What are lipomas?
Lipomas are benign (non-cancerous) fatty tumors that commonly develop in middle-aged and older dogs (source 1). They form from fat cells that clump together to create a soft, movable lump under or on top of the skin (source 2). Lipomas most often occur on the torso, upper legs, upper back, and shoulders, but can develop anywhere on the body.
Lipomas are soft, rounded lumps that feel rubbery or spongy, and can range from pea-sized to several inches across. They have defined edges and can usually be moved around under the skin somewhat easily. The skin over a lipoma is usually unaffected and moves freely over the lump.
What causes lipomas in dogs?
The exact cause of lipomas in dogs is unknown. However, there are some potential contributing factors that may influence their development:
Genetics – Certain breeds like Labrador Retrievers, Doberman Pinschers, and Miniature Schnauzers are more prone to developing lipomas, suggesting a possible genetic component. The hereditary nature indicates it may be passed down from parents to offspring.
Obesity – Overweight and obese dogs appear to be at higher risk for lipomas. Excess fat cells may multiply abnormally and form lipomas.
Trauma – Injury to an area, like blunt force trauma, may potentially trigger the formation of a lipoma lump as a response to the trauma. However, this link is considered weak.
Age – Most lipomas surface in middle-aged to older dogs, between the ages of 6-10. The risk seems to increase with age.
While the exact triggers remain unknown, some combination of genetics, fat cells, and age likely contribute. More research is needed on the precise causes and risk factors [1].
At what age do lipomas develop?
Lipomas often develop in middle-aged and older dogs, typically between the ages of 8-10 years. According to a 2018 study published in the Veterinary Ireland Journal, the median age of dogs with lipomas was 10.02 years, compared to 4.18 years for dogs without lipomas. The odds of developing lipomas increased with age, with dogs over 10 years old having 6 times the odds compared to younger dogs [1]. The development of lipomas at a younger age is less common. However, some breeds like Labrador Retrievers may develop their first lipomas between ages 4-6.
[1] https://www.veterinaryirelandjournal.com/small-animal/79-lipoma-in-dogs-how-common-are-they-and-what-breeds-are-affected
Which breeds are prone to lipomas?
Certain breeds of dogs seem to be genetically predisposed to developing lipomas. According to the Veterinary Ireland Journal, breeds with the highest lipoma prevalence include Weimaraners (7.84%), Doberman Pinschers (6.96%), German Pointers (5.23%), Springer Spaniels (5.19%), and Labrador Retrievers (5.08%)
Other breeds prone to lipomas include Cocker Spaniels, Dachshunds, Miniature Schnauzers, Beagles, Keeshonds, and Golden Retrievers, according to the Denver Veterinary Clinic (source). The tendency for lipomas is likely inherited in these breeds.
In general, purebred, middle-aged dogs seem to develop lipomas more often than mixed breeds. Overweight female dogs also tend to develop more lipomas than males.
Where do lipomas occur on dogs?
Lipomas typically develop in areas where there is fatty tissue under the skin, most commonly on a dog’s torso, legs, and armpits. According to VCA Animal Hospitals, lipomas frequently form on the torso, upper legs, upper back, and armpits. However, they can develop anywhere on a dog’s body where there is fatty tissue.
The torso is the most common location for lipomas in dogs. They often occur along the chest, abdomen, and back. Lipomas on the torso are usually soft, movable lumps that grow slowly beneath the skin. Though they may grow large, they tend to be benign fatty masses.
After the torso, the upper legs and armpits are other prime locations for lipomas. Denver Veterinary Clinic notes lipomas between the legs can sometimes cause discomfort or lameness as they enlarge. Those under the armpits may impede limb motion if they become too large. While usually benign, lipomas in these areas may require removal for the dog’s comfort.
Overall, lipomas can develop in any location with sufficient fatty tissue. However, the torso, legs, and armpits are the most common sites. Careful monitoring of any lipomas in sensitive body areas is advised to ensure they do not impact the dog’s mobility or quality of life.
Do lipomas in dogs keep growing?
Lipomas in dogs typically have a slow, continuous growth rate that varies between individual dogs. Most lipomas start out pea-sized and grow slowly over time.
Some lipomas may remain very small, while others can grow to reach several inches in diameter. According to the VCA, while small lipomas often go unnoticed, larger lipomas that grow rapidly “can affect the health of the patient” (source).
The rate and eventual size a lipoma grows to depends on factors like its location on the dog’s body, the breed, and the dog’s age. Lipomas tend to grow faster in middle-aged and older dogs. Certain breeds like Labradors, Dobermans, and Schnauzers are prone to developing larger lipomas.
So in summary – while each lipoma is different, they generally continue growing slowly over a long period. Larger, faster growing lipomas may become a concern and require treatment. Checking new or rapidly growing lumps with a vet is advised.
When should a vet be consulted?
Lipomas are typically benign fatty tumors that do not require any treatment. However, there are some instances when a veterinary visit is warranted:
- The lipoma appears suddenly, grows rapidly, or interferes with your dog’s movement. Dogs that develop lipomas quickly or have fast-growing lumps should be examined to rule out cancerous tumors like liposarcomas, according to the ASPCA
- The lipoma is ulcerated, bleeding, or oozing fluid. This may be a sign of infection or malignancy.
- The lipoma is located in an area like the armpit or groin and presses on blood vessels or nerves. Lipomas in these sensitive regions can cause pain or mobility issues.
- Your dog has multiple lipomas. While not always concerning, some cancers like lymphoma can present with multiple fatty masses.
- Biopsy may be recommended if your vet suspects the lump could be malignant based on its appearance, texture, location or your dog’s health history. A biopsy can differentiate between lipomas and cancers like liposarcomas.
In most scenarios, monitoring lipomas at home is sufficient. But rapid changes in size, shape or symptoms warrant a veterinary examination to diagnose and treat the lipoma appropriately.
Diagnosing lipomas
Diagnosing lipomas in dogs begins with a veterinarian performing a physical exam. The vet will feel and visually inspect the fatty tumor to determine that it has characteristics consistent with a lipoma, such as: a soft, movable lump under the skin covered in normal skin and hair (source). The vet may use a hypodermic needle to extract cells from the lump to get a sample for examination under a microscope. This procedure is called fine needle aspiration and can help confirm that the cells are benign fat cells found in lipomas, rather than something more serious like a malignant tumor (source).
While most lipomas can be diagnosed through physical exam alone, some may require a biopsy where the vet surgically removes a small sample of the tumor for pathological testing. This helps definitively differentiate the mass from potential cancers like liposarcoma. Biopsies are more commonly needed for fast growing lipomas or ones located in deeper tissues (source).
Treatment options
If the lipoma is small and not causing any problems, the vet may recommend just observing it for changes. Often lipomas grow slowly or remain stable for long periods. As long as they are not impairing mobility or growing rapidly, monitoring them is usually sufficient.
However, if the lipoma becomes large, bothersome, or shows concerning changes, surgical removal may be recommended. Surgery is often curative if the entire mass can be removed. The procedure may be minimally invasive if the lipoma is in a location that is easy to access. General anesthesia is usually required.[1] More complex surgeries may be needed if the lipoma is deep, entangled in nerves or blood vessels, or covering a large area. Risks and recovery time increase with larger procedures.
In some cases, it may not be possible to fully remove the lipoma if it is too invasive or entangled with important structures. The vet will weigh risks versus benefits. Alternatives like debulking or liposuction may be considered to partially reduce the size.
Owners should discuss all options with their vet. Factors like the dog’s age, health, mobility, and quality of life will help determine the best course of action for that individual.
Preventing lipomas
While there is no foolproof way to prevent lipomas from developing in dogs, there are some steps owners can take to reduce the risk:
Maintaining a healthy weight and ensuring regular exercise is one of the best ways to help prevent lipomas. Overweight and obese dogs are more prone to developing lipomas, so keeping your dog trim and fit can help. Regular walks, play time, and access to a yard helps dogs stay active and avoid obesity.
Feeding your dog a high quality diet with omega-3 fatty acids may also help. Some research indicates omega fatty acids can help reduce inflammation in the body and may inhibit lipoma development. Choose a diet rich in fish oils and other healthy fats. You can also supplement with fish oil pills or add salmon, sardines, or other oily fish to your dog’s meals.
While not definitively proven, some holistic vets recommend antioxidants to help strengthen the immune system and potentially prevent lipomas. Adding fruits, vegetables, and herbs high in antioxidants like vitamin C and E to your dog’s diet may be beneficial. Always check with your vet before making major diet changes.
While no prevention method is guaranteed, maintaining your dog’s ideal weight, regular exercise, a quality diet, and antioxidants may all work together to reduce the chances of lipomas developing.
