Rabbits can be diagnosed with a variety of lumps. These include lipomas, which are also known as ‘fatty lumps’ or ‘Adipose tumors’.

A free-floating lipoma removed during surgery © David Perpiñán

A lipoma is a lump made out of fat (adipose) tissue. They usually develop in the fat under the skin (subcutaneous fat), usually feel soft to the touch, and are often mobile (movable) to some degree. They tend to be non-painful to the rabbit, but can occasionally ulcerate if they are self-traumatized or get knocked in some way.

Lipomas are more common in middle-aged and older rabbits, but can occur in both males and females of any breed. Both neutered and entire rabbits can be affected.

Lipomas are benign lumps, which means they are not cancerous and therefore not dangerous. They are most commonly located under the skin and can be anywhere on the body. They can also appear within the abdomen and can grow to a significant size.

As with most lumps, your vet will perform a fine needle aspirate (FNA) which involves placing a needle into the lump and extracting some of the cells to be looked at under a microscope. As lipomas are made up from fat cells, they are easy to differentiate from other types of lumps. This process is not painful and for the majority of rabbits this can be performed with them conscious.

Small lipomas which are not causing the rabbit any irritation tend not to be treated, but you and your veterinarian will need to have a discussion about what is best for your rabbit. Lipomas can grow to a significant size, and depending upon the location on the body, may stop the rabbit from grooming, moving normally and grazing and may become ulcerated if they drag on the floor or get caught in anyway. In this instance, your veterinarian is likely to recommend surgical removal.

If your rabbit’s lipoma needs to be surgically removed, this will need to be performed under a general anesthetic. Your veterinarian will be able to explain and discuss the procedure with you. If the lipoma is very large or if it is on an area of the body, such as a leg, where there is not as much loose skin to close the wound, it may not be possible to fully remove all the lipoma, but a procedure known as ‘debulking’, whereby as much of it is removed as possible to reduce the size, will be performed. If it is not possible to fully close the surgical wound, then this will be closed as much as possible and the rest left to heal by secondary intention. Your veterinarian will discuss the care your rabbit requires after the surgery.

Sometimes the lipoma may regrow in the same location, but it is more likely that others will grow in different locations. Some individual animals, including rabbits, are more prone to lipomas and there is nothing you can do to prevent them.