Uterine Adenocarcinoma in Rabbits
Endometrial adenocarcinoma
Also known as: Rabbit uterine adenocarcinoma, Endometrial adenocarcinoma, Uterine carcinoma
In short
Endometrial adenocarcinoma
Also known as: Rabbit uterine adenocarcinoma, Endometrial adenocarcinoma, Uterine carcinoma
In short
Uterine adenocarcinoma is the most common cancer affecting female rabbits, particularly unspayed females over three years of age. This slow-growing but malignant tumor can be cured with early surgical intervention, but it carries a poor prognosis if it spreads to other organs.

TL;DR. Uterine adenocarcinoma is a highly common and malignant uterine cancer in unspayed female rabbits over three years old, but it is entirely preventable through early spaying.

Unlike many other mammals, female rabbits possess a duplex uterus with two separate uterine horns and cervices.
Uterine adenocarcinoma (specifically endometrial adenocarcinoma) is the most common tumor diagnosed in female rabbits. It is a slow-growing but highly malignant cancer that originates in the endometrium, which is the inner glandular lining of the rabbit's uterus. Because the disease progresses gradually, it often goes unnoticed by owners in its early stages. However, as the tumor grows, it eventually invades the deeper layers of the uterine wall and can spread (metastasize) to other vital organs, most commonly the lungs and the liver.
To understand this disease, it helps to understand the unique anatomy of the female rabbit's reproductive tract. Unlike dogs, cats, and humans, female rabbits have a "duplex" uterus. This means they possess two entirely separate uterine horns, each with its own cervix opening into a single vagina. Uterine adenocarcinoma can develop in one or both of these uterine horns. Over time, the tumor causes the uterine tissue to become thickened, cystic, and highly prone to bleeding.
This cancer is a significant concern for rabbit owners because of its remarkably high prevalence. Veterinary studies indicate that up to 50% to 80% of intact (unspayed) female rabbits will develop uterine adenocarcinoma by the time they reach three to four years of age. Understanding the early signs of this disease and the critical importance of preventive care is essential for ensuring your rabbit lives a long, healthy life.
The primary risk factor for developing uterine adenocarcinoma is leaving a female rabbit intact (unspayed) as she ages. Age is the single most significant variable; while the disease is rare in rabbits under two years of age, the risk increases dramatically once a rabbit passes her third birthday.
The underlying cause of the tumor is closely linked to chronic hormonal stimulation. Rabbits are induced ovulators, meaning they do not experience a regular, cyclic estrous cycle like many other mammals. Instead, they remain in a state of persistent estrogen dominance unless they are bred. Over several years, this constant hormonal stimulation causes progressive, abnormal changes in the endometrium. This process typically begins as cystic endometrial hyperplasia (a benign thickening of the uterine lining), which gradually transitions into cellular changes, localized carcinoma, and eventually invasive, metastatic adenocarcinoma.
While any unspayed female rabbit is at high risk, certain breed predispositions have been identified. Retrospective veterinary studies suggest that the Dutch Rabbit and the Havana breed may have a higher genetic susceptibility to developing this tumor compared to other breeds. However, no intact female rabbit of any breed is considered safe from this disease as she ages.
In its earliest stages, uterine adenocarcinoma is virtually silent, showing no outward physical signs. As the tumor grows and begins to alter the uterine tissue, several clinical signs will emerge. Owners should monitor their rabbits closely for the following symptoms:

Lethargy and a hunched posture can be subtle signs of pain or anemia caused by uterine tumors in rabbits.
Diagnosing uterine adenocarcinoma requires a systematic veterinary evaluation. Because rabbits are prey animals, they instinctively hide signs of illness until they are severely compromised, making professional diagnostic testing essential.
Your vet will begin with a thorough physical examination, including careful palpation of your rabbit's abdomen. An enlarged, firm, or nodular uterus is highly suspicious in an intact female. To confirm the diagnosis and assess whether the cancer has spread, your vet will recommend several key diagnostic tests:

Abdominal ultrasonography is a key diagnostic tool used to visualize uterine thickening and identify tumor masses.
Treating uterine adenocarcinoma depends heavily on whether the cancer has metastasized to other parts of the body.
For rabbits with localized disease (where the cancer is strictly confined to the uterus), the primary and most effective treatment is an ovariohysterectomy (spay). During this surgical procedure, the veterinarian removes both ovaries and the entire duplex uterus, including both cervices.
Performing surgery on an exotic pet requires specialized veterinary care. Your vet will use tailored anesthetic protocols, provide active warming to maintain the rabbit's body temperature, and administer intravenous fluids to support blood pressure. If the tumor is removed entirely before it has metastasized, the surgery is curative.
If the rabbit is undergoing surgery, or if the cancer has already spread and the owner is pursuing palliative care to keep the rabbit comfortable, medical management is essential. This typically involves:
The long-term outlook for a rabbit with uterine adenocarcinoma is highly variable and depends entirely on the timing of the diagnosis:
Uterine adenocarcinoma is one of the few highly common, malignant cancers in veterinary medicine that is 100% preventable.
The absolute gold standard for prevention is routine ovariohysterectomy (spaying) of all female rabbits at a young age. Most exotic veterinarians recommend spaying female rabbits between 4 and 6 months of age, once they reach sexual maturity. Spaying at this stage is a safe, routine procedure that completely eliminates the risk of uterine adenocarcinoma, as the target tissue is removed before abnormal cellular changes can ever begin.
In addition to preventing cancer, spaying your rabbit offers several other significant health and behavioral benefits:
If you adopt an older, unspayed female rabbit, it is highly recommended to schedule a veterinary consultation to discuss a preventative spay, even if she is over two years old, provided she is deemed a safe anesthetic candidate after a thorough pre-operative screening.
Because rabbits hide illness so effectively, you must act quickly if you notice any changes in their behavior or physical appearance.
Contact your veterinarian immediately if you observe any of the following emergency red flags:
Schedule an urgent appointment if you notice more gradual changes, such as a slowly declining appetite, progressive weight loss, pale gums, or intermittent pink-tinged urine.
If you own a Dutch Rabbit or a Havana, you should be extra vigilant. While all intact female rabbits face an incredibly high risk of developing uterine cancer as they age, these specific breeds have a suspected genetic predisposition that may make them even more vulnerable.
If you have a young female Dutch or Havana rabbit, prioritizing a preventative spay between 4 and 6 months of age is the single most important healthcare decision you can make for her. If you own an older, intact female of these breeds, discuss diagnostic screening (such as abdominal ultrasound) with your veterinarian as soon as possible to check for early signs of uterine changes.
Guidance on the diagnosis, treatment, and prevention of uterine adenocarcinoma in rabbits is derived from standard-of-care veterinary knowledge and established reference texts in exotic animal medicine, including:
Treatment must be prescribed by a licensed veterinarian based on your pet. Specific drug doses are intentionally not shown here.
Uterine adenocarcinoma is the most common cancer affecting female rabbits, particularly unspayed females over three years of age. This slow-growing but malignant tumor can be cured with early surgical intervention, but it carries a poor prognosis if it spreads to other organs.
Hematuria or bloody vaginal discharge、Abdominal mass or uterine enlargement、Pale mucous membranes、Anorexia and weight loss、Dyspnea、Lethargy
Histopathology of the uterus、Abdominal ultrasonography、Thoracic and abdominal radiography
Treatment must be prescribed by a licensed veterinarian based on your pet. Specific drug doses are intentionally not shown here.
This article is for general education and is not a substitute for professional veterinary advice. If your pet is unwell, please consult a veterinarian.
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