. Warm thanks to Cheryl Abbott, Sandi Ackerman, Heidi Anderson, Dr. Stephanie Crispin, Gary McConville, and Karen Witzke for their suggestions. 

Susan Brown, DVM, is the founder and former owner of Midwest Bird and Exotic Animal Hospital (originally in Westchester, Illinois) and the current owner of Rosehaven Exotic Animal Veterinary Services and The Behavior Connection (North Aurora, Illinois). She is coauthor of Self-Assessment Color Review of Small Mammals and author of numerous lay and professional writings on rabbit medicine and care; she has also lectured extensively in the United States and Europe. She is involved in exotic animal care at rescue organizations and shelters. Utilizing the principles of behavior and training, she is teaching ways for people to live in harmony with their companion animals.

Tomáš Chlebeček, DVM, is a former aerospace engineer who became a veterinarian as a result of his association with the Colorado House Rabbit Society. He received his degree from Colorado State University in 1999 and practiced at the Makai Animal Clinic in Kailua, Hawaii, before moving to the Czech Republic.

Jason Hutcheson, DVM, is the owner of For Pet’s Sake, the Avian and Exotic Animal Hospital of Atlanta. After graduating in 1998, he joined the veterinary staff at For Pet’s Sake and eventually purchased the practice from Dr. Mimi Shepherd in 2006. He treats rabbits every day for individuals and for the Georgia House Rabbit Society and has written articles for their newsletter.

  • Marie Mead

    Marie Mead has been involved in various capacities with animal rescue, advocacy, and education for over thirty years. She has made a home with special-needs rabbits and other animals, all of them rescues. Author (with collaborator Nancy LaRoche) of Rabbits: Gentle Hearts, Valiant Spirits – Inspirational Stories of Rescue, Triumph, and Joy, Marie has also written rabbit-related stories and articles for other publications.

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