Neoplasia (tumor) is the term given to describe abnormal tissue that can be anywhere in the body. Neoplasia may or may not be cancerous. When discussing gastrointestinal neoplasia, this refers to tumors within the gastrointestinal system, in particular the stomach, intestines and cecum (part of the intestines).

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Rabbits diagnosed with neoplasia in the gastrointestinal tract is not common, but it may be that they are underdiagnosed or not recognized as much as they should be. The most common tumors in rabbits are those in unspayed (entire) female rabbits who often develop uterine adenocarcinomas (malignant tumors in the uterus) and thymomas (benign or malignant tumors in the chest cavity) – both of these are serious and often rapidly fatal. As rabbit medicine continues to advance, we are diagnosing conditions that were previously not seen or able to diagnose and treat.

Tumors are more common in older animals and rabbits are no different. The breed and sex of the rabbit is not a known factor with gastrointestinal neoplasia but is with other tumors.

As with many conditions, the signs that rabbits show are non-specific and can be related to a host of other conditions. Rabbits with gastrointestinal neoplasia may show some of the following signs:

• Lack of or loss of appetite.
• Fewer or no droppings being passed.
• Diarrhea.
• Weight loss.
• Potbellied appearance.
• The spine being more prominent.
• Muscle mass loss.
• Abdominal pain.
• Bruxism (tooth grinding).
• Lack of interest in surroundings/companion.
• Sitting hunched in a corner.

One of the problems is that the signs shown can be due to a variety of possible underlying causes, and your veterinarian will need to eliminate possible conditions, as well as offering supportive treatment. Your veterinarian will likely advise:

• Supportive fluid therapy and assisted feeding.
• Medications to keep the gastrointestinal tract moving (prokinetics).
• Pain relief.
• Bloods.
• Ultrasound.
• X-rays.
• Fecal examination.

As gastrointestinal neoplasia is not common in rabbits your veterinarian is likely to need to refer your rabbit or seek advice from an oncologist. Surgically removing tumors from the GI tract of rabbits is high risk and may not be possible if the tumor is large or in an area whereby it cannot be removed. Chemotherapy and supportive treatment may be possible to help make your rabbit more comfortable but is palliative care and will not cure them.

If the tumor cannot be removed, or if it is malignant and has spread to other areas of the body, then the prognosis is extremely poor, and euthanasia is often the kindest option. If the tumor can be removed and it has not spread, then this may be curative, although surgery and recovery will be high risk. Palliative care may give the rabbit more time, from days, weeks or a couple of months, but it is not likely to increase the lifespan by more than that.