Uterine adenocarcinoma is the most common cancer in unspayed female rabbits and becomes alarmingly common as does age. The first sign is often blood-tinged urine or vaginal bleeding. Spaying before middle age prevents it almost entirely, which is why early spaying is one of the most important health decisions for a female rabbit.
Last reviewed: June 2026
What Is Uterine Adenocarcinoma in Rabbits?
Uterine adenocarcinoma is a malignant cancer of the uterine lining that affects unspayed female rabbits (does), and it is the single most common tumor type in this group. The cancer develops slowly in the uterus and, if left untreated, eventually spreads to other organs—most often the lungs—where it becomes life-threatening. Because it grows over months to years, early detection while it's still confined to the uterus dramatically improves the outcome.
The risk rises steeply with age in intact does. As described in Quesenberry and Carpenter's Ferrets, Rabbits, and Rodents, the cumulative incidence in older unspayed does can reach a very high proportion, which is why spaying is so strongly recommended. Routine wellness exams help catch early signs (AEMV Pet Care Guides, 2024).
What Are the Signs of Uterine Cancer in Rabbits?
The most common early sign is blood in the urine or a blood-tinged vaginal discharge, which owners may first notice as reddish staining in the litter area. Because rabbits hide illness, this bleeding is often the first outward clue.
Signs to watch for include:
- Blood-tinged or reddish urine, or vaginal bleeding
- A firm lump or swelling in the lower belly
- Reduced appetite and gradual weight loss
- Lethargy or decreased activity
- Mammary changes, such as cysts or lumps in the mammary tissue
- Difficulty breathing in advanced cases where the cancer has spread to the lungs
Any unexplained bleeding in an unspayed doe should prompt a same-week exotic vet visit, since early surgery can be curative.
Why Does It Happen?
Uterine adenocarcinoma arises from age-related changes in the hormone-responsive uterine lining of intact female rabbits. The constant hormonal cycling of an unspayed doe over years drives abnormal cell growth that can eventually turn cancerous. There is no infectious cause—the key risk factor is simply being an intact (unspayed) female that has reached middle age. As described in Quesenberry and Carpenter's text, the disease is largely preventable through spaying.
Because the cancer is so strongly tied to intact reproductive organs, removing the uterus and ovaries early in life essentially eliminates the risk.
How Is It Treated and Prevented?
The definitive treatment is surgical removal of the uterus and ovaries (an ovariohysterectomy, or spay), which is curative if performed before the cancer spreads. For a doe already showing signs, prompt surgery offers the best chance of a cure.
- Spay surgery to remove the cancerous uterus—curative when caught early and confined
- Chest x-rays before and after surgery to check for spread to the lungs
- Supportive care to keep the rabbit eating and stable around surgery, following stasis-prevention principles (Oglesbee & Lord, 2010, JEPM)
- Preventive spaying of healthy young does (typically between 4 months and 2 years of age) to prevent the disease entirely
When the cancer has already spread to the lungs, the prognosis becomes poor, underscoring the value of prevention and early action. Spaying young does is overwhelmingly the most effective strategy.
When to See a Vet
Call your vet today if:
- You see blood-tinged urine or vaginal bleeding in an unspayed doe
- You feel a lump or swelling in your rabbit's lower belly
- Your rabbit is losing weight or seems less active
Go to the ER immediately if:
- Your rabbit has heavy, ongoing bleeding
- Your rabbit has stopped eating or passing stool
- Your rabbit is weak, collapsed, or struggling to breathe
- The belly is rapidly enlarging or your rabbit is in obvious distress
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Frequently Asked Questions
How common is uterine cancer in unspayed rabbits?
It is the most common cancer in intact female rabbits, and the risk climbs sharply with age—studies cited in exotic medicine texts report that a majority of unspayed does over several years of age develop uterine adenocarcinoma. This very high lifetime risk is the main reason veterinarians strongly recommend spaying female rabbits while they are young.
Does spaying prevent uterine cancer in rabbits?
Yes—removing the uterus and ovaries through spaying essentially eliminates the risk of uterine adenocarcinoma, since the cancer arises from uterine tissue. Spaying young, healthy does (typically between about 4 months and 2 years of age) is considered one of the most important preventive health measures for female rabbits and also prevents other reproductive problems.
How much does rabbit spay surgery or cancer treatment cost?
A preventive spay by an exotic vet typically costs $250–600. If cancer is suspected, diagnostics like bloodwork and chest x-rays add $200–500, and surgery to remove a cancerous uterus generally runs $400–900 or more. Because exotic procedures carry a premium and emergencies cost more, preventive spaying is both safer and more economical.
Can rabbit uterine cancer be cured?
Yes, if caught early. When the cancer is still confined to the uterus, surgical removal (a spay) is usually curative. The prognosis worsens significantly once it spreads to the lungs or other organs, which can happen over time. This is why prompt action at the first sign of bleeding—and ideally preventive spaying—matters so much.
What does blood in my rabbit's urine mean?
Blood-tinged urine in an unspayed female rabbit is a classic warning sign of uterine disease, including adenocarcinoma, though bladder stones or infections can also cause it. True red urine from pigments in food can look similar but is harmless. Because the causes differ greatly in seriousness, any reddish urine warrants an exotic vet exam to determine the source.
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