by Jill Mullen

Created on: October 30, 2008

It is always a nasty surprise to find a lump of any sort on your pet. You may discover it whilst grooming or stroking your pet, and for peace of mind you should arrange for your vet to examine the lump. The good news is that a lot of our pet's lumps and bumps are very benign, and many of them will be Lipomas.
Lipomas form from abnormal adipose cells, fat cells that have a greater affinity for spare fat calories than normal adipose cells. They form a lump as the abnormal cells aggregate together. Lipomas may form almost anywhere on the body, but are most common on the trunk. They may lie just beneath the skin and feel soft, rounded and freely mobile. They can form beneath or between superficial muscles of the abdominal wall, thorax and upper limb and here they will be much less mobile trapped by the muscles surrounding them. They will still feel smooth and touching them should be painless. Rarely they form on the lower limb between the small muscles and tendons. Here there is little space for them to form soft rounded swellings and will instead infiltrate the tissues, wrapping around tendons, blood vessels and nerves causing non mobile firm swellings.

Once your vet has examined the lump, most likely they will suggest a biopsy of the swelling. This can often be done without need for even sedation if your pet is cooperative! The small sample of cells will be examined by a pathologist, and the microscopic appearance of the fatty cells will confirm a diagnosis of lipoma.
What happens next depends largely on the location of the lipoma. The most important factor in deciding whether or not to surgically remove the lipoma is its location. In general terms, if it's freely mobile, not too big and not causing problems, leave it alone and wait and see if this changes. If it in a position that may lead to problems if it grows a lot, such as the armpit where it may interfere with movement, remove it if it is growing quickly before it becomes major surgery. If it is infiltrative, such as on the lower limb, get it removed but be warned if all the abnormal fat cells can't be removed it may grow back in the same place. It is a benign growth, it doesn't spread to other organs, but many animals develop multiple lipomas, especially in later life.
So if surgery is not necessary or not necessary yet, what can you do to reduce the chances of needing surgery later?
Remember lipomas form from fat! If there is spare fat available to the body it will preferentially be stored in the lipoma. It follows therefore that keeping a strict check on the diet is the most effective way to control the rate the lipoma grows. Slimming your pet down may initially make the lipoma look bigger... it's not surrounded and padded by normal fat anymore. Use a fat restricted diet to prevent peaks of fat in the blood after eating. Increase calorie burning exercise so that the daily diet provides only what is needed for that day and no excesses that could be turned into fats for storage.
Take the advice of your vet, but in most cases 'Wait and see' will be all you need to do for treatment, reducing the chances of surgery relies on diet control.

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