What If A Lipoma Lump Appeared Overnight On A Dog?

What is a Lipoma?

A lipoma is a benign fatty tumor that is common in older dogs. Lipomas are soft, movable lumps that form under the skin and consist of fatty tissue. According to VCA Animal Hospitals, a lipoma is “a term to describe a very common benign tumor of fat seen in middle-aged to older animals.”

Lipomas are typically slow-growing, noncancerous masses that develop between the skin and muscle layer. They are usually soft to the touch and range in size from a pea to a few inches across. Lipomas feel doughy or rubbery when gently manipulated with the fingers. While they can develop anywhere on the body, lipomas commonly occur on the torso, upper legs, and shoulders.

On examination, lipomas are soft, fluid-filled sacs that are often surrounded by a thin capsule and can sometimes have a stalk or stem attached. They are freely mobile under the skin when manipulated. Owners frequently describe lipomas as “fatty lumps” or “rubbery bumps” when first detecting them on their dog.

Causes of Lipomas

The exact cause of lipomas is unknown, but they may have a hereditary component. Certain breeds, such as Labradors, Dobermans, and Schnauzers seem predisposed to developing lipomas. This suggests there may be a genetic link. However, the cause is likely multifactorial – involving both hereditary and environmental factors.

Lipomas form when fat cells multiply and cluster together, forming a lump or mass under the skin. What triggers these fat cells to start multiplying is unclear. Trauma or injury to an area may potentially trigger the development of a lipoma lump as the body tries to heal. However, many lipomas also develop spontaneously with no known trigger.

Overall, the root cause remains elusive. More research is needed to determine the precise factors leading to lipoma formation in dogs.

Appearance of Overnight Lipomas

While it’s possible for lipomas to grow quickly, it is very rare for one to truly appear overnight. Lipomas are fatty tumors that tend to develop gradually over weeks or months. However, some may grow at a faster rate than others.

In some cases, a lipoma may seem to show up suddenly or overnight if it was previously small and went unnoticed by the owner. As the lipoma enlarges, it eventually becomes visible and palpable under the skin. An owner may think it appeared overnight when in reality it had been slowly growing for some time.

According to VCA Animal Hospitals, “Every lipoma is different; some may grow rapidly and some may take years to grow large enough to be of concern.” (https://vcahospitals.com/know-your-pet/adipose-lipoma-tumors)

While lipomas can enlarge quickly over weeks or months, it would be extremely uncommon for one to literally develop overnight. Any rapidly growing mass should be evaluated by a veterinarian to determine if it is a simple lipoma or another type of lump.

Diagnosing a Lipoma

If your dog develops a new lump overnight, it’s important to have your veterinarian examine it as soon as possible. Your vet will visually inspect and palpate the lump to determine its characteristics. Lipomas typically feel soft and movable under the skin. Your vet may use a hypodermic needle to aspirate cells from the lump for cytological analysis. Cytology involves examining the cells under a microscope to determine if they are fat cells, which is diagnostic for a lipoma.

According to VCA Animal Hospitals, “Typically, these types of tumors can be diagnosed by fine needle aspiration (FNA). FNA involves taking a small needle with a syringe and suctioning a sample of the lump for examination under the microscope.” https://vcahospitals.com/know-your-pet/adipose-lipoma-tumors

PetMD explains, “It is important to have an accurate diagnosis and to know that the mass is indeed a lipoma, but at this point, your veterinarian will likely perform a fine needle aspiration.” https://www.petmd.com/dog/conditions/skin/c_multi_lipoma

Treatment Options

Lipomas are usually benign, slow-growing tumors that do not require treatment in most dogs. Small lipomas that are not causing discomfort can simply be monitored at home. According to VCA Animal Hospitals, “The single most effective treatment for lipomas is surgical removal. It is best to remove these masses when they are small; the surgery is usually less invasive at this stage.”

For some lipomas, vets may recommend steroid injections to shrink the size of the lump. Steroids like dexamethasone or prednisone can help reduce inflammation and discomfort. However, this is usually a temporary treatment option and the lipoma may regrow over time.

Surgical removal is the best treatment option for lipomas that are large, growing quickly, or impacting mobility and normal function. Surgery successfully removes the entire lipoma and offers the best chance of preventing regrowth. According to WebMD, “The earlier a lipoma is removed, the lower the chance of recurrence.”

Post-surgery, owners will need to restrict activity to allow proper healing and keep the incision site clean and dry. Pain medication may be prescribed for a few days after surgery as well. Prognosis after surgical removal is excellent, with most dogs making a full recovery.

Home Care

If your dog has a lipoma that is small and not bothering them, home care may be the best option. Here are some tips for monitoring and caring for a lipoma at home:

Monitor the lipoma for any changes. Check the size, shape, color, and texture regularly. A fast-growing lump can be a sign of a more serious issue like cancer, so keeping an eye on it is important. Contact your vet if you notice significant or sudden changes.

Keep the area around the lipoma clean. Gently wash the area with a mild soap and pat dry. This helps prevent skin infections or irritation. Avoid using harsh cleaners or scrubbing aggressively.

Gently massage the lump daily. This will allow you to feel for any new lumps developing under the skin and detect changes in existing ones. If the lump seems painful, discontinue massaging and contact your vet.

According to one source, topically applying neem oil to the lump twice per day may help shrink lipomas naturally. However, consult your vet before using any home remedies [1].


There is no known way to definitively prevent lipomas from developing in dogs. However, there are some steps owners can take that may help reduce the chances of lipomas forming:

Maintain an ideal body weight. Overweight and obese dogs are more prone to developing fatty lipomas. Keeping your dog at a healthy weight can help prevent excess fat buildup under the skin where lipomas can form. Regular weighing, measuring food portions, and increasing exercise can help maintain lean body mass.[1][2]

Provide excellent nutrition. Feeding your dog a high quality diet with appropriate levels of fat, protein, and carbohydrates can help prevent obesity and reduce fat accumulation. Avoid excess treats and table scraps.

While there’s no definitive way to prevent lipomas, focusing on keeping your dog at a healthy weight and feeding a nutritious diet may help reduce the chances of them developing.


The prognosis for dogs after the diagnosis of a lipoma is generally excellent. Lipomas are benign fatty masses that are not life-threatening (VCA Animal Hospitals). The vast majority of lipomas do not become cancerous or malignant. One study found that only 0.3% of canine lipomas underwent malignant transformation into liposarcoma tumors (PetMD). So there is a very low chance of a lipoma becoming cancerous in dogs.

Since lipomas grow slowly and are not harmful in most cases, the prognosis is good as long as the lipoma does not impair mobility or quality of life. With surgical removal, dogs generally recover very well. Most lipomas will not regrow after surgical removal. Overall, lipomas are not considered life-threatening and the prognosis is excellent, especially if treated early before the lipoma enlarges.

When to See the Vet

In most cases, lipomas in dogs are benign and do not require removal. However, there are some instances when you should take your dog to the vet if a new lipoma appears or an existing one changes:

If the lump grows rapidly over a short period of time, such as doubling in size in just a few weeks, it’s important to get it checked by a vet. Rapid growth may be a sign of a more serious condition like cancer, so a biopsy is recommended (Source).

You should also see your vet if the lipoma interferes with your dog’s movement or mobility. Lipomas that develop in areas like the legs, armpits, or neck can impede motion or cause discomfort when rubbed (Source). Surgical removal may be required.

Finally, any signs of infection around the lipoma lump warrant an immediate vet visit. Redness, heat, discharge or a foul odor indicate infection that needs treatment with antibiotics or drainage (Source). An infected lipoma can quickly become an abscess.


Lipomas are generally harmless fatty tumors that commonly develop in older dogs. While they typically grow slowly over time, occasionally a lipoma lump may seem to appear overnight. This can be alarming for dog owners, but try not to panic. Monitor the lump for any changes in size, shape, color, or consistency and let your vet examine it to determine if it is a lipoma or another type of growth.

Your vet can perform a needle aspiration or biopsy to diagnose a lipoma. Most often, no treatment is necessary beyond monitoring the lump. But if the lipoma is large, growing rapidly, interfering with mobility, or irritating the dog, there are options like steroid injections to shrink it or surgical removal. With appropriate care, most dogs live normal lives with lipomas.

If a new lump appears suddenly overnight on your dog, have your veterinarian assess it as soon as possible. They can diagnose if it is a lipoma or something more serious. With the right diagnosis and treatment if needed, lipomas generally have an excellent prognosis.

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