Rabbit Fibroma Virus in Rabbits: Skin Lumps and What They Mean

Quick Answer
  • Rabbit fibroma virus, also called Shope fibroma virus, is a poxvirus that can cause soft, clearly defined lumps under the skin, most often on the legs, feet, and ears.
  • These growths may persist for weeks to months and can sometimes regress on their own, but any new lump still needs a veterinary exam because abscesses, papillomas, trauma, and cancer can look similar.
  • Domestic rabbits are not the usual natural host. Risk is higher where rabbits may be exposed to wild cottontails and biting insects such as mosquitoes or fleas.
  • Diagnosis often starts with a hands-on exam and may include needle sampling, biopsy, or histopathology to confirm what the lump is.
  • Typical US cost range for an exam and basic lump workup is about $90-$350; biopsy, sedation, surgery, or pathology can bring the total to roughly $400-$1,500+ depending on complexity and location.
Estimated cost: $90–$1,500

What Is Rabbit Fibroma Virus in Rabbits?

Rabbit fibroma virus, often called Shope fibroma virus, is a poxvirus linked to benign skin tumors called fibromas. In rabbits, these usually begin as a mild thickening under the skin and then develop into a soft, well-defined swelling. Classic locations include the legs, feet, and ears.

This virus is found naturally in cottontail rabbits. Domestic rabbits are not the usual host, but they can be affected in areas where the virus is present in wild rabbit populations and where insect exposure makes spread more likely. That means a pet parent may notice a lump on an otherwise normal rabbit and not realize it could be related to a viral skin growth.

The reassuring part is that these fibromas are often self-limiting, meaning they may shrink over time as the rabbit mounts an immune response. Still, a lump should never be assumed to be harmless at home. Rabbits commonly get abscesses, and other skin masses can also look similar early on, so your vet needs to sort out what the lump actually is.

Symptoms of Rabbit Fibroma Virus in Rabbits

  • Soft, clearly demarcated lump under the skin
  • Mild thickening of tissue before a visible swelling forms
  • Lumps on the ears, legs, or feet
  • Single or multiple fleshy skin growths
  • Irritation, rubbing, or surface trauma over the lump
  • Trouble moving, eating, or seeing if a growth is large or in a difficult location
  • Redness, discharge, odor, or pain suggesting secondary infection or a different diagnosis such as an abscess
  • Reduced appetite, lethargy, or rapid enlargement of a mass

Many rabbits with fibroma virus have localized skin lumps and otherwise seem fairly normal. The concern is that skin masses in rabbits are not all the same. A viral fibroma can look less dramatic than a painful abscess, but both can start as a firm or soft swelling.

You should be more concerned if the lump is growing quickly, becomes ulcerated, interferes with walking, grooming, eating, or vision, or if your rabbit seems painful, quiet, or off food. Rabbits can decline quickly when they stop eating, so any lump paired with appetite changes should move up the urgency list and be checked by your vet promptly.

What Causes Rabbit Fibroma Virus in Rabbits?

Rabbit fibroma virus is caused by a poxvirus. In rabbits, the best-known form is Shope fibroma virus. Wild eastern cottontails are the natural host, and local outbreaks have been described in the eastern and Midwestern United States.

Spread is thought to happen mainly through biting insects, especially mosquitoes and fleas, and through contact with injured skin. For pet rabbits, risk may increase if they spend time outdoors, live where wild rabbits are common, or are housed in ways that allow insect exposure.

This is one reason your vet may ask detailed questions about your rabbit's environment, including outdoor access, insect control, and any possible contact with wild rabbits. Even then, not every skin lump in a rabbit is viral. Abscesses, cysts, papillomas, trauma, and tumors can all be part of the differential list.

How Is Rabbit Fibroma Virus in Rabbits Diagnosed?

Diagnosis starts with a physical exam and a close look at the lump's location, texture, number, and rate of growth. Your vet will also consider your rabbit's history, including outdoor exposure, insect bites, and possible contact with wild rabbits. In some cases, the appearance is suggestive, but appearance alone is not enough to confirm a fibroma.

To tell a fibroma from an abscess or another mass, your vet may recommend needle sampling, cytology, or a biopsy. The most reliable confirmation is usually histopathology, where tissue is examined under a microscope. Histology can show the characteristic changes seen with Shope fibroma virus.

If the lump is in a tricky area or your rabbit is uncomfortable, sedation may be needed for safe sampling. Your vet may also recommend additional testing if there are signs of infection, multiple masses, or concern for another disease process. The goal is not only to name the lump, but also to decide whether monitoring, removal, or supportive care makes the most sense for your rabbit.

Treatment Options for Rabbit Fibroma Virus in Rabbits

Spectrum of Care means you have options. Here are treatment tiers at different price points.

Budget-Conscious Care

$90–$350
Best for: Small, stable lumps in a rabbit who is eating normally and has no signs of pain, infection, or mobility problems.
  • Rabbit-savvy veterinary exam
  • Measurement and photo monitoring of the lump
  • Discussion of likely differentials and home monitoring plan
  • Basic supportive care if the rabbit is otherwise bright, eating, and comfortable
  • Environmental changes to reduce insect exposure
Expected outcome: Often fair to good if the mass truly is a fibroma and remains uncomplicated. Some lesions may regress over time.
Consider: Lower upfront cost, but less diagnostic certainty. This approach can miss an abscess or another tumor if the lump changes or was misidentified early.
Most Common

Recommended Standard Treatment

$350–$900
Best for: Most pet rabbits with a new skin lump, especially when the diagnosis is uncertain or the mass is growing, rubbing, or in a sensitive location.
  • Rabbit-savvy exam and full skin-mass assessment
  • Fine-needle sampling or cytology when appropriate
  • Biopsy or tissue submission for histopathology
  • Pain control or wound care if the lesion is irritated
  • Recheck exam to monitor growth, regression, or complications
Expected outcome: Good in many uncomplicated cases once the lump is identified and monitored appropriately.
Consider: More cost and sometimes sedation are needed, but this tier gives much better diagnostic confidence and helps guide whether surgery is necessary.

Advanced / Critical Care

$900–$1,500
Best for: Large, ulcerated, infected, fast-growing, or poorly located masses, or cases where pet parents want the most complete diagnostic and treatment plan.
  • Advanced imaging or surgical planning for difficult masses
  • Sedation or anesthesia for biopsy or complete removal
  • Mass excision with pathology submission
  • Hospitalization, assisted feeding, and fluid support if the rabbit is not eating or has post-procedure needs
  • Treatment of secondary infection, ulceration, or functional problems affecting movement, vision, or grooming
Expected outcome: Often good if the lesion can be managed before major complications develop, though outcome depends on the true diagnosis and the mass location.
Consider: Highest cost range and more intensive handling. Anesthesia and surgery carry added risk in rabbits, so the plan should be individualized with your vet.

Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.

Questions to Ask Your Vet About Rabbit Fibroma Virus in Rabbits

Bring these questions to your vet appointment to get the most out of your visit.

  1. Does this lump look more like a fibroma, an abscess, a papilloma, or another kind of mass?
  2. What tests would give us the most useful answer first: monitoring, needle sampling, or biopsy?
  3. Is this lump in a location that could affect walking, grooming, eating, or vision?
  4. Does my rabbit need sedation for sampling, and what are the risks and benefits?
  5. If we monitor instead of removing it now, what exact changes should make me call right away?
  6. Could there be a secondary infection, and what signs should I watch for at home?
  7. How can I reduce mosquito and flea exposure for my rabbit safely?
  8. What is the expected cost range for the next step, including pathology if tissue is submitted?

How to Prevent Rabbit Fibroma Virus in Rabbits

Prevention focuses on lowering exposure to the virus and the insects that may spread it. For many pet rabbits, the most practical steps are to limit contact with wild rabbits, reduce mosquito and flea exposure, and keep housing clean, dry, and secure. Outdoor time may need to be adjusted if your area has heavy insect activity or known wild rabbit populations.

Ask your vet which rabbit-safe parasite prevention and environmental controls make sense in your region. Not every dog or cat product is safe for rabbits, so this is not a do-it-yourself medication decision. Screens, prompt cleaning, and avoiding areas visited by wild rabbits can all help reduce risk.

It also helps to check your rabbit's skin regularly during grooming and handling. Early detection matters. A small lump that is photographed, measured, and examined early is usually easier to monitor than a mass that has already become irritated, infected, or large enough to interfere with normal rabbit behavior.

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