What are Lipomas?
Lipomas are benign (noncancerous) fatty tumors that commonly develop in middle-aged to older dogs, usually ages 6 years and older (WebMD, 2022). They form as rubbery lumps under the skin and can occur anywhere on a dog’s body, but are most often found on the torso, upper legs, upper back, and shoulders. Lipomas are encapsulated masses of fat cells that gather below the skin, creating a soft, movable lump. They range in size from a marbles to a few inches across, and have a doughy or rubbery texture. The overlying skin generally retains its normal appearance and hair growth.
Lipomas are typically slow-growing, solitary lumps, but some dogs may develop multiple lipomas over time. They are not painful or itchy in most cases, and do not usually impair a dog’s mobility or quality of life unless they become exceptionally large or restrict joint movement (VCA Hospitals, 2022). Overall, lipomas are benign fatty deposits that only rarely present complications.
Causes and Risk Factors
While the exact cause of lipomas in dogs is unknown, some possible risk factors have been identified:
Genetics may play a role, as certain breeds like Dobermans, Labrador Retrievers, and Miniature Schnauzers seem predisposed to developing lipomas. However, no specific genetic mutation has been definitively linked to lipomas in dogs [1].
Obesity and older age are associated with an increased risk of lipomas. Overweight dogs tend to develop lipomas at a younger age compared to dogs fed a lean diet [2].
While these factors may raise the likelihood of lipomas, no definitive cause has been identified. Lipomas can develop in dogs of any breed, age, or body condition.
Diagnosing Lipomas
Veterinarians use several methods to diagnose lipomas in dogs. The first step is a physical exam and palpation of the lump. Lipomas have a very distinct feel – they move freely under the skin and feel soft and squishy.1
It’s important for vets to distinguish lipomas from other types of lumps and growths. Some characteristics that indicate a lipoma include:
- Located just under the skin
- Easily movable and soft to the touch
- Rounded shape
- Covered by normal skin
If the lump has any characteristics that seem suspicious or unusual, the vet may recommend a biopsy to identify if it is cancerous. This is especially true for fast-growing lumps. 2
Treatment Options
There are several options for treating lipomas in dogs, depending on the size and location of the growth:
Observation – For small lipomas that are not bothering the dog, vets may recommend just observing the lump periodically to see if it grows. Lipomas often grow slowly or not at all, so this conservative approach may be appropriate if the lipoma is not interfering with the dog’s movement or quality of life.
Surgical Removal – Surgical removal is considered the most effective treatment option for lipomas in dogs. VCA Animal Hospitals notes it’s best to remove lipomas when they are small, as the surgery is less invasive. The vet will surgically excise the entire lipoma. The procedure is relatively simple with minimal recovery time.
Steroid Injections – Some vets may inject a steroid directly into the lipoma to try to shrink it. PetCure Oncology states that injectable steroids may reduce inflammation and shrink the tumor temporarily. However, the lipoma often regrows after some time. Multiple injections may be required.
Steroid Injections
Steroid injections can be an effective treatment option for shrinking lipomas in dogs. Steroids like triamcinolone work by reducing inflammation and suppressing the immune system [1]. When injected directly into the lipoma, the steroid helps shrink the fatty tumor by:
- Reducing the inflammatory response
- Restricting the blood supply to the lipoma
- Slowing or preventing the growth of fat cells
The typical dosage is 1-2 mg/kg, administered every 2-3 weeks. The frequency and duration depends on the size of the lipoma. Smaller lipomas may only require 1-2 injections, while larger ones may need 3 or more over 2-3 months [2].
Potential side effects include:
- Pain or swelling at the injection site
- Skin pigment changes
- Infection
- Recurrence of the lipoma
Careful monitoring under veterinary supervision is important when pursuing this treatment option.
Success Rates
Research shows that steroid injections can be successful in shrinking lipomas in dogs, but may not eliminate the need for surgery in all cases. One study found that steroid injections resulted in over 50% shrinkage in 71% of lipomas treated and over 75% shrinkage in 46% of lipomas (Lamagna et al., 2012). However, 28% of treated lipomas later regrew between 9 months to 3 years later.
Another study found that non-infiltrative lipomas showed an average decrease of 62% in size after steroid injection, while infiltrative lipomas only decreased by 18% (Schultz & Adams, 2012). Complete lipoma resolution only occurred in 23% of cases. The researchers concluded that steroid injections can reduce surgical size and invasiveness, but do not eliminate the need for surgery in most cases.
Overall, research indicates steroid injections often reduce lipoma size substantially, but regrowth and incomplete resolution are common, meaning surgical removal may still be required, especially for infiltrative lipomas.
Lifestyle Changes
Making some lifestyle adjustments can be beneficial for preventing and managing lipomas in dogs. Since obesity is a risk factor, maintaining a lean body weight is very important. Keeping your dog at a healthy weight reduces fat deposits overall, which are what lipomas are made of. Discuss an appropriate calorie intake and exercise plan with your vet.
Supplementing your dog’s diet with omega-3 fatty acids can also help. Omega-3s have anti-inflammatory properties that may inhibit the growth of lipomas. Fish oil, krill oil, or other supplements are good sources. Always consult your vet before giving supplements.
Avoiding trauma to the lipoma area can help prevent irritation or rapid growth. Use a harness instead of a collar, install ramps to prevent jumping on/off furniture, and use bumpers or padding around sharp corners. Keep the area protected but don’t completely restrict your dog’s normal activity.
Monitoring Lipomas
It’s important for dog owners to regularly monitor any lipomas their dog has developed. This involves checking the size and texture of the lipoma regularly to look for any concerning changes that may indicate surgical removal is needed. According to VCA Animal Hospitals, lipomas that rapidly increase in size, interfere with mobility, or ulcerate should be surgically removed.
When monitoring a lipoma, look for key changes like:
- Sudden increase in size
- Change in texture – becoming firm, rough, or ulcerated
- Interference with movement or mobility
- Bleeding, redness, or discharge
Any of these changes indicate it’s time to take your dog to the vet. The vet can evaluate if surgical removal is necessary at that point. Otherwise, routine monitoring every few weeks helps keep track of the lipoma’s progression. It’s ideal to establish a baseline size and texture when the lipoma is first diagnosed, for comparison over time.
When to See a Vet
In most cases, lipomas in dogs are benign and do not require any treatment. However, there are certain situations when veterinary attention is recommended:1
You should schedule an appointment with your vet if the lipoma is growing rapidly or has changed texture. Lipomas that enlarge quickly may indicate a more serious health issue. Contact your vet if the lipoma becomes painful for your dog or interferes with movement, walking, or other functions.
Also watch for any ulceration, bleeding, or discharge coming from the lipoma. This could be a sign of infection or that the tissue has become necrotic. Any time a lipoma ruptures, leaks fluid, or bleeds you should have your vet examine it right away.2
Lipomas located in certain areas like the armpits, groin, or near joints have a higher risk of impeding mobility or causing discomfort. Consult with your veterinarian if a lipoma develops in sensitive body regions that could impact your dog’s normal activities.
Summary/Conclusions
In summary, steroid injections may reduce the size of lipomas in some cases, but success rates can vary. The lipomas often return after shrinking, requiring additional injections. Steroids carry risks of side effects, so they may not be the best long-term treatment option for all dogs.
When deciding how to treat lipomas, pet owners should consider factors like the dog’s age, health status, size and location of lipomas, cost of treatment, and potential side effects. More research is still needed to determine the overall effectiveness of steroid injections on canine lipomas.
If lipomas are small and not affecting mobility or quality of life, monitoring their growth and opting against treatment may be reasonable. But larger or problematic lipomas may require steroid injections or surgical removal. Consulting with a veterinarian is advisable to determine the best treatment approach for each individual dog.
