What are fatty tumors in dogs?
Fatty tumors, also known as lipomas, are benign masses or growths that develop under a dog’s skin (source). Lipomas consist of fat cells that clump together in a capsule. They can develop anywhere on a dog’s body where fat cells are present.
Lipomas most commonly occur on a dog’s torso, upper legs, upper back, and shoulders. They feel soft and movable under the skin. Lipomas are usually small, ranging from 1-2 inches in diameter, though they can grow much larger. Their appearance varies from oval or round shaped lumps that sit right underneath the skin, to growths with a more irregular shape (source).
While the fatty tumors are often benign, in rare cases they can be a sign of a fatty tumor cancer called liposarcoma. However, the vast majority of lipomas in dogs are noncancerous.
What causes fatty tumors in dogs?
The exact cause of fatty tumors in dogs is unknown, but there are some potential risk factors that may increase a dog’s chance of developing them:
Obesity – Overweight and obese dogs seem to be more prone to developing fatty tumors. The excess fat cells in obese dogs may multiply abnormally and form lumps under the skin.
Genetics – Certain breeds like Labrador Retrievers, Doberman Pinschers, and Miniature Schnauzers tend to get fatty tumors more often, suggesting there may be a genetic component.
Age – Older dogs are more likely to develop fatty tumors, with most occurring in dogs over 5 years old. The tumors tend to grow slowly over time.
Nutrition – Some studies show dogs fed high calorie diets with lots of animal fat may be more prone to fatty tumor development. Carbohydrates and chemical preservatives in low quality dog foods could also be a factor.
While the exact triggers are unknown, keeping your dog fit and feeding a high quality diet may help reduce risk. Talk to your vet if you notice any unusual lumps on your dog to determine if fatty tumors are present.
How common are fatty tumors in dogs?
Fatty tumors are very common in dogs, especially as they get older. According to research, lipomas have been confirmed as a common clinical diagnosis with a one-year prevalence of 1.94% in dogs under primary veterinary care in the UK. Another study found that up to 50% of dogs can develop fatty tumors at some point in their lives.
Certain breeds seem to be more prone to developing fatty tumors. Overweight and middle-aged to older dogs are also at an increased risk. So fatty tumors are an extremely common occurrence in the canine population.
Can fatty tumors in dogs disappear on their own?
Fatty tumors (lipomas) rarely resolve on their own without any treatment according to veterinarians. Lipomas form from fat cells that multiply rapidly and lump together in cysts or masses under the skin. Since they are made up of fat cells, lipomas do not disappear unless the fat content is reduced.
In some cases, lipomas may reduce in size if a dog loses a significant amount of weight. A calorie-restricted diet and exercise regimen designed by a veterinarian can help obese dogs lose weight and shrink the size of fatty tumors. However, even with major weight loss, most lipomas will not fully disappear on their own.
Lipomas can also shrink temporarily if a steroid injection is administered directly into the tumor to reduce inflammation. However, studies show that in most cases lipomas return to their original size within 3-6 months after steroid treatment (https://www.dogsnaturallymagazine.com/6-herbs-to-get-rid-of-fatty-tumors-in-dogs/).
While non-cancerous lipomas are usually harmless, it’s recommended to have all lumps and growths evaluated by a veterinarian to determine if they are fatty tumors or another type of mass. Leaving any abnormal growth unchecked can allow it to enlarge and potentially impair a dog’s mobility or quality of life.
Should fatty tumors in dogs be removed?
Fatty tumors in dogs, also known as lipomas, are often harmless growths that do not require surgical removal. According to the American Animal Hospital Association (https://www.animalsurgicalcenter.com/fatty-tumors–lipomas), the majority of lipomas do not need to be surgically removed unless they interfere with mobility or quality of life.
However, there are some instances where surgical removal of a fatty tumor may be recommended (https://www.amcny.org/blog/2022/07/13/my-dog-has-a-fatty-tumor-now-what/):
- The fatty tumor is in a location where it limits movement or causes discomfort
- The fatty tumor grows rapidly or changes appearance
- The fatty tumor interferes with bodily functions
- The fatty tumor becomes inflamed, infected, ulcerated or bleeding
- There is suspicion the fatty tumor may be cancerous
In these cases, surgical removal can help improve quality of life and mobility. It’s best to monitor the size and appearance of fatty tumors, reporting any changes to your veterinarian.
What happens if fatty tumors in dogs are left untreated?
Fatty tumors (lipomas) in dogs are usually benign (non-cancerous) and generally harmless. However, if left untreated, large fatty tumors can cause problems by interfering with the movement of muscles, joints, and limbs. Some potential issues that may occur if large fatty tumors are left untreated include:
Impeded mobility – If a fatty tumor grows to a large size, it can impede a dog’s ability to move normally by restricting joint motion. This is especially true if the fatty tumor develops around or near a joint.
Muscle loss – Compression from an untreated large fatty tumor can lead to muscle loss and atrophy in surrounding tissue from lack of use.
Skin irritation – Friction from an untreated large fatty tumor rubbing on the skin can lead to irritation, hair loss, and open sores.
In rare cases, a fatty tumor could affect nerves or blood vessels if it grows large enough, which can lead to additional problems.
Many veterinarians recommend having lipomas removed once they reach around 2-3 inches in diameter or larger. This helps avoid mobility issues or secondary problems from developing as they continue growing over time. While not malignant, large untreated lipomas do have the potential to negatively impact comfort and quality of life.
How are fatty tumors in dogs diagnosed?
Fatty tumors in dogs are often initially discovered by pet owners who notice a lump or bump on their dog while petting or grooming. However, a veterinarian will need to perform a full physical exam and potentially some diagnostic tests to confirm that the mass is actually a benign fatty tumor.
During the physical exam, the veterinarian will look at the location, size, shape, texture and mobility of the mass. They will palpate the lump to see if it moves freely under the skin and feels soft. The vet will also look for any other lumps on the body. This clinical examination gives the vet an indication if the lump could be a benign lipoma.
If the vet suspects the lump may not be a simple fatty tumor, they may recommend a fine needle aspirate. This involves using a small needle to suction out some cells from the mass so they can be examined under a microscope. This cytology test helps rule out cancer or other tumors like a mast cell tumor. If the lump appears suspicious, a biopsy may be done to remove a small piece for further testing.[1]
In straightforward cases where the vet is confident in the diagnosis of a fatty tumor just from the physical exam, no additional testing is needed. But aspiration or biopsy allows for confirmation of the diagnosis if there is any uncertainty.
What are the treatment options for fatty tumors in dogs?
There are a few different treatment options for fatty tumors in dogs depending on the size, location, and whether they are benign or cancerous:
Observation: If the fatty tumor is small and not bothering the dog, a vet may recommend just monitoring it closely and leaving it alone. Lipomas often grow slowly and may never cause problems.[1]
Surgery: Surgical removal is usually recommended for lipomas that are large, growing quickly, limiting mobility, or irritating the dog.[2] The surgery is minimally invasive since the tumors are encapsulated and easy to remove. Recovery is often quick.
Liposuction: In some cases, liposuction may be done instead of surgical excision to remove the fatty tumor. This also minimally invasive.
Radiation or chemotherapy: If a fatty mass is found to be cancerous, options like radiation or chemotherapy may be considered. These help kill cancer cells and reduce tumor size.
The best course of treatment depends on each dog’s unique situation. Consulting a vet is important to determine if and how a fatty tumor should be removed or treated.
What is the prognosis for dogs with fatty tumors?
The prognosis for dogs with fatty tumors is generally excellent. Fatty tumors are typically benign growths that do not metastasize (spread) to other areas of the body. As long as the tumors do not interfere with normal body functions or become ulcerated, most doctors recommend leaving them alone and monitoring for any changes.
In most cases, dogs can live normal, full lives with fatty tumors present. Only a small percentage of fatty tumors undergo malignant transformation. Owners should monitor the location, size, shape, texture, and appearance of any masses and alert the veterinarian about any sudden changes. Routine examinations will allow the veterinarian to assess the tumors over time.
Surgically removing fatty tumors can improve the dog’s prognosis and prevent any problems if the mass was to continue growing larger. However, surgery may not be recommended for dogs with many tumors or for very large tumors attached to major blood vessels or organs. In these cases, monitoring the masses may still result in an excellent long-term prognosis as long as no cancerous changes occur.
With regular veterinary care and monitoring, most lipomas will not impact a dog’s overall wellbeing. Dogs can live happily alongside these fatty growths. Only significant changes to the tumor’s characteristics require rapid veterinary assessment and possible intervention.
How Can Fatty Tumors in Dogs Be Prevented?
Maintaining a healthy weight for your dog can help prevent fatty tumors. Overweight and obese dogs are more prone to developing lipomas according to this source. By keeping your dog at a healthy weight with the right diet and exercise, you reduce excess fat buildup under the skin that leads to lipoma formations.
Regular wellness checks with your veterinarian can also help monitor for any new fatty tumor growths. Your vet will be able to feel for any abnormal lumps or bumps under your dog’s skin during an exam. Catching lipomas early allows for quicker treatment before they can grow too large.
While fatty tumors often form due to genetics in certain breeds, maintaining your dog’s overall health is key. A healthy diet, regular exercise, and annual vet exams to screen for tumors are all recommended ways to help prevent lipomas in dogs.
