Uterine diseases

When it comes to spaying, uterine diseases are frequently brought up and are often grouped together under general terms like uterine cancer or uterine abnormalities. This page is designed to provide detailed information about different conditions, helping pet owners better understand these diseases and make well-informed decisions about treatment.

Information on the Estrous Cycle and Spaying in Female Rabbits

Since rabbits are highly adapted for reproduction, sex hormones play a significant role in their physiology. In pet rabbits, issues related to these hormones are not uncommon.

Both non-neoplastic and cancerous diseases occur in rabbits with similar frequency, and combinations of both are also possible. Among the non-neoplastic conditions, hyperplasia and inflammatory changes (including pyometra, hydrometra, mucometra, and hematometra) are the most common. The most frequently occurring neoplastic condition by far is adenocarcinoma

Diagnosis of Uterine Diseases in Rabbits

Palpation:
In young, healthy rabbits, the uterus is typically either not palpable or felt as a thin strand. A thickened uterus is considered abnormal and may indicate fatty deposits (in older or overweight rabbits) or hormonal activity (such as during heat or false pregnancy). Palpation may also trigger vaginal discharge in some cases. Additionally, the veterinarian should check for signs of pain, such as the rabbit tensing its abdomen or showing a pain response during examination.

X-ray:
On an X-ray, an enlarged uterus can be visible, unlike the uterus of a young, healthy rabbit, which is usually not detectable. The enlargement may be uniform or irregular. However, other potential causes of uterine visibility include obesity, age-related fatty deposits, or hormonal activity (e.g., during heat). Uterine tumors often show signs of calcification in X-ray images.

Ultrasound:
Ultrasound provides the most accurate diagnosis, provided the veterinarian has sufficient experience with the procedure. This method allows for the visualization of uterine enlargement, surface abnormalities, and uterine tumors. However, ultrasound cannot reliably differentiate between types of fluids (e.g., blood or water) within the uterus.

Hormonal Imbalances in Rabbits

Estrus (Heat)

Estrus is not a disease but rather a normal physiological process.

Symptoms:

• Posture: The doe may present herself to a buck by lifting her hindquarters while pressing her chest to the ground.
• Vulva Changes: A well-perfused, swollen, and reddish vulva is a typical sign of estrus.
• Behavioral Changes:
  • Restlessness, aggression, tension, and irritability.
  • Marking territory with urine sprays, droppings, and scent from their chin gland.
  • Disturbing bucks and mounting other rabbits or objects.
  • Standing with an erect tail, thumping hind legs, and showing a tense body posture.
  • Occasionally, nest-building behaviors, including plucking their own fur.

Even typically calm rabbits may fight during this period, as does in estrus are often highly irritable. The extent of these behaviors depends on the rabbit’s individual temperament and hormonal state.

Duration:
The duration of estrus varies greatly but typically lasts only a few days.

Hypersexuality and Prolonged Estrus:
Hypersexuality, or an excessive sexual drive, can lead to prolonged estrus. This is more common in indoor rabbits, as they do not experience the natural temperature fluctuations that would normally induce a period of reproductive dormancy, particularly during winter months.

Triggers: What Increases the Likelihood of Estrus?

Estrus occurs as part of the rabbit’s natural reproductive cycle but can be influenced by several factors.

Factors That Promote Estrus:

• Presence of Bucks or Neutered Males: Rabbits in groups with bucks or neutered males are more likely to enter estrus.

• Seasonal Influences: Springtime, increased daylight, and warmer temperatures signal reproductive readiness.

• Social Behaviors: Mounting between rabbits in the group can act as a trigger.

• Lifestyle and Diet: Limited exercise, lack of stimulation, and a rich, nutrient-dense diet mimic conditions that favor reproduction in the wild.

• Group Dynamics: Conflicts within the group and reintroductions (e.g., during bonding) often lead to false pregnancies and estrus.

Stimulation by Humans: It is debated whether petting unspayed females could have a stimulating effect on their estrus cycle.

Factors That Decrease the Likelihood of Estrus:

• Environmental Factors: Winter, cold temperatures, low light exposure, and food scarcity suppress reproductive activity.

• Social Conditions: Rabbits kept alone, in all-female groups, or with limited mounting behaviors are less likely to experience estrus.

• Hierarchy: Dominant rabbits are significantly more likely to experience estrus and reproduce than subordinate ones, as studies have shown.

• Both wild and domestic rabbits are influenced by these factors, which reflect their natural breeding adaptations.

False Pregnancy (Pseudopregnancy)

Symptoms:

• Same symptoms as estrus (heat).

• Additional signs include milk production (lactation) with swollen mammary glands.

False pregnancy is typically triggered by a failed mating, petting, or other manual stimulation.

It can be difficult for non-experts to differentiate false pregnancy from a normal pregnancy. However, if there has been no contact with a fertile buck, pregnancy is not possible.

Treatment: What to Do If Your Rabbit is Experiencing False Pregnancy or Estrus?

First, it’s important to understand that hormonal fluctuations in rabbits are completely normal. Rabbits are highly reproductive, active animals that go into heat multiple times a year and can also occasionally experience false pregnancies.

However, certain factors can increase the likelihood of these conditions. Stress, as well as factors like spring weather, sunlight, and heat, can make these hormonal behaviors more frequent. Therefore, it’s important to observe if your rabbit is under significant stress if it experiences frequent heat cycles.

Ways to Mitigate Hormonal Behavior:

• Enrichment: Providing plenty of opportunities for digging and exploring, such as piles of branches or leaves, can help the rabbit „vent“ its energy.
• Outdoor Housing: Outdoor housing allows the rabbit to experience natural daylight and temperature fluctuations, which can regulate its hormonal cycles.
• Balanced Diet: Avoid overfeeding or providing too nutrient-rich food, as this can influence hormonal behavior.

By offering ample space and enrichment to tire the rabbit out, it helps restore a sense of balance. Rabbits are naturally active and require space to move; confinement in small cages, pens, or enclosures is entirely unsuitable for them.

Please inform yourself about the proper care and housing for rabbits:

Outdoor Housing
Indoor Housing
Balcony Housing

Make sure that shelters have at least two entrances so that rabbits can avoid each other and escape if they are not getting along due to hormonal changes.

Change their setup daily to keep them engaged in exploring.

If a rabbit shows signs that could indicate a uterine condition, it can be checked through an ultrasound (+ possibly a blood test). Highly hormonally active rabbits should definitely be thoroughly examined (not just palpated!).

We’ve had good experiences with Hormeel by Heel when administered over several weeks (1-3 times a day on a treat, allowing it to dry). We give it to rabbits whose hormonal activity doesn’t subside and remains elevated for long periods (prolonged heat).

RodiCare Pregno has also provided relief for some rabbits.

From classical homeopathy, remedies like Pulsatilla and Ignatia may be considered. However, the right remedy for each rabbit should be chosen by a qualified animal homeopath, depending on the individual case.

Soothing herbs such as lavender, valerian, and lemon balm are often helpful in their diet to calm them.

Hormonal medications, such as Galastop, are completely unsuitable. They lead to a high rate of uterine diseases and are therefore not recommended for rabbits.

For more information on treating heat and false pregnancies…

Endometrial Hyperplasia

A common increase in the volume of the uterine lining.

Cause:
Endometrial hyperplasia occurs due to stronger hormonal influence, particularly estrogen and progesterone, which cause thickening of the uterine wall. Rabbits that display excessive sexual behavior, frequent estrus (heat), false pregnancies, aggression, and dominance behavior are especially prone to this condition.

Forms:

• Pure thickening of the uterine lining
• Development of uterine cysts (initially small, but potentially growing over time)
• Blood or blood clots in the urine

Symptoms:

• Often asymptomatic (usually discovered incidentally during vaccinations or X-rays)
• Occasionally excessive sexual behavior, frequent heat cycles, and false pregnancies due to hormone production from cysts
• Possible pain, leading to recurrent loss of appetite and withdrawn behavior (often mistaken for digestive issues)
• Digestive disturbances caused by extremely large cysts or very fatty uterine lining, which can displace the intestines
• Affected does typically have a very swollen abdomen, but a prominent, thin spine (weight loss)
• Recurring bleeding from the vagina or in the urine, often without general health deterioration (due to ruptures in blood vessels). In cases of extreme bleeding, anemia can occur, and it may even become life-threatening.

Treatment:

If the rabbit shows no symptoms and the condition is only discovered incidentally, no immediate treatment may be necessary.

Pure uterine enlargement is not inherently problematic and is considered normal in older rabbits. It only becomes an issue if it presses on the intestines, leading to symptoms. In overweight rabbits without cysts, a gentle diet may help alleviate symptoms.

However, if cysts are contributing to the uterine enlargement, it’s important to recognize that the rabbit could be under constant hormonal influence, which could potentially lead to uterine tumors or hydro-/mucometra.

If the rabbit is symptomatic due to endometrial hyperplasia (e.g., anemia, pain, digestive issues, lethargy, significant blood loss—see above), a complete spay (ovariohysterectomy) should be performed. This procedure is essential for the rabbit’s health and well-being.

Under no circumstances should the cycle be suppressed using a progestogen (e.g., Galastop)! In rabbits, this treatment significantly increases the risk of developing uterine tumors and pyometra. It should only be considered if a spay (ovariohysterectomy) is performed immediately afterward.

Uterine Tumor

Uterine cancer, often caused by hormonal influences.

Typically, these tumors are adenocarcinomas, though leiomyosarcomas can also occur. Adenocarcinomas tend to metastasize to the lungs later, while leiomyosarcomas spread early. Uterine tumors can also contain cysts. They most commonly develop due to strong, prolonged hormonal influence, and may also be accompanied by a condition known as hämometra (blood-filled uterus). Does over 5 years of age are particularly prone to these tumors.

Symptoms:
The symptoms are similar to those of endometrial hyperplasia with concurrent hämometra, as uterine tumors, like hyperplasia, can press on the digestive system due to their enlargement. Additionally, the uterus may contain cysts.

Other signs include:

A bloated abdomen despite a prominent, bony spine (weight loss).
Weakness or recurring episodes of weakness. In some cases, there may be pronounced weakness in the hind limbs.
If the tumor has already metastasized, breathing difficulties may occur.

Treatment:
Before proceeding with a complete spay (ovariohysterectomy), it is crucial to rule out lung metastasis via X-rays in two planes. If the tumor has spread to the lungs, the prognosis is very poor, and treatment would focus on palliative care with pain relief.
If metastasis has not occurred, a prompt ovariohysterectomy is recommended, and the prognosis is generally good.

Hämometra

Blood accumulation in the uterus.

This condition can result from uterine cysts or a uterine tumor, leading to bleeding due to vessel rupture. If the cervix remains closed, the blood accumulation often goes unnoticed inside the rabbit. However, if the cervix opens, vaginal discharge occurs, often mixed with urine.

Symptoms:

• Withdrawn behavior (lethargy) due to blood loss
• Recurrent bleeding from the vagina (often visible in the urine) or severe bleeding, which can be life-threatening
• Anemia in the blood test (due to blood loss)

Treatment:

In cases of heavy bleeding, an immediate total spay (ovariohysterectomy) is required. In other cases, it is advisable to stabilize the rabbit first (symptomatic treatment, infusions, etc.) and then proceed with the spay. This approach helps reduce anesthesia risks.

Hydro-/Mukometra

Water- or mucus-filled uterus.

Prolonged hormonal influence (e.g., cysts), tumors that obstruct fluid drainage, or malformations of the reproductive organs (in young does) can cause a large accumulation of watery or mucous secretions, especially when the cervix is closed. This often results in an extremely enlarged uterus.

Symptoms:

If the mucus drains, it may be noticed by the rabbit owner, but the rabbit is usually otherwise healthy and active.
When fluid builds up, rabbits become increasingly bloated, yet they have a thin spine (weight loss). They often appear lethargic, eat small amounts (due to the uterus compressing the stomach), and commonly experience digestive disturbances (e.g., colic and constipation).

Treatment:
A rapid ovariohysterectomy (spay) is recommended, and the abdominal cavity should be filled with full electrolyte solution to compensate for the volume loss. Additionally, generous infusions should be given before and after the surgery. The prognosis is generally favorable after treatment.

Purulent Uterine Inflammation (Pyometra)

Life-threatening uterine infection.

Pyometra is an acute condition that leads to severe illness in the rabbit and requires immediate treatment to prevent death. It is caused by ascending infections (from the vagina) and is very rare. However, the use of progestins (e.g., Galastop) can significantly increase the likelihood of this condition. Rabbits carrying the snuffles bacteria are also more frequently affected.

There are two types of pyometra:

• Open pyometra: Pus is discharged through the vagina.
• Closed pyometra: The cervix is closed, and pus accumulates within the uterus.

Symptoms:

• Disturbed general condition, lethargy, withdrawal
• Vaginal discharge (sometimes mixed with urine)
• Refusal to eat
• Pain
• Weight loss (spine palpable) despite a bloated abdomen

Treatment:

Immediate spaying (ovariohysterectomy) is necessary to save the rabbit. Prior to surgery, the rabbit’s circulation may need to be stabilized with infusions and antibiotics. Post-surgery, the rabbit will require continued infusions to ensure recovery.

Sources include, among others:

Ewringmann, A. (2016): Leitsymptome beim Kaninchen: diagnostischer Leitfaden und Therapie. Georg Thieme Verlag.

Fuchs, S., Kiefer, I., Niesterok, C., & Eberhardt, F. (2013): Ultraschall bei Kaninchen und Meerschweinchen–Häufigste pathologische Befunde des Geschlechtsapparats. kleintier konkret, 16(03), 23-28.

Glöckner, B. (2009): Uteruserkrankungen des Kaninchens–Sicher diagnostiziert, erfolgreich therapiert. kleintier konkret, 12(04), 23-27.

Heckermann H. (2008): Beitrag zur Art und Häufigkeit von Uterusveränderungen beim Kaninchen – Retrospektive Studie. Wien: Institut für Pathologie und Gerichtliche Veterinärmedizin der Veterinärmedizinischen Universität Wien

Hofheinz, A. R. (2007): Sonographische Darstellung der männlichen und weiblichen Geschlechtsorgane und der Trächtigkeit beim Kaninchen (Doctoral dissertation, lmu).

Köstlinger, S. (2014): Notfälle beim Kaninchen. kleintier konkret, 17(S 02), 2-7.

Köstlinger, S., & Lübke, C. (2015): Ovariohysterektomie beim Kaninchen. kleintier konkret, 18(S 02), 20-25.

Lübke, V. Christine (2018): Evaluierung von Befunden aus Röntgen und Sonographie weiblich unkastrierter Kaninchen hinsichtlich pathologischer UterusveränderungenEvaluation of radiological and sonographical evidence of intact female rabbits regarding pathological uterine diseases. [https://elib.tiho-hannover.de/rsc/viewer/tiho_derivate_00000017/luebkev_ws18.pdf?page=106, abgerufen am 05.10.19]

Streicher, M., & Hach, V. (2006): Das Uterus-Adenokarzinom des Kaninchens. Kleintierpraxis, 51(6), 309.

Walter, B., Poth, T., Böhmer, E., Braun, J., & Matis, U. (2010): Uterine disorders in 59 rabbits. The Veterinary record, 166(8), 230.