singapore rabbits

rabbit mammary tumours, the SG owner's monthly home check

updated 14 May 2026

mammary tumours in rabbits kill quietly. a lump forms under a thick layer of belly fur, sits there for weeks or months while the owner sees nothing, and by the time it is noticed the mass has grown large or spread to the lungs. most owners only discover it when the rabbit starts grooming the area obsessively, or when a vet finds it during an annual exam. in SG’s climate, fur density in Angora and Lionhead crosses can make the hiding even worse.

the reason this matters so much is prognosis. a mammary adenocarcinoma caught at 1 cm with no lymph node involvement and clear lung X-rays is a rabbit that can be cured with surgery. the same tumour caught at 4 cm, bilateral, with satellite nodules, is a rabbit you are trying to buy time for. the difference between those two scenarios is often just one person doing a 5-minute belly check once a month. this guide teaches you how.

why mammary tumours matter in unspayed does

unspayed does (female rabbits) face a disproportionately high lifetime cancer risk. uterine adenocarcinoma is the most commonly cited statistic, affecting up to 60-80% of unspayed does over age 4. but mammary tumours are often grouped with that number or mentioned as a separate late-stage concern, which undersells how common they are.

mammary adenocarcinoma is the dominant type. unlike in dogs, where roughly half of mammary tumours are benign, rabbit mammary tumours skew heavily malignant. studies in laboratory rabbit populations put malignancy rates at 80% or higher. that means if you find a lump and it turns out to be a mammary tumour, the odds are already against you. speed is the variable you can still control.

mammary tumours also carry a risk of local spread to axillary and inguinal lymph nodes, and distant metastasis to the lungs is well-documented. by the time a rabbit is breathing with effort or losing weight, the cancer has usually been travelling for months. catching it early, before regional spread, is what makes surgery curative rather than palliative.

bucks can develop mammary tumours too, though far less commonly. they have rudimentary mammary tissue and the same hormonal predispositions apply in lesser form. it is worth checking bucks during your routine health check, but the risk is low enough that this guide focuses primarily on does.

the anatomy — 4-5 mammary chains in a doe (and where they sit)

does have between 4 and 5 pairs of mammary glands arranged in two parallel chains running along either side of the midline of the belly, from just behind the armpits down to the groin. each pair is a gland, and each gland has a nipple visible on the surface.

the chain layout from front to back:

  • thoracic glands — sitting behind the front legs, roughly at chest level. often the ones owners miss completely because they assume that area is chest, not belly.
  • cranial abdominal glands — mid-belly, above the navel region. most commonly where early tumours are found.
  • caudal abdominal glands — lower belly, moving toward the hindquarters.
  • inguinal glands — in the groin region, close to where the hind legs meet the body. often obscured by a thick dewlap or fur fold.

some does have a fifth pair at a position between thoracic and cranial abdominal. breed variation exists, and larger breeds tend to have more pronounced gland tissue.

the important thing to understand is that the glands are bilateral but not always symmetric. a tumour can appear in one gland while the mirror gland stays normal. checking only one side is not sufficient.

the monthly home check — step by step

this takes 5 minutes once you have practiced it twice. do it on the same day each month, tied to something you already do, so it does not slip.

step 1: position the rabbit.

the two reliable positions are the burrito hold and the supine trance position. for most rabbits, trancing (placing them on their back in a V-shaped support) works well because it exposes the full belly. use a folded towel as a cradle. some rabbits dislike being on their back; for those, have a second person hold the rabbit upright against their chest while you reach around to the belly. never force a rabbit into a position that causes it to struggle; struggling means you miss things and you stress the rabbit.

step 2: clear the fur visually.

part the belly fur in sections, working from the armpits down to the groin. in SG humidity, fur can mat slightly, especially in the inguinal region. look for any visible swelling, redness, or skin discolouration over a nipple before you start touching.

step 3: palpate each gland.

use the pads of your index and middle fingers together, not your fingertips. press gently but with enough depth to feel past the fur and superficial fat layer. you are looking for any firm structure that does not feel like soft fat. work each gland in a small circular motion, starting just behind the nipple and moving outward.

palpate in order: right thoracic, left thoracic, right cranial abdominal, left cranial abdominal, right caudal abdominal, left caudal abdominal, right inguinal, left inguinal. do not skip glands because you are tired or the rabbit is wriggly. inguinal glands are the easiest to skip and the sneakiest for tumour location.

step 4: check the nipples themselves.

squeeze each nipple very gently between two fingers. you should feel nothing come out in a non-pregnant, non-lactating doe. any discharge, especially milky, bloody, or brown, is an immediate vet flag, regardless of whether you feel a lump beneath.

step 5: note and log.

keep a simple note on your phone with the date and any findings. “all clear, no lumps” is a valid entry. the value of logging is that if you find something next month, you know when the last clear check was, which tells the vet how fast the mass appeared.

what a normal vs concerning lump feels like

rabbits have a lot of normal structures in the belly that owners feel for the first time and panic about. knowing what is normal helps you stay calibrated.

normal findings:

  • soft, compressible fat pads under each gland. in overweight does, these can be substantial and sit like soft cushions under the nipple region. they compress easily under finger pressure and feel uniform.
  • the spine and hip bones if the rabbit is lean, felt through the belly from the side.
  • cecum contents — the cecum is the large fermentation chamber in the lower right belly. it moves, feels slightly grainy or liquid-filled, and shifts with bowel activity. it is not fixed.
  • in pregnant or recently pregnant does, gland tissue is enlarged uniformly across the chain and feels firm but symmetrical. if your doe is not pregnant and has never been pregnant, this finding is unusual.

concerning findings:

  • a discrete, firm nodule that does not compress when you press it. unlike fat, which squishes, a mammary tumour feels solid, almost like a grape or a small pebble under the tissue.
  • a mass that is fixed to the surrounding tissue. benign masses tend to move slightly when you push them. malignant ones become adherent to the skin or underlying tissue as they grow. if you feel something that does not slide freely under your fingers, that is a flag.
  • asymmetry. if the right thoracic gland feels clearly different from the left, that asymmetry matters.
  • growth rate. a lipoma or cyst can sit unchanged for months. a mammary tumour typically grows, and if you can feel it getting bigger week over week, that is urgent.
  • skin changes over a mass. redness, warmth, or ulceration of the skin directly over a lump suggests an aggressive tumour or a secondary infection.

the differential — abscess, lipoma, cyst, mastitis, mammary tumour

not every belly lump is cancer. a SG exotic vet will work through a differential before assuming the worst.

abscess. rabbits are prone to abscesses from small wounds, dental disease extension, or injection sites. an abscess in the mammary region will often feel warm, may have discharge if it has tracked to the surface, and the rabbit will be reactive to touch. abscesses can look very similar to tumours on palpation alone, which is why FNA or aspiration is useful early. you can read more about what vets look for in our rabbit abscess guide.

lipoma. fatty benign tumours that feel soft and moveable. they are less common in rabbits than in dogs but do occur. a lipoma stays soft under pressure, does not grow rapidly, and FNA will show fat cells only. the frustrating part is that you cannot tell a lipoma from an early mammary tumour by feel alone.

cyst. fluid-filled, compressible, smooth-walled. associated with ovarian cysts or dilated mammary ducts. tends to feel fluctuant (like a water balloon) rather than solid. see our guide on ovarian cysts in senior does for related context.

mastitis. infection of the mammary gland. occurs in lactating does or pseudo-pregnant does. the affected gland is hot, swollen, and painful. the rabbit may be systemically unwell, feverish, and off food. this is a medical emergency requiring antibiotics, not a surgical case.

mammary tumour. usually firm, discrete, relatively painless early on, possibly bilateral, with nipple discharge or skin changes in advanced cases. growth rate is the key distinguishing feature in an office setting.

the critical point is that no owner or vet can confidently call any of these by palpation alone. you need cytology or histology to know what you are dealing with.

when to escalate to a vet

if you find any of the following, book a consult within the week, not next month:

  • any discrete firm lump you cannot explain, even if small. a 0.5 cm lump that turns out to be benign is worth SGD 80 for the peace of mind and baseline. the same 0.5 cm lump that is caught early is the best-case surgical scenario if it is malignant.
  • any lump that has grown noticeably between two monthly checks.
  • nipple discharge of any colour.
  • skin ulceration, crusting, or redness over a mammary gland.
  • the rabbit is licking or grooming the belly area more than usual. rabbits are not vocal about pain, but persistent attention to one area is a behavioural signal.
  • bilateral lumps. two masses makes a benign explanation less likely.
  • any systemic signs in a rabbit with a known lump: weight loss, reduced appetite, laboured breathing. those are metastasis flags.

do not wait to see if the lump grows before going in. “watch and wait” is appropriate for a confirmed lipoma with cytology backing it. it is not appropriate for an undiagnosed firm mammary mass in an unspayed doe. every week of waiting is a week for a malignant tumour to progress.

the diagnostic workup — palpation, FNA, biopsy, X-ray for lung metastasis

when you present to a SG exotic vet with a mammary lump, here is what a proper workup looks like.

clinical palpation. the vet repeats your assessment with trained hands. they note size in millimetres, location within the chain, mobility, skin involvement, and whether regional lymph nodes are enlarged. axillary (armpit) and inguinal (groin) nodes that are palpable and firm suggest regional spread.

fine needle aspirate (FNA). cost in SG is SGD 80-150. a thin needle is inserted into the mass and cells are aspirated onto a slide. the slide goes to a cytologist. FNA is quick, requires no sedation, and gives you a rapid answer. the limitation is that it can miss focal areas of malignancy within a mixed tumour, and some tumours are poorly cellular and give inconclusive results. a negative FNA does not rule out malignancy in a rabbit with a suspicious mass.

biopsy (histopathology). cost SGD 200-400. a core needle biopsy or small excisional sample gives a tissue architecture view that FNA cannot provide. it distinguishes adenoma from adenocarcinoma and can give grading information. if FNA is inconclusive, a biopsy is the next step before deciding on surgery.

chest X-rays for metastasis screening. cost SGD 80-150 for a 2-view set. mammary adenocarcinoma spreads to the lungs. before surgery, your vet needs to know whether there are pulmonary nodules, because that changes both the prognosis and the surgical calculus. a rabbit with clear lung X-rays and a small primary tumour is a good surgical candidate. a rabbit with multiple lung nodules on X-ray is being offered palliative surgery, not curative surgery, and that changes the consent conversation entirely.

abdominal ultrasound. sometimes added to check for liver metastasis or associated uterine disease. not mandatory for every case, but useful in older does where concurrent uterine pathology is common.

the workup total in SG, including vet consult, FNA, and chest X-rays, typically runs SGD 250-400 before surgery is even discussed.

surgical options — lumpectomy alone vs lumpectomy + spay

once cytology or histopathology confirms a mammary tumour, surgery is the primary treatment. there are two approaches.

lumpectomy alone. removal of the mass with a margin of surrounding tissue. indicated when the tumour is small, the rabbit is a poor anaesthetic candidate, or the owner is not ready for a more extensive procedure. the significant limitation in an unspayed doe is that leaving the reproductive tract intact means the same hormonal environment that triggered the first tumour remains. recurrence rates are higher with lumpectomy alone.

lumpectomy + spay (the standard combined approach in SG). removal of the tumour plus ovariohysterectomy (full spay) in the same surgical session. the spay removes the hormonal drive for new tumour formation and simultaneously treats any concurrent uterine disease, which in an unspayed doe presenting with mammary tumours is not a low probability event. for any unspayed doe with a mammary tumour who is a reasonable anaesthetic candidate, most SG exotic vets will recommend the combined approach. it is one anaesthetic event, one recovery, and better long-term outcomes.

the exception is when the rabbit is very old, has significant concurrent disease, or when multiple large tumours make wound closure complex. in those cases the vet will stage the procedures or recommend palliative management only.

in cases with large tumours or bilateral involvement, partial mastectomy (removal of one or more entire glands rather than just the mass) is sometimes performed. this is a more extensive surgery with more complex wound management but offers better local control margins.

what the surgery looks like — pre-op, anaesthesia in SG, expected duration, costs

pre-op. blood work is standard before rabbit surgery in SG, especially for does over 3 years. a basic panel checks kidney and liver values, which affect anaesthetic drug dosing. fasting is not standard for rabbits (they cannot vomit and GI stasis risk from fasting outweighs the benefit), though some vets ask owners to remove hay 2-4 hours before to reduce GI fill.

anaesthesia. rabbit anaesthesia carries real risk, but in the hands of a rabbit-experienced exotic vet at a centre equipped for small mammal surgery, the risk is managed. SG centres regularly performing this surgery include Beecroft Animal Specialist Centre, Animal Recovery Centre (ARC), Mount Pleasant (Gelenggang), Brighton Veterinary Surgery, and Frankel Veterinary Clinic. the key is asking directly whether the vet has performed rabbit spays and mammary surgeries and how frequently. you can read more about anaesthetic risk in our rabbit anaesthesia guide.

duration. a straightforward lumpectomy alone takes 30-45 minutes. a combined lumpectomy plus spay runs 60-90 minutes depending on tumour size, adhesions, and whether the uterus shows complicating pathology like pyometra. surgeons at centres experienced in rabbit reproductive surgery work faster and with less tissue manipulation, which matters for recovery.

costs. the total surgical cost in SG for combined lumpectomy plus spay ranges from SGD 1,000 to SGD 2,500. the variance depends on:

  • whether it is a single small lumpectomy or a partial mastectomy
  • whether uterine disease complicates the spay
  • post-op hospital stay, which is typically 1-2 nights for combined procedures
  • pain medication, antibiotics, and wound care on discharge

a straightforward single-gland lumpectomy alone at the lower end runs SGD 800-1,200. combined procedures at referral centres with intensive post-op monitoring sit at the upper end. ask for a written estimate before consenting to surgery. check our rabbit spaying cost guide for baseline SG pricing context.

post-op care at home — incision, mammary chain healing, drain management

the first 48-72 hours after returning home are the most critical.

housing. a clean, flat-bottomed enclosure without bedding that can get into the wound. fleece liners work well. the rabbit should not be able to jump; confine to a single level if your setup is multi-tier. do not return it to a shared enclosure with other rabbits until the wound is fully closed.

incision monitoring. check the wound twice daily. you are looking for redness spreading beyond the wound margins, discharge that is thicker than a small amount of clear or pale yellow fluid, swelling that is increasing rather than decreasing, or any gap in the wound edges. a small amount of redness and swelling in the first 24 hours is expected. progression after 48 hours is a call to the vet.

drain management. some surgeons place a passive drain (a small tube or wick) in larger excision cavities to prevent fluid accumulation. if your rabbit has a drain, the vet will give specific instructions on when it is removed (typically 3-5 days post-op). keep the area around the drain exit clean. do not remove the drain yourself.

preventing licking and chewing. rabbits groom obsessively and will target an incision. a properly fitted e-collar (elizabethan collar) or recovery suit is usually recommended. many rabbits tolerate a soft fabric recovery suit better than a rigid cone. check our post-op recovery guide for collar-fitting tips.

eating and GI function. the first sign of surgical recovery in a rabbit is eating. a rabbit that eats hay within a few hours of coming home is doing well. a rabbit that has not eaten by the next morning and has produced no fecal pellets needs a call to the vet. GI stasis is the most common post-surgical complication and is more immediately dangerous in a rabbit than the wound itself.

pain management. your rabbit should go home with meloxicam (an NSAID) and possibly buprenorphine or tramadol for the first few days. do not skip doses even if the rabbit seems comfortable. rabbits mask pain effectively. see our medication administration guide for how to syringe-feed a rabbit that resists oral medication.

follow-up appointment. scheduled typically at 7-10 days for suture removal or wound check if sutures are absorbable. do not skip this appointment even if the wound looks fine. the vet checks internal healing and can catch early complications that are not visible on the surface.

prognosis by stage and tumour type

benign tumours (adenoma). rare in rabbits, but when present and fully excised with margins, prognosis is excellent. the same risk factors for new tumour formation remain unless spayed, so spay at the time of surgery is still recommended.

malignant adenocarcinoma, no regional spread, no metastasis. this is the best-case malignant scenario. small tumour, clear margins on histopathology, negative lymph nodes, clear chest X-rays. with combined lumpectomy plus spay and complete surgical margins, median survival times in reported cases are 12-24 months, with some rabbits reaching 3-4 years post-surgery. not a guarantee, but a meaningful extension of quality life.

regional lymph node involvement. lymph nodes containing tumour cells mean the cancer has started migrating. surgical cure becomes less likely. some rabbits still do well post-surgery for extended periods, but recurrence risk is higher and monitoring needs to be more frequent.

lung metastasis present at diagnosis. surgery may still be offered to remove the primary tumour and improve quality of life, but the disease is systemic. prognosis shifts from months to weeks in aggressive presentations. the focus moves toward comfort care. our quality of life scale guide is worth reading at this stage.

bilateral tumours. bilateral presentation suggests either multicentric disease or a highly hormonal tumour environment. surgery can still be attempted, but the scale of the procedure is larger, recovery is harder, and the probability of residual disease is higher.

staging is not a verdict, it is information. knowing the stage helps you make informed decisions about surgery, about post-op monitoring frequency, and about when to shift priorities toward quality of life rather than curative treatment.

the spay-young prevention argument

the most effective intervention for mammary tumours is not catching them early. it is preventing them from forming at all.

spaying a doe before her first heat, ideally between 4-6 months, dramatically reduces the lifetime risk of mammary tumour formation. the mechanism is the same as in cats and dogs: oestrogen and progesterone drive mammary gland proliferation, and cycling hormone levels over years create cumulative DNA damage in mammary tissue. removing the ovaries before that hormonal exposure accumulates cuts the risk at the source.

the spay-before-first-heat data in rabbits is less robust than in cats (where spaying before the first heat reduces mammary tumour risk to nearly zero), but the principle is supported by veterinary consensus. even spaying at age 1-2 years, before any tumour has appeared, significantly reduces risk compared to remaining intact.

in SG, the cultural norm for pet rabbit management is evolving. rabbits are increasingly kept as indoor companions rather than hutch animals, and owner engagement in preventive care has grown. but many does remain unspayed because owners believe rabbits do not need surgery if they are not breeding, or because they are worried about anaesthetic risk. both assumptions are worth revisiting.

anaesthetic risk in a healthy young rabbit is lower than in a senior rabbit with concurrent disease. the riskiest time to spay a rabbit is after it has already developed uterine disease or a mammary tumour. see uterine cancer in does for the full case on early spaying.

if your doe is under age 2 and unspayed, the conversation with a rabbit-experienced SG exotic vet about elective spay is worth having. the short-term surgical risk in a healthy young rabbit is real but small. the long-term cancer risk of staying intact over a 5-10 year lifespan is substantially larger.

what owners often get wrong

waiting for the lump to grow before acting. the most common delay. owners find something suspicious, decide to monitor at home for a few weeks, and return to the vet 2-3 months later with a lump that has tripled in size. growth rate is itself a diagnostic finding. if you find a lump and you cannot explain it, go to the vet now. a clear FNA at SGD 80 is worth it.

assuming “she seems fine” means the tumour is benign. rabbits mask discomfort remarkably well. a rabbit eating normally, grooming, and running around can have an actively growing malignant tumour. behaviour is not a reliable indicator of tumour severity at early stages.

skipping the chest X-ray because the tumour feels small. micrometastases do not always show on X-ray, but macronodular spread usually does. skipping the X-ray means proceeding with curative-intent surgery without knowing whether the disease is already systemic. that is a decision you should make with full information, not a step to cut out to save SGD 100.

doing lumpectomy only and skipping the spay. understandable if cost or anaesthetic concerns are real, but without removing the hormonal environment, recurrence in the same or adjacent glands is significantly more likely. if the rabbit is healthy enough for lumpectomy, it is usually healthy enough for the combined procedure. discuss it explicitly with the vet rather than defaulting to the shorter surgery.

not starting monthly checks until the rabbit is old. mammary tumours can appear in does as young as 3-4 years. some cases in literature are in does under 3 years. monthly home checks should start from the time you bring home an adult unspayed doe, not from age 5 onwards when “senior” care begins. early checking is cheap insurance.

this guide is for educational purposes and does not replace a consult with a rabbit-experienced exotic vet. if you find a lump, book an appointment; do not use this article to self-diagnose or delay care. mammary tumours in rabbits are time-sensitive. early action makes a material difference in outcome.

community-sourced information, not veterinary advice. for medical issues, see a licensed SG exotic vet — start with our vet directory.

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