It can be easy to feel your heart sink when you find a lump on your furry friend. However, the most common cause of lumps and bumps on dogs are fatty lumps or lipomas, which are benign and non-painful types of tumours.
Being benign, a lipoma isn’t going to spread and they aren’t going to put your dog’s life at risk. And because they’re non-painful, they don’t pose much of a problem to your pooch other than looking a little unsightly.
We’ve created this guide on lipoma in dogs to help you to understand what these tumours are, the types of lipoma out there, what impact they have on your dog, and what treatment they might require.
A lipoma, or “simple lipoma”, is a kind of subcutaneous tumour. In other words, it’s a fleshy lump that grows under your dog’s skin.
They’re relatively common and they’re the second most common tumour found in dogs in the UK.
Lipoma is often referred to as “fatty lumps” since that’s basically what they are. A tumour is simply a fleshy lump created by a group of cells multiplying abnormally, and a lipoma is caused when the fat cells under the skin divide and multiply out of control until they form a visible lump of fatty tissue.
Although the word “tumour” can seem scary and immediately make you think of cancer, but don’t be alarmed.
Lipoma is a benign tumour, meaning they are not cancerous and don’t pose a danger to your dog’s health or a risk to their life.
In fact, lipomas are harmless and the only problem they usually pose is purely cosmetic because they cause a visible lump on your dog.
The only time a lipoma might be a problem and require removal is if it has grown in an awkward place that causes your dog discomfort or impacts their daily activities. For example, a lump on their leg might affect your dog’s mobility.
Most lipomas are small and semi-spherical in shape. However, as these tumours grow they can become much larger and rounder. In some cases, they can reach huge sizes, including the size of tennis balls, or almost the size of a dog’s head.
Lipoma is a kind of harmless or benign tumour growing in the fat cells (adipose) in your dog’s body.
However, there is a malignant (cancerous) tumour that can grow in the fat cells called liposarcoma. This is much rarer than lipoma but they can look and feel very similar, which is why your vet must examine your dog and conduct a few tests to check whether their tumour is benign or malignant.
It’s extremely rare, but sometimes lipoma can develop into a liposarcoma, which is why you should always get lumps checked by a vet and monitor them for any changes.
Finally, there is another rare kind of lipoma called infiltrative lipoma.
Like lipoma, an infiltrative lipoma is another kind of benign tumour that grows in the fat cells under your dog’s skin. Like lipoma, it does not spread to other areas of the body and it’s not considered cancerous.
However, unlike simple lipomas, an infiltrative lipoma can invade or “infiltrate” other tissues near where the tumour originated. It may affect your dog’s nearby muscles, connective tissue, nerves, and bone.
Because infiltrative lipoma grows into surrounding tissues it can cause pressure pain or dysfunction in the muscles around them. They’re also much more difficult to remove as they penetrate other tissues, and sometimes surgical removal simply isn’t possible.
Although they can sometimes be surgically removed, infiltrative lipoma is more likely to reoccur and grow back after removal compared to lipoma. Luckily, infiltrative lipomas are much, much rarer than lipoma in dogs.
Although lipomas are a kind of tumour, they are not cancerous or malignant and don’t pose a risk to your dog’s health. Usually, a lipoma will not invade other tissues and it cannot spread to other areas of the body.
Liposarcoma on the other hand is cancerous, and this is also a kind of tumour (lump) that grows in your dog’s fat cells under their skin.
No, a lipoma is not a danger to your dog’s life. Lipoma is a benign tumour and more often than not the only problem they pose to your dog is completely cosmetic.
Sometimes a lump can grow in an awkward place. In cases where a lipoma has grown in a place that causes your pooch discomfort or affects their daily activities, then it may need to be surgically removed.
Even a similar cancerous tumour, liposarcoma, isn’t always life-threatening. It can often be successfully treated with surgery, and many dogs will survive.
Lipoma in dogs, like any other tumour, is caused by the natural lifecycle of cells being disturbed. Instead of cells dying to be replaced by new, healthy cells, the affected cells simply continue to divide and multiply, causing a cluster of cells that pack together and form a lump of tissue. In the case of lipoma, this is a lump of fat tissue.
However, the reasons why this cycle is disturbed and why tumours form are complicated and multifactorial. Some of the reasons this lifecycle is out of balance are due to ageing, illness, infection, or hormones. Environmental factors and your dog’s genetics can also play a part in their risk of lipoma and tumours.
Simply put, it’s near impossible to know exactly why your dog has developed lipoma, and it’s usually a combination of the factors listed above.
Lipomas can develop in any dog of any age, breed, size, or gender. However, they’re much more common in middle-aged and elderly dogs. Dogs aged 9-12 years or older are 17.52x more likely to develop lipoma compared to dogs aged 3-6 years old.
Some health conditions can also make your dog more likely to develop a lipoma. Overweight and obese dogs are almost 2x more likely to develop lipoma compared to dogs of normal weight. Chunky dogs also tend to develop multiple lumps and larger growths.
Some hormonal conditions, including hypothyroidism, can also increase a dog’s risk of lipoma.
Additionally, certain breeds of dogs are more at risk of lipoma compared to others. Some of the dogs predisposed to lipoma are:
There is debate whether there is any breed disposition towards the rarer and cancerous tumour liposarcoma. Many believe no breeds are more likely to develop liposarcoma than others, but some say that the dog breeds prone to lipoma also have a slightly higher risk of liposarcoma.
It’s basically impossible to prevent lipoma in dogs simply because there is no single clear cause for them.
The best you can do is to protect your dog’s overall health by providing a complete diet and regular exercise. This will also help to keep your dog at a healthy weight.
Overweight and obese dogs are more likely to develop multiple lipomas and the tumours that develop on overweight dogs are usually much larger too because there is more fat in their body leading to more fat stored in the lipoma. Keeping your dog a healthy weight can reduce the size of lipomas, making them more manageable and less likely to become uncomfortable or a hindrance to your dog.
Providing preventative care, including vaccinations, can also help to prevent any infections and illnesses that could trigger disturbances in the cell lifecycle that can cause tumours like a lipoma.
However, lipoma and fatty lumps are also seen as a normal part of ageing. You can’t turn back time, so you could find the odd lump or bump developing as your dog gets grey around the muzzle.
Just remember that whenever your notice a new lump, or think that a lump has changed in some way, you must get your vet to check it and make sure it’s not a malignant and harmful tumour.
The signs and symptoms of lipoma in dogs are simply a lump or bump developing under their skin. Usually, these lumps are somewhat soft and can move around a bit, although lipoma in dogs can vary in texture and whether or not they move.
Even though lipoma is the most common cause of lumps under the skin, it’s impossible to tell if it’s a relatively harmless lipoma or something more sinister without a medical examination.
Veterinary examination is vital because if you’re ever in the unlucky scenario where your dog has developed cancer and not lipoma, then early diagnosis and treatment will improve their chances of recovery.
Lipomas have a distinct feel and texture because they are relatively mobile fatty lumps. Usually, a vet will be confident enough to make a diagnosis of lipoma based on a physical examination of the lump and a discussion of your dog’s symptoms, risk factors, and family history.
Your vet might also choose to perform a fine needle aspiration to analyse the cells that are making up the tumour, just to check it’s definitely benign and harmless. This will involve inserting a very thin needle into the lump and using it to syringe out a few of the cells from inside the tumour. Your vet can examine these cells to see if it’s a lipoma or something else.
They could also take a biopsy for the same purpose, which requires cutting out a tissue sample from the lump in order to examine the cells and identify whether it is a benign lipoma or cancer.
More often than not, no treatment is required for lipoma in dogs. Because the tumour is benign, painless, and slow-growing, there’s usually no reason to risk putting your dog under anaesthetic or through treatments like chemotherapy to get rid of the tumour because there will be no obvious improvement to their health or wellbeing.
However, some lipomas require surgical removal if they’re extremely large, uncomfortable, or interfere with movement or other daily activities. Sometimes a lipoma may be removed for cosmetic reasons. Lipomas growing on the neck, chest, leg, or armpit are often removed.
Your dog will usually have day surgery to remove the tumour and a little bit of skin around it, then their skin will be stitched back together. This may form a small scar called an “ear” which can sometimes feel like a smaller lump and might cause a swirl in your dog’s fur.
After surgery, your pooch will need to wear an E-collar or a protective medical shirt to stop them from licking or chewing their wound. Depending on where the lipoma was removed, they might also need to be on crate rest or limited exercise to give their body time to heal.
Once your dog’s lipoma has been removed, they usually only need a check-up with the vet a week or so later to check that their wound is healing and without infection. They might also need to have some stitches removed.
Meanwhile, if your dog has had infiltrative lipoma they may require surgery to remove it (if surgery is possible). Some dogs may be provided with radiation therapy to remove any remaining tumour cells or to try and remove tumours that cannot be removed through traditional surgery.
Usually, your vet will advise that you either leave the fatty lump and simply monitor it or surgically remove it.
However, many dogs will see their lipomas shrink or simply vanish if they lose weight.
If appropriate, and with the guidance of your vet, you can start a weight loss regime for your dog. This is usually a simple switch to a healthy diet with properly measured meal portions, alongside providing additional exercise for your pooch.
Weight loss will help to reduce the levels of fat in your dog’s body which also reduces fatty lumps. Maintaining a healthy weight will also benefit your dog’s overall health, it can improve conditions like arthritis and hip dysplasia, and it will help your dog to lead a much longer life.
There are also a few “home remedies” for lipoma out there, including green tea and the amino acid L-carnitine. These both work by supposedly increasing your dog’s metabolism, leading to the use of fat stores as energy and a reduction in fat.
A study on budgies suggested supplementary l-carnitine and a controlled diet reduced lipomas. However, the variables in diet alone were significant and the reduction in fat and lipoma could have been caused by the controlled, lower-fat diet rather than the supplementary l-carnitine.
You can ask your vet if it’s safe and appropriate to use supplements like these to help reduce your dog’s lipoma, but in most cases, it’s simply easier and cheaper to just feed your dog a correctly-portioned diet and provide more exercise so that they lose weight in a controlled, healthy manner.
If you’ve found a lump on your dog, you might be worried about the prognosis. However, a lipoma is a common cause of lumps and it’s considered harmless.
Because lipoma in dogs is benign, painless, and doesn’t spread, it typically won’t pose any risk to your dog’s health or stop them from living a long and happy life.
Some lipomas may require surgical removal, but lipoma in dogs often requires no treatment and won’t impact your dog’s health or wellbeing in any way.
However, it’s vital that you always get any new lumps checked by a vet just to make sure it isn’t cancer. You should also get your dog’s lumps checked any time you notice any changes such as growth, changes of colour, or discharge leaking from them.
It’s a good idea to get your dog’s lumps checked regularly, even if they were diagnosed as lipoma, to make sure they’re still benign and not hindering your dog’s daily activities.
You can take your dog in for a routine check-up or get your vet to check these lumps whenever your pooch goes in for a physical exam, like whenever they go in for their booster vaccinations.
Written by: Dr Andrew Miller MRCVS
Andy graduated from Bristol University in 2010 and sees nutrition as a foundation for our pet's wellbeing and takes a common-sense approach. We are what we eat, and it shouldn't be any different for our pets.