Tumours in Rabbits: Types, Risk and Treatment

In this guide

Tumours are more common in pet rabbits than many owners expect, and the single biggest risk factor by far is remaining unspayed or unneutered. This is one of the clearest cases in rabbit care where a preventive procedure has an outsized effect on lifelong health.

Uterine cancer in unspayed females

Uterine adenocarcinoma is the most frequently diagnosed cancer in pet rabbits, affecting a very large proportion of unspayed females by five years of age, with risk climbing steeply with age. Early signs can be subtle or absent, though blood in the urine, a swollen abdomen, or reduced fertility in a breeding doe can be clues. Spaying before this cancer develops removes the risk almost entirely, and even after diagnosis, spaying is often the primary treatment if the cancer has not yet spread.

Mammary tumours

Also mostly seen in unspayed females, sometimes alongside uterine cancer. A lump or thickening around the mammary tissue is the main sign, and surgical removal is the standard treatment, with better outcomes the earlier it is caught.

Testicular tumours in males

Less common than reproductive cancers in females, but they do occur in unneutered male rabbits, usually presenting as a firm swelling in one or both testicles. Castration is both the treatment and, if done early, the prevention.

Lymphoma and other cancers

Lymphoma can affect rabbits of any age, including younger ones, and can involve the lymph nodes, gut, spleen or liver. Signs are often vague, including weight loss, lethargy or a swollen abdomen, which makes it harder to catch early than reproductive cancers.

Why spaying and neutering matters so much here

Given how heavily these cancers concentrate in unspayed and unneutered rabbits, spaying females and neutering males remains the single most effective preventive step available, alongside routine vet checks that include gentle abdominal palpation to catch anything unusual early.

Not every lump is a tumour

Abscesses, which are fairly common in rabbits and often linked to dental disease or a wound, can feel similar to a tumour from the outside but are a different problem requiring different treatment, usually drainage and antibiotics rather than surgery aimed at cancer. A vet visit with imaging or a needle sample is the only reliable way to tell the two apart, so it is worth avoiding assumptions either way based on feel alone.

A simple home check

Running your hands gently over your rabbit's body every couple of weeks, including the abdomen, mammary area, and testicles in unneutered males, helps you notice any new lump early. This takes only a minute or two during a normal grooming or handling session and is one of the easiest habits to build into regular care.

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